UBIQUINONE ANALOGS AND METHODS OF USE

Abstract

New ubiquinone and ubiquinol analogs are disclosed, as well as methods of making and using these compounds.

Description

BACKGROUND OF THE INVENTION

The ubiquinones, also commonly called coenzyme Q_n (n=1-12), constitute essential cellular components of many life forms. In humans, CoQ₁₀ is the predominant member of this class of polyprenoidal natural products and is well-known to function primarily as a redox carrier in the respiratory chain (Lenaz, COENZYME Q. BIOCHEMISTRY, BIOENERGETICS, AND CLINICAL APPLICATIONS OF UBIQUINONE, Wiley-Interscience: New York (1985); Trumpower, FUNCTION OF UBIQUINONES IN ENERGY CONSERVING SYSTEMS, Academic Press. New York (1982); Thomson, R. H., NATURALLY OCCURRING QUINONES, 3rd ed., Academic Press, New York (1987); Bliznakov et al., THE MIRACLE NUTRIENT COENZYME Q₁₀, Bantom Books, New York (1987)).

Coenzyme Q plays an essential role in the orchestration of electron-transfer processes necessary for respiration. Almost all vertebrates rely on one or more forms of this series of compounds that are found in the mitochondnra of every cell (i.e., they are ubiquitous, hence the alternative name “ubiquinones”). Although usually occurring with up to 12 prenoidal units attached to a p-quinone headgroup, CoQ₁₀ is the compound used by humans as a redox carrier. Oftentimes unappreciated is the fact that when less than normal levels are present, the body must construct its CoQ₁₀ from lower forms obtained through the diet, and that at some point in everyone's life span the efficiency of that machinery begins to drop. (Blizakov et al., supra) The consequences of this in vivo deterioration can be substantial; levels of CoQ₁₀ have been correlated with increased sensitivity to infection (i.e., a weakening of the immune system), strength of heart muscle, and metabolic rates tied to energy levels and vigor. In the United States, however, it is considered a dietary supplement, sold typically in health food stores or through mail order houses at reasonable prices. It is indeed fortunate that quantities of CoQ₁₀ are available via well-established fermentation and extraction processes (e.g., Sasikala et al., Adv. Appl. Microbiol., 41:173 (1995); U.S. Pat. Nos. 4,447,362; 3,313,831; and 3,313,826) an apparently more cost-efficient route relative to total synthesis. However, for producing lower forms of CoQ, such processes are either far less efficient or are unknown. Thus, the costs of these materials for research purposes are astonishingly high, e.g., COQ₆ is ˜$22,000/g, and CoQ₉ is over $40,000/g. (Sigma-Aldrich Catalog, Sigma-Aldrich: St. Louis, pp. 306-307 (1998)).

Given the biological activities of the naturally occurring ubiquinones, there is great interest in the art to provide synthetic ubiquinone analogs as well as analogs of the structurally related ubiquinols, which represent the reduced forms of the corresponding ubiquinones. Methods for the synthesis of ubiquinones and ubiquinols as well as their respective analogs are described in U.S. Pat. No. 6,545,184 to Lipshutz et al. and U.S. Patent Application No. 20050148675 to Lipshutz et al.

Availability of novel ubiquinones and their analogs with greater structural variety and pysico-chemical properties (e.g., reduction potential), which are different from those of naturally occurring ubiquinones, would contribute to the development of novel treatment options, e.g., for patients with mitochondrial diseases and/or conditions associated with ubiquinone/ubiquinol deficiencies. In addition, methods for the preparation of such novel ubiquinones are needed. The present invention addresses these and other needs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing reduction waves for compound 1 (●) (first and second reduction potential: −1.04 and −1.35 mV), compound 23 (▪) (reduction potential: −1.44 mV) and CoQ₁₀ (♦) (first and second reduction potential: −1.11 and −1.42 mV).

SUMMARY OF THE INVENTION

The present invention provides a series of novel ubiquinone and reduced ubiquinone (ubiquinol) analogs as well as methods for their preparation and methods of using the compounds.

In a first aspect, the present invention provides compounds according to Formula (I) and Formula (II):

In Formula (I) and Formula (II), the integer n is selected from 0 to 13. R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, wherein R² and R³, together with the carbon atoms to which they are attached, are optionally joined to form a 5- to 7-membered ring. When R¹, R² and R³ are each independently selected from H and unsubstituted C₁-C₂ alkyl, n is preferably greater than 3, more preferably greater than 5. Most preferably, n is 9. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both, substituted or unsubstituted alkoxy, and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are preferably not joined to form an unsubstituted phenyl ring.

In Formula (II), R¹⁰ and R¹¹ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl. In a preferred embodiment, R¹⁰ and R¹¹ do not include a hydrophilic polymeric moiety selected from a polyether and a polyalcohol. In another preferred embodiment, R¹⁰ and R¹¹ do not include a labeling moiety, a targeting moiety or a drug moiety.

In a second aspect, the invention provides a compound according to Formula (III):

In Formula (III), R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted alkyl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, wherein R² and R³, together with the carbon atoms which they are attached, are optionally joined to form a 5- to 7-membered ring. When R¹ is a member selected from H and unsubstituted C₁-C₂ alkyl, R² and R³ are preferably not both unsubstituted C₁-C₂ alkyl. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both substituted or unsubstituted alkoxy; and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are preferably not joined to form an unsubstituted phenyl ring.

In Formula (III), Z is a member selected from R⁶, OR⁶, SR⁶, NR⁶R⁷ and a leaving group, wherein R⁶ and R⁷ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl.

In a third aspect, the invention provides a compound according to Formula (VII):

In Formula (VII), R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, wherein R² and R³, together with the carbon atoms to which they are attached, are optionally joined to form a 5- to 7-membered ring. When R¹ is a member selected from H and unsubstituted C₁-C₂ alkyl, R² and R³ are preferably not both unsubstituted C₁-C₂ alkyl. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both substituted or unsubstituted alkoxy; and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are not joined to form an unsubstituted phenyl ring.

In Formula (VII), R⁴ is a member selected from H and a protecting group. R⁵ is a member selected from branched, unsaturated alkyl, —C(O)H, and CH₂Y in which Y is OR⁸, SR⁸, NR⁸R⁹, and a leaving group, wherein R⁸ and R⁹ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl.

In another aspect, the present invention provides methods for the synthesis of the compounds of the invention, as well as pharmaceutical formulations comprising a compound of the invention and a pharmaceutically acceptable carrier.

In a further aspect, the present invention provides a method for treating a condition, which is a member selected from a neurological disorder (e.g., a central nervous system disorder), a mitochondrial disease and a heart disease. The method includes administering to a subject in need thereof a therapeutically effective amount of a compound of the invention or a pharmaceutically acceptable salt or solvate thereof.

Other objects and advantages of the invention will be apparent to those of skill in the art from the detailed description that follows.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS

I. Definitions

The term “alkyl,” by itself or as part of another substituent, means, unless otherwise stated, a straight or branched chain, or cyclic hydrocarbon radical, or combination thereof, which may be fully saturated, mono- or polyunsaturated and can include di- and multivalent radicals, having the number of carbon atoms designated (i.e. C₁-C₁₀ means one to ten carbons). Examples of saturated hydrocarbon radicals include, but are not limited to, groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. An unsaturated alkyl group is one having one or more double bonds or triple bonds. Examples of unsaturated alkyl groups include, but are not limited to, vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl, 3-butynyl, and the higher homologs and isomers. The term “alkyl,” unless otherwise noted, is also meant to include those derivatives of alkyl defined in more detail below, such as “heteroalkyl.” Alkyl groups that are limited to hydrocarbon groups are termed “homoalkyl”.

The term “alkylene” by itself or as part of another substituent means a divalent radical derived from an alkane, as exemplified, but not limited, by —CH₂CH₂CH₂CH₂—, and further includes those groups described below as “heteroalkylene.” Typically, an alkyl (or alkylene) group will have from 1 to 24 carbon atoms, with those groups having 10 or fewer carbon atoms being preferred in the present invention. A “lower alkyl” or “lower alkylene” is a shorter chain alkyl or alkylene group, generally having eight or fewer carbon atoms.

The terms “alkoxy,” “alkylamino” and “alkylthio” (or thioalkoxy) are used in their conventional sense, and refer to those alkyl groups attached to the remainder of the molecule via an oxygen atom, an amino group, or a sulfur atom, respectively.

The term “heteroalkyl,” by itself or in combination with another term, means, unless otherwise stated, a stable straight or branched chain, or cyclic hydrocarbon radical, or combinations thereof, consisting of the stated number of carbon atoms and at least one heteroatom selected from the group consisting of O, N, Si and S, and wherein the nitrogen and sulfur atoms may optionally be oxidized and the nitrogen heteroatom may optionally be quaternized. The heteroatom(s) O, N and S and Si may be placed at any interior position of the heteroalkyl group or at the position at which the alkyl group is attached to the remainder of the molecule. Examples include, but are not limited to, —CH₂—CH₂—O—CH₃, —CH₂—CH₂—NH—CH₃, —CH₂—CH₂—N(CH₃)—CH₃, —CH₂—S—CH₂—CH₃, —CH₂—CH₂, —S(O)—CH₃, —CH₂—CH₂—S(O)₂—CH₃, —CH═CH—O—CH₃, —Si(CH₃)₃, —CH₂—CH═N—OCH₃, and —CH═CH—N(CH₃)—CH₃. Up to two heteroatoms may be consecutive, such as, for example, —CH₂—NH—OCH₃ and —CH₂—O—Si(CH₃)₃. Similarly, the term “heteroalkylene” by itself or as part of another substituent means a divalent radical derived from heteroalkyl, as exemplified, but not limited by, —CH₂—CH₂—S—CH₂—CH₂— and —CH₂—S—CH₂—CH₂—NH—CH₂—. For heteroalkylene groups, heteroatoms can also occupy either or both of the chain termini (e.g., alkyleneoxy, alkylenedioxy, alkyleneamino, alkylenediamino, and the like). Still further, for alkylene and heteroalkylene linking groups, no orientation of the linking group is implied by the direction in which the formula of the linking group is written. For example, the formula —CO₂R′— represents both —C(O)OR′ and —OC(O)R′.

The terms “cycloalkyl” and “heterocycloalkyl”, by themselves or in combination with other terms, represent, unless otherwise stated, cyclic versions of “alkyl” and “heteroalkyl”, respectively. Additionally, for heterocycloalkyl, a heteroatom can occupy the position at which the heterocycle is attached to the remainder of the molecule. Examples of cycloalkyl include, but are not limited to, cyclopentyl, cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, cycloheptyl, and the like. Examples of heterocycloalkyl include, but are not limited to, 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4-morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl, 1 piperazinyl, 2-piperazinyl, and the like.

The terms “halo” or “halogen,” by themselves or as part of another substituent, mean, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom. Additionally, terms such as “fluoroalkyl,” are meant to include monofluoroalkyl and polyfluoroalkyl.

The term “aryl,” employed alone or in combination with other terms (e.g., aryloxy, arylthioxy, arylalkyl) means, unless otherwise stated, an aromatic substituent which can be a single ring or multiple rings (up to three rings), which are timed together or linked covalently. “Heteroaryl” are those aryl groups having at least one heteroatom ring member. Typically, the rings each contain from zero to four heteroatoms selected from N, O, and S, wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen atom(s) are optionally quaternized. The “heteroaryl” groups can be attached to the remainder of the molecule through a heteroatom. Non-limiting examples of aryl and heteroaryl groups include phenyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl, 4-pyrimidyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl, 1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 3-quinolyl, and 6-quinolyl. Substituents for each of the above noted aryl ring systems are selected from the group of acceptable substituents described below. The term “arylalkyl” is meant to include those radicals in which an aryl group is attached to an alkyl group (e.g., benzyl, phenethyl, pyridylmethyl and the like) or a heteroalkyl group (e.g., phenoxymethyl, 2-pyridyloxymethyl, 3-(1-naphthyloxy)propyl, and the like).

Each of the above terms (e.g., “alkyl,” “heteroalkyl” and “aryl”) are meant to include both substituted and unsubstituted forms of the indicated radical. Preferred substituents for each type of radical are provided below.

Substituents for the alkyl and heteroalkyl radicals (including those groups often referred to as alkylene, alkenyl, heteroalkylene, heteroalkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, and heterocycloalkenyl) are generically referred to as “alkyl group substituents.” and they can be one or more of a variety of groups selected from, but not limited to: substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl, —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′, -halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, —CONR′R″, —OC(O)NR′R″, —NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′, —NR—C(NR′R″R′″)═NR″″, —NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″, —NRSO₂R′, —CN and —NO₂ in a number ranging from zero to (2m′+1), where m′ is the total number of carbon atoms in such radical. R′, R″, R′″ and R″″ each preferably independently refer to hydrogen, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, e.g., aryl substituted with 1-3 halogens, substituted or unsubstituted alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups. When a compound of the invention includes more than one R group, for example, each of the R groups is independently selected as are each R′, R″, R′″ and R″″ groups when more than one of these groups is present. When R′ and R″ are attached to the same nitrogen atom, they can be combined with the nitrogen atom to form a 5-, 6-, or 7-membered ring. For example, —NR′R″ is meant to include, but not be limited to, 1-pyrrolidinyl and 4-morpholinyl. From the above discussion of substituents, one of skill in the art will understand that the term “alkyl” is meant to include groups including carbon atoms bound to groups other than hydrogen groups, such as haloalkyl (e.g., —CF₃ and —CH₂CF₃) and acyl (e.g., —C(O)CH₃, —C(O)CF₃, —C(O)CH₂OCH₃, and the like).

Similar to the substituents described for the alkyl radical, substituents for the aryl and heteroaryl groups are generically referred to as “aryl group substituents.” The substituents are selected from, for example: substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl, —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′, -halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, —CONR′R″, —OC(O)NR′R″, —NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′, —NR—C(NR′R″R′″)═NR″″, —NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″, —NRSO₂R′, —CN and —NO₂, —R′, —N₃, —CH(Ph)₂, fluoro(C₁-C₄)alkoxy, and fluoro(C₁-C₄)alkyl, in a number ranging from zero to the total number of open valences on the aromatic ring system; and where R′, R″, R′″ and R″″ are preferably independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. When a compound of the invention includes more than one R group, for example, each of the R groups is independently selected as are each R′, R″, R′″ and R″″ groups when more than one of these groups is present.

Two of the substituents on adjacent atoms of the aryl ring may optionally be replaced with a substituent of the formula -T-C(O)—(CH₂)_q—U—, wherein T and U are independently —NH—, —O—, —CH₂— or a single bond, and the subscript q is an integer of from 0 to 2. Alternatively, two of the substituents on adjacent atoms of the aryl ring may optionally be replaced with a substituent of the formula -A-(CH₂)_r—B—, wherein A and B are independently —CH₂—, —O—, —NH—, —S—, —S(O)—, —S(O)₂—, —S(O)₂NR′— or a single bond, and r is an integer of from 1 to 3. One of the single bonds of the new ring so formed may optionally be replaced with a double bond. Alternatively, two of the substituents on adjacent atoms of the aryl ring may optionally be replaced with a substituent of the formula —(CH₂), —X—(CH₂)_t—, where s and t are independently integers of from 0 to 3, and X is —O—, —NR′—, —S—, —S(O)—, —S(O)₂—, or —S(O)₂NR′—. The substituent R′ in —NR′ and —S(O)₂NR′— is selected from hydrogen or unsubstituted (C₁-C₆)alkyl.

Certain compounds of the present invention possess asymmetric carbon atoms (optical centers) or double bonds; the racemates, diastereomers, geometric isomers and individual isomers are all encompassed within the scope of the present invention.

The compounds of the present invention may also contain unnatural proportions of atomic isotopes at one or more of the atoms that constitute such compounds. For example, the compounds may be radiolabeled with radioactive isotopes, such as for example tritium (³H), iodine-125 (¹²⁵I) or carbon-14 (¹⁴C). All isotopic variations of the compounds of the present invention, whether radioactive or not, are intended to be encompassed within the scope of the present invention.

As used herein, the term “leaving group” refers to a portion of a substrate that is cleaved from the substrate in a reaction. The leaving group is an atom (or a group of atoms) that is displaced as stable species taking with it the bonding electrons. Typically the leaving group is an anion (e.g., Cl⁻) or a neutral molecule (e.g., H₂O). Exemplary leaving groups include a halogen, OC(O)R⁶⁵, OP(O)R⁶⁵R⁶⁶, OS(O)R⁶⁵, and OSO₂R⁶⁵. R⁶⁵ and R⁶⁶ are members independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl. Useful leaving groups include, but are not limited to, other halides, sulfonic esters, oxonium ions, alkyl perchlorates, sulfonates, e.g., arylsulfonates, ammonioalkanesulfonate esters, and alkylfluorosulfonates, phosphates, carboxylic acid esters, carbonates, ethers, and fluorinated compounds (e.g., triflates, nonaflates, tresylates), S R⁶⁵, (R⁶⁵)₃P⁺, (R⁶⁵)₂S⁺, P(O)N(R⁶⁵)₂(R⁶⁵)₂, p(O)XR⁶⁵X′R⁶⁵ in which each R⁶⁵ is independently selected from the members provided in this paragraph and X and X′ are S or O. The choice of these and other leaving groups appropriate for a particular set of reaction conditions is within the abilities of those of skill in the art (see, for example, March J, ADVANCED ORGANIC CHEMISTRY, 2nd Edition, John Wiley and Sons, 1992; Sandler S R, Karo W, ORGANIC FUNCTIONAL GROUP PREPARATIONS, 2nd Edition, Academic Press, Inc., 1983; and Wade L G, COMPENDIUM OF ORGANIC SYNTHETIC METHODS, John Wiley and Sons, 1980).

“Protecting group,” as used herein refers to a portion of a substrate that is substantially stable under a particular reaction condition, but which is cleaved from the substrate under a different reaction condition. A protecting group can also be selected such that it participates in the direct oxidation of the aromatic ring component of the compounds of the invention. For examples of useful protecting groups, see, for example, Greene et al., PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, 3rd ed., John Wiley & Sons, New York, 1999.

The term “labeling moiety” refers to a moiety, which provides a signal that is detectable by a detection method known in the art. The signal can be used to determine the location or concentration of the labeling moiety, for example, in an organism, a tissue sample or a reaction vial. Exemplary signals include color, emitted light of any wavelength, radioactivity, or any other electromagnetic or quantum mechanical effect. Exemplary labeling moieties include but are not limited to fluorescent molecules (e.g. fluorescein), luminescent moieties (e.g., transition-metal complexes), chemoluminescent molecules, molecules used in calorimetric applications (i.e. dye molecules), histochemical staining reagents, photoaffinity labels, magnetic resonance imaging (MRI) agents, radioactive labels, radiotracers and agents used in positron emission tomography (PET).

The term “targeting moiety” refers to a moiety which is capable of binding to a particular tissue- or cell-type (e.g., tumor cells, neuronal or glial cells, liver cells, and the like) with at least some level of specificity. Exemplary targeting moieties are selected from carbohydrates, proteins, peptides, antibodies, and small-molecule ligands. In an exemplary embodiment, the targeting moiety is a ligand for a biological receptor, such as a cell surface receptor. In another exemplary embodiment, the targeting moiety is an antibody that is capable of binding to an antigen, such as a tissue- or tumor-specific antigen.

The term “drug moiety” refers to pharmaceutical drugs and other biologically active molecules. “Drug moiety” includes small-molecule drugs as well as biologics, including peptides, mutant and wild-type polypeptides, mutant and wild-type proteins, antibodies (e.g., humanized, monoclonal antibodies) and the like.

“Ring” as used herein means a substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl. A ring includes fused ring moieties. The number of atoms in a ring is typically defined by the number of members in the ring. For example, a “5- to 7-membered ring” means there are 5 to 7 atoms in the encircling arrangement. The ring to optionally included a heteroatom. Thus, the term “5- to 7-membered ring” includes, for example pyridinyl and piperidinyl. The term “ring” further includes a ring system comprising more than one “ring”, wherein each “ring” is independently defined as above.

“Adsorbent”, as used herein refers to a material with the property to hold molecules of fluids without causing a chemical or physical change. Examples are Silica gel, Alumina, Charcoal, Ion exchange resins and others, characterized by high surface/volume ratio.

As used herein, the term “acyl” describes a substituent containing a carbonyl residue, C(O)R. Exemplary species for R include U, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and substituted or unsubstituted heterocycloalkyl.

As used herein, the term “fused ring system” means at least two rings, wherein each ring has at least 2 atoms in common with another ring. “Fused ring systems may include aromatic as well as non aromatic rings. Examples of “fused ring systems” are naphthalenes, indoles, quinolines, chromenes and the like.

As used herein, the term “heteroatom” includes oxygen (O), nitrogen (N), sulfur (S), silicon (Si) and boron (B).

The symbol “R” is a general abbreviation that represents a substituent group that is selected from substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and substituted or unsubstituted heterocycloalkyl groups.

The phrase “therapeutically effective amount” as used herein means that amount of a compound, or composition comprising a compound of the present invention which is effective for producing some desired therapeutic effect at a reasonable benefit/risk ratio applicable to any medical treatment.

The phrase “pharmaceutically acceptable” is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The phrase “pharmaceutically acceptable carrier” as used herein means any pharmaceutically acceptable material, which may be liquid or solid. Exemplary carriers include vehicles, diluents, additives, liquid and solid fillers, excipients, solvents, solvent encapsulating materials. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically-acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) pH buffered solutions; (21) polyesters, polycarbonates and/or polyanhydrides; and (22) other non-toxic compatible substances employed in pharmaceutical formulations.

The term “pharmaceutically acceptable salts” includes salts of the active compounds which are prepared with relatively nontoxic acids or bases, depending on the particular substituents found on the compounds described herein. When compounds of the present invention contain relatively acidic functionalities, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired base, either neat or in a suitable inert solvent Examples of pharmaceutically acceptable base addition salts include sodium, potassium, calcium, ammonium, organic amino, or magnesium salt, or a similar salt. When compounds of the present invention contain relatively basic functionalities, acid addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired acid, either neat or in a suitable inert solvent. Examples of pharmaceutically acceptable acid addition salts include those derived from inorganic acids like hydrochloric, hydrobromic, nitric, carbonic, monohydrogencarbonic, phosphoric, monohydrogenphosphoric, dihydrogenphosphoric, sulfuric, monohydrogensulfuric, hydriodic, or phosphorous acids and the like, as well as the salts derived from relatively nontoxic organic acids like acetic, propionic, isobutyric, maleic, malonic, benzoic, succinic, suberic, fumaric, lactic, mandelic, phthalic, benzenesulfonic, p-tolylsulfonic, citric, tartaric, methanesulfonic, and the like. Also included are salts of amino acids such as arginate and the like, and salts of organic acids like glucuronic or galactunoric acids and the like (see, for example, Berge et al., Journal of Pharmaceutical Science, 66: 1-19 (1977)). Certain specific compounds of the present invention contain both basic and acidic functionalities that allow the compounds to be converted into either base or acid addition salts.

As set out above, certain embodiments of the present compounds may contain a basic functional group, such as amino or alkylamino, and are, thus, capable of forming pharmaceutically acceptable salts with pharmaceutically acceptable acids. The term “pharmaceutically acceptable salts” in this respect, refers to the relatively non-toxic, inorganic and organic acid addition salts of compounds of the present invention. These salts can be prepared in situ in the administration vehicle or the dosage form manufacturing process, or by separately reacting a purified compound of the invention in its free base form with a suitable organic or inorganic acid, and isolating the salt thus formed during subsequent purification. Representative salts include the hydrobromide, hydrochloride, sulfate, sulfamate, bisulfate, phosphate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, tosylate, citrate, maleate, ascorbate, palmitate, fumarate, succinate, tartrate, napthylate, mesylate, hydroxymaleate, phenylacetate, glutamate, glucoheptonate, salicyclate, sulfanilate, 2-acetoxybenzoate, methanesulfonate, ethane disulfonate, oxalate, isothionate, lactobionate, and laurylsulphonate salts and the like. See, for example, Berge et al. (1977) “Pharmaceutical Salts”, J. Pharm. Sci. 66:1-19.

The neutral forms of the compounds are preferably regenerated by contacting the salt with a base or acid and isolating the parent compound in the conventional manner. The parent form of the compound differs from the various salt forms in certain physical properties, such as solubility in polar solvents, but otherwise the salts are equivalent to the parent form of the compound for the purposes of the present invention.

In addition to salt forms, the present invention provides compounds, which are in a prodrug form. Prodrugs of the compounds described herein are those compounds that readily undergo chemical changes under physiological conditions to provide the compounds of the present invention. Additionally, prodrugs can be converted to the compounds of the present invention by chemical or biochemical methods in an ex vivo environment. For example, prodrugs can be slowly converted to the compounds of the present invention when placed in a transdermal patch reservoir with a suitable enzyme or chemical reagent. An to exemplary prodrug of a compound according to Formula (II) includes at least one ester group and can be prepared by estenrfication of one or both of the phenolic hydroxy groups of a compound according to Formula (II), in which at least one of R¹⁰ and R¹¹ is H.

Certain compounds of the present invention can exist in unsolvated forms as well as solvated forms, including hydrated forms. In general, the solvated forms are equivalent to unsolvated forms and are encompassed within the scope of the present invention. Certain compounds of the present invention may exist in multiple crystalline or amorphous forms. In general, all physical forms are equivalent for the uses contemplated by the present invention and are intended to be within the scope of the present invention. “Compound or a pharmaceutically acceptable salt or solvate of a compound” intends the inclusive meaning of “or”, in that a material that is both a salt and a solvate is encompassed.

Certain compounds of the present invention possess asymmetric carbon atoms (optical centers) or double bonds; the racemates, diastereomers, geometric isomers and individual isomers are encompassed within the scope of the present invention. Optically active (R)- and (S)-isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques. When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless specified otherwise, it is intended that the compounds include both E and Z geometric isomers. Likewise, all tautomeric forms are also intended to be included.

The graphic representations of racemic, ambiscalemic and scalemic or enantiomerically pure compounds used herein are taken from Maehr, J. Chem. Ed., 62: 114-120 (1985): solid and broken wedges are used to denote the absolute configuration of a chiral element; wavy lines indicate disavowal of any stereochemical implication which the bond it represents could generate; solid and broken bold lines are geometric descriptors indicating the relative configuration shown but not implying any absolute stereochemistry; and wedge outlines and dotted or broken lines denote enantiomerically pure compounds of indeterminate absolute configuration.

The compounds of the present invention may also contain unnatural proportions of atomic isotopes at one or more of the atoms that constitute such compounds. For example, the compounds may be radiolabeled with radioactive isotopes, such as for example tritium (³H), iodine-125 (¹²⁵I) or carbon-14 (¹⁴C). All isotopic variations of the compounds of the present invention, whether radioactive or not, are intended to be encompassed within the scope of the present invention.

The term “neurological disorder” includes disorders that affect the central nervous system, the peripheral nervous system and the autonomic nervous system.

The term “central nervous system disorder” refers to any abnormal condition of the central nervous system of a mammal. Central nervous system disorder includes neurodegenerative diseases such Alzheimer's disease and Parkinson's disease, neuropsychiatric diseases (e.g. schizophrenia), anxieties, sleep disorders, depression, dementias, movement disorders, psychoses, alcoholism, post-traumatic stress disorder and the like. “Central nervous system disorder” also includes any condition associated with the disorder, such as loss of memory and/or loss of cognition. For instance, a method of treating a neurodegenerative disease would also include treating or preventing loss of neuronal function characteristic of such disease.

The term “mitochondrial disorder” as used herein means any disorder or condition that affects the function of the mitochondria and/or is due to mitochondrial DNA. For example, a “mitochondrial disorder” may be associated with a reduction in mitochondrial activity, e.g., with respect to production of energy in the form of ATP. Hence, many age-related diseases, which are associated with a reduction of cellular energy production, are “mitochondrial disorders” in the context of this application. “Mitochondrial disorder” includes any disorder or condition, commonly associated with “mitochondrial disorder”, alone or in combination with other conditions. Exemplary “mitochondrial disorders” include progressive external opthalmoplegia, diabetis mellitus, deafness, Leber hereditary optic neuropathy, mitochondrial encephalomyopathy, lactic acidosis, stroke-like syndrome, myoclonic epilepsy, ragged-red fibers, Leigh syndrome, subacute sclerosing encephalopathy, neuropathy, ataxia, retinitis pigmentosa, ptosis, Kearns-Sayre syndrome and myoneurogenic gastrointestinal encephalopathy. Additional conditions and diseases, which may be treated using the compounds of the invention, are described in Bliznakov, E. G., Hunt, G. L. The Miracle Nutrient Coenzyme Q10; Elsevier/North-Holland Biomedical Press: New York, 1986 and in Sinatra, S. T. The Coenzyme Q10 Phenomenon; Keats Publishing, Inc.: New Canaan, 1998, as well as Coenzyme Q: biochemistry, bioenergetics, and clinical applications of ubiquinone; Lenaz, G., Ed.; Wiley: New York, 1985 and Coenzyme Q: molecular mechanisms in health and disease; Kagan, V. E., Quinn, P. J., Eds.; CRC Press: Boca Raton, 2001. “Mitochondrial disorder” also includes the subclass of the disease characterized by neuromuscular disease symptoms, which are often referred to as mitochondrial myopathy. “Mitochondrial disorders” also includes any condition associated with the disorder, such as poor energy, poor physical strength and overall poor health.

II. Introduction

The present invention provides novel ubiquinone and ubiquinol (reduced ubiquinone) analogs and methods for the preparation of these molecules. The series of novel ubiquinone analogs are characterized by a variety of different reduction potentials. The invention further provides pharmaceutical compositions as well as methods of using the compounds of the invention.

III. Compositions

III. a.) Ubiquinone and Ubiquinol Analogs of Formula (I) and Formula (II)

In a first aspect, the present invention provides compounds according to Formula (I) and Formula (II).

In Formula (I) and Formula (II), the integer n is selected from 0 to 13. In a preferred embodiment, n is selected from 4 to 11 and more preferably, n is selected from 5 to 9. In a particularly preferred embodiment, n is 9. R¹, R² and R³ are members independently selected from aryl group substituents. In an exemplary embodiment, R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, wherein R² and R³, together with the carbon atoms to which they are attached, are optionally joined to form a 5- to 7-membered ring, which in turn can be part of a fused ring system.

When R¹, R² and R³ are each independently selected from H and unsubstituted C₁-C₂ alkyl, n is preferably greater than 3. Preferably greater than 3 includes those embodiments, in which n is preferably at least 4, at least 5, at least 6, at least 7, at least 8 and at least 9. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both substituted or unsubstituted alkoxy, and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are preferably not joined to form an unsubstituted phenyl ring.

In Formula (II), R¹⁰ and R¹¹ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl. In a preferred embodiment, R¹⁰ and R¹¹ do not include a hydrophilic polymeric moiety selected from a polyether and a polyalcohol. Exemplary polyethers are polyalkylene glycols, which include polymers of lower alkylene oxides, in particular polymers of ethylene oxide (polyethylene glycols) and propylene oxide (polypropylene glycols). In another preferred embodiment, R¹⁰ and R¹¹ do not include a labeling moiety, a targeting moiety or a drug moiety.

In an exemplary embodiment, R¹ is a member selected from H and methyl. In another exemplary embodiment R² and R³ are members independently selected from H, unsubstituted alkyl, unsubstituted alkoxy, halogen substituted alkyl, and halogen substituted alkoxy. In one embodiment of the invention R¹ is hydrogen and R² and R³ are members independently selected from H, unsubstituted alkyl, unsubstituted alkoxy, halogen substituted alkyl, and halogen substituted alkoxy.

Exemplary compounds according to this embodiment of the invention include:

In another embodiment of the invention R¹ is a methyl group and R² and R³ are members independently selected from H, unsubstituted alkyl and unsubstituted alkoxy.

Exemplary compounds according to this embodiment include: Wherein Z¹ is an aryl group substituent. In an exemplary embodiment, Z^t is a member selected from H, halogen, CN, substituted or unsubstituted alkoxy and substituted or unsubstituted alkyl.

In another embodiment, one or more of the substituents R¹, R² and R³ include halogen atoms to form, e.g., halogen substituted alkyl, and halogen substituted alkoxy groups. In one example, the halogen is fluoro. Exemplary fluoroalkyl and fluoroalkoxy groups according to this embodiment of the invention include but are not limited to CF₃, OCF₃, CHF₂, OCHF₂, CH₂F, and OCH₂F.

Exemplary compounds according to this embodiment of the invention include:

In another embodiment, R² and R³, together with the atomes to which they are attached, form a non-aromatic ring, which is optionally substituted. In one example, the non-aromatic ring includes heteroatoms, such as oxygen (e.g., tetrahydrofuran, tetrahydrothiophene, pyrrolidine, piperidine, 1,3-dioxolane, tetrahydro-2H-pyran, 1,4-dioxane and the like). In an exemplary embodiment, the ubiquinone and ubiquinol analogs have structures according to the following formulae: wherein X⁴, X⁵, X⁶ and X⁷ are members independently selected from H and halogen. In an exemplary embodiment the halogen is F.

In one embodiment, the compound according to Formula (II) has a structure according to Formula (XI):

In Formula (XI), R¹, R², R³ and the integer n are as defined above for Formula (II).

Y1 and Y2 are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, with the proviso that Y1 and Y2 do not include a labeling moiety, a targeting moiety or a drug moiety and with the farther proviso that Y1 and Y2 do not both consist of a hydrophilic polymeric moiety selected from a polyether and a polyalcohol.

Z1, Z2, Z3 and Z4 are members independently selected from 0 and 1. When Z4 and Z2 are both 0, (L2)_Z4-(Y2)_Z2 is preferably a member selected from H, a negative charge and a salt counterion; and when Z3 and Z1 are both 0, (L1)_Z3-(Y1)_Z1 is preferably a member selected from H, a negative charge and a salt counterion. L1 and L2 are independently selected linker moieties. Exemplary compounds according to this embodiment include one of the following moieties: wherein Y3 is a member selected from Y1 and Y2. Y4 and Y5 are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl with the proviso that Y4 and Y4 do not include a labeling moiety, a targeting moiety or a drug moiety and with the further proviso that Y4 and Y5 do not both consist of a hydrophilic polymeric moiety selected from a polyether and a polyalcohol.

In one embodiment, the compound of the invention has a reduction potential, which is different from the reduction potential of CoQ₁₀. In an exemplary embodiment, the reduction potential found for the compound of the invention is lower than the reduction potential of CoQ₁₀. Methods for the determination of reduction potentials are known in the art and are, for example, described in A. J. Fry, Synthetic Organic Electrochemistry, 2^nd Ed., Wiley-Interscience, New York, 1989. For example the reduction potential is measured against the Ag/AgNO₃ redox system. “Reduction potential” can mean “first reduction potential”, in which a first electron is transferred (e.g., Q→Q), or “second reduction potential”, in which a second electron is transferred (e.g., Q→Q⁻²). Typically, “reduction potential” for the purpose of comparing compounds, means the first reduction potential. However, for certain compounds a distinction between a first and a second reduction potential cannot be measured. In these cases, the “overall” (measurable) reduction potential is used to compare reduction potential values of compounds. The reduction potentials for selected ubiquinone analogs of the invention are summarized in Example 12, below. An exemplary reduction wave is shown in FIG. 1. For example, while the first reduction potential of CoQ₁₀ in a particular assay is −1.11, the first reduction potential found for compound 9 is −1.22, which is lower than −1.11. In another example, the overall reduction potential for compound 7 is −1.44, which is lower than −1.11 for CoQ₁₀. In an exemplary embodiment, the ratio (a/b) between the reduction potential of a compound of the invention (a) and the reduction potential of CoQ₁₀ to (b) in a particular assay is between about 1 and about 50. In another exemplary embodiment, the ratio is between about 1 and about 40, preferably between about 1 and about 30, more preferably between about 1 and about 20, and even more preferably between about 1 and about 10. In yet another exemplary embodiment, the ratio is between about 1 and about 8 preferably between about 1 and about 6, more preferably between about 1 and about 4, and most preferably between about 1 and about 2.

III. b.) Starting Materials

In a second aspect, the invention provides compounds according to Formula (III):

In Formula (III), R¹, R² and R³ are members independently selected from an alkylgroup substituent. In an exemplary embodiment, R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl. R² and R³, together with the carbon atoms which they are attached, are optionally joined to form a 5- to 7-membered ring, which in turn can be part of a fused ring system.

When R¹ is a member selected from H and unsubstituted C₁-C₂ alkyl, R² and R³ are preferably not both unsubstituted C₁-C₂ alkyl. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both substituted or unsubstituted alkoxy; and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are preferably not joined to form an unsubstituted phenyl ring.

In Formula (III), Z is a member selected from R⁶, OR⁶, SR⁶, NR⁶R⁷ and a leaving group, wherein R⁶ and R⁷ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl.

In an exemplary embodiment, Z is a halogen. Currently preferred compounds of Formula (III) include those wherein Z is Cl.

Exemplary compounds according to this embodiment of the invention include:

In a third aspect, the invention provides a compound according to Formula (VII):

In Formula (VII), R¹, R² and R³ are members independently selected from aryl group substituents. In an exemplary embodiment, R¹, R² and R³ are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl. R² and R³, together with the carbon atoms to which they are attached, are optionally joined to form a 5- to 7-membered ring.

When R¹ is a member selected from H and unsubstituted C₁-C₂ alkyl, R² and R³ are preferably not both unsubstituted C₁-C₂ alkyl. When R¹ is a member selected from H and substituted or unsubstituted alkyl, R² and R³ are preferably not both substituted or unsubstituted alkoxy; and when R¹ is a member selected from H and C₁-C₂ unsubstituted alkyl, R² and R³ are not joined to form an unsubstituted phenyl ring.

In Formula (VII), R⁴ is a member selected from H and a protecting group. R⁵ is a member selected from branched, unsaturated alkyl, —C(O)H, and CH₂Y in which Y is OR⁸, SR⁸, NR⁸R⁹, and a leaving group, wherein R⁸ and R⁹ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl.

In an exemplary embodiment Y is a halogen. In a preferred embodiment Y is Cl.

R⁴ can be any art-recognized protecting group. Useful phenol protecting groups include, but are not limited to ethers formed between the phenol oxygen atom and substituted or unsubstituted alkyl groups. Examples include: methoxy, ethoxy, sulfonic acid esters, methoxymethyl, benzyloxymethyl, methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl, methylthiomethyl, phenylthiomethyl, 2,2-dichloro-1,1-difluoroethyl, tetrahydropyranyl, phenacyl, p-bromophenacyl, cyclopropylmethyl, allyl, isopropyl, cyclohexyl, t-butyl, benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl, o-nitrobenzyl, 2,6-dichlorobenzyl, 4-(dimethylaminocarbonyl)benzyl, 9-anthrymethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl); silyl ethers (e.g., trimethylsilyl, t-butyldimethylsilyl); esters (e.g., acetate, levulinate, pivaloate, benzoate, 9-fluorenecarboxylate); carbonates (e.g., methyl, 2,2,2-trichloroethyl, vinyl, benzyl); phosphinates (e.g., dimethylphosphinyl, dimethylthiophosphinyl); sulfonates (e.g., methanesulfonate, toluenesulfonate, 2-formylbenzenesulfonate), and the like (see, e.g., Greene et al., PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, 3rd ed., John Wiley & Sons, New York, 1999).

In an exemplary embodiment, R⁵ includes a structure according to Formula (VI): wherein n is an integer selected from 0 to 13. In an exemplary embodiment, n is selected from 4 to 11, preferably from 5 to 9. In a particularly preferred embodiment n in Formula (VI) is 9. IV. Synthesis of the Compounds

Techniques useful in synthesizing the compounds of the invention are both readily apparent and accessible to those of skill in the relevant art. The discussion below is offered to illustrate certain of the diverse methods available for use in assembling the compounds of the invention and is not intended to define the scope of reactions or reaction sequences that are useful in preparing the compounds of the present invention. The reagents shown in Schemes III to XI, below, are exemplary and can be replaced with other art recognized reagents.

IV. a.) Synthesis of Compounds According to Formula (III) and Formula (VII)

The ubiquinone precursors according to Formula (III) and the aromatic analogs according to Formula (VII) are prepared by art-recognized methods or modifications thereof. For example, the synthesis of quinones functionalized with a halomethyl group can be accomplished using methods such as those described by Lipshutz et al. (e.g. Tetrahedron 1998, 54:1241-1253 and J. Am. Chem. Soc. 1999, 121: 11664-11673), the disclosures of which are incorporated herein by reference. In addition, the synthesis of substituted methylene aromatic moieties, such as phenols, can be accomplished using methods described by U.S. Pat. No. 6,545,184 to Lipshutz et al., and U.S. Patent Application No. 20050148675 to Lipshutz et al.; the disclosures of which are also herein incorporated by reference.

IV a.) i) Synthesis of the Compounds According to Formula (III)

In an exemplary embodiment compounds of Formula (III) are synthesized by performing one of the transformations outlined in Scheme I:

In Scheme I, the substituents X and Z are independently selected from a leaving group, R⁶, OR⁶, SR⁶ and NR⁶R⁷, wherein R⁶ and R⁷ are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl. R²¹ and R²² are members independently selected from H and lower alkyl. R¹, R² and R³ are as defined above.

In an exemplary embodiment, R¹, R² and R³ are independently selected from H, C1-C6 methyl and C1-C6 methoxy.

The method includes oxidation of either a phenolic compound 44 or a dialkoxy analog 45 to their corresponding quinones. The method may further include the replacement of the substituent X with the substituent Z, either before or after the oxidative step. In an exemplary embodiment X is OH and Z is Cl. In another exemplary embodiment, both X and Z are Cl.

The phenolic intermediate, such as compound 44 can be oxidized directly to the quinone or, alternatively, it can first be converted to the corresponding hydroquinone and then be oxidized to the quinone. An array of reagents and reaction conditions are known that can be used for the oxidation of phenols to quinones, see, for example, Trost B M et al. COMPREHENSIVE ORGANIC SYNTHESIS: OXIDATION, Pergamon Press, 1992.

In an exemplary embodiment, the oxidant includes a transition metal chelate. The chelate is preferably present in the reaction mixture in an amount from about 0.1 mol % to about 10 mol %. In another exemplary embodiment, the transition metal chelate is used in conjunction with an organic base, such as an amine. Exemplary amines are the trialkyl amines, such as triethylamine. In another exemplary embodiment, the transition metal chelate is Co(salen). The chelate can be a heterogeneous or homogeneous oxidant. In an exemplary embodiment, the chelate is a supported reagent. In another exemplary embodiment the oxidizing reagent is ceric ammonium nitrate [Ce(NH₄)₂(NO₃)₆].

The oxidative conversion of a substrate such as compound 44 or 45 to a compound according to Formula (III) is optionally performed under pressure that is greater than ambient pressure. Methods for conducting reactions under pressure are recognized in the art (see, e.g., Matsumoto and Acheson, ORGANIC SYNTHESIS AT HIGH PRESSURE, J. Wiley & Sons, NY, 1991).

In an exemplary embodiment a compound according to Formula (III) is synthesized following the procedure outlined in Scheme II. in which R² and R³ are as described above. In an exemplary embodiment according to this embodiment of the invention, R² and R³ are independently selected from substituted or unsubstituted alkyl.

In Scheme II, the dimethyl-protected hydroquinone 46 is converted to a chloromethyl analog 47, which is oxidized to the corresponding chloromethyl quinone (XI). The reagents given in Scheme II are exemplary. Other art recognized reagents can be used to accomplish the shown transformations. For instance, the oxidant ammonium cerium nitrate used in the last step can be replaced with other oxidants described above.

In another exemplary embodiment a compound according to Formula (III) is synthesized following the procedure outlined in Scheme III, below.

In Scheme III, the dimethoxymethylphenol 48 is formylated, yielding the aldehyde 49. After methylation of the phenolic hydroxy group, the aldehyde 50 is reduced to the benzylic alcohol 51, which is further converted to the chloromethyl analog 52. In the final step the chinone 33 is prepared by oxidation.

A wide array of art-recognized formylation methods can be used to introduce an aldehyde function such as that in compound 49. See, for example Jutz et al., Adv. Org. Chem. 1976, 9 (Part 1), 225-342.

A wide array of art-recognized reducing agents can be used for the reduction of an aldehyde, such as 50 to an alcohol, such as 51. See, for example, Trost et al., COMPREHENSIVE ORGANIC SYNTHESIS: REDUCTION, Pergamon Press, 1992. In an exemplary embodiment, the reducing agent is a reagent that is a source of hydrogen which is a member selected from the group consisting of metal hydrides. In another exemplary embodiment, the reduction is accomplished by catalytic hydrogenation. In yet another exemplary embodiment, the reduction is an electrochemical reduction.

The hydroxyl moiety of 51 is contacted with a halogenating agent, such as thionyl chloride, PCl₃ or another art recognized halogenation reagent affording the halide 52. Alternative halogenation reagents are given in MARCH'S ADVANCED ORGANIC CHEMISTRY, J. Wiley & Sons, NY, 2001).

The reaction pathways set forth in Scheme III can be altered by using a leaving group other than chloro at the methylene group of 52. Examples of useful leaving groups are provided herein. In an exemplary embodiment the hydroxyl moiety of 51 can be converted to an oxygen-containing moiety, such as a benzylic ether, which is prepared by contacting 51 with an alkylating agent. The resulting products can then either be coupled with a reagent according to Formula (IV) in the presence of a catalyst to afford an analog of a compound according to Formula (II), or can be oxidized to afford the corresponding quinone according to Formula (III).

Moreover, the methyl group used to protect the phenolic oxygen atom, for example, in compound 50 can be replaced with a number of art-recognized protecting groups. Useful phenol protecting groups include, but are not limited to, ethers formed between the phenol oxygen atom and substituted or unsubstituted alkyl groups (e.g., methoxy, ethoxy, sulfonic acid esters, methoxymethyl, benzyloxymethyl, methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl, methylthiomethyl phenylthiomethyl, 2,2-dichloro-1,1-difluoroethyl, tetrahydropyranyl, phenacyl, p-bromophenacyl, cyclopropylmethyl, allyl, isopropyl, cyclohexyl, t-butyl, benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl, o-nitrobenzyl, 2,6-dichlorobenzyl, 4-(dimethylaminocarbonyl)benzyl, 9-anthrymethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl); silyl ethers (e.g., trimethylsilyl, t-butyldimethylsilyl); esters (e.g., acetate, levulinate, pivaloate, benzoate, 9-fluorenecarboxylate); carbonates (e.g., methyl, 2,2,2-trichloroethyl, vinyl, benzyl); phosphinates (e.g., dimethylphosphinyl, dimethylthiophosphinyl); sulfonates (e.g., methanesulfonate, toluenesulfonate, 2-formylbenzenesulfonate), and the like (see, e.g., Greene et al., PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, 3rd ed., John Wiley & Sons, New York, 1999).

In another exemplary embodiment, compounds according to Formula (III) are prepared following the procedure outlined in Scheme IV: in which R², R³ and R⁴ are as described above. In an exemplary embodiment according to this aspect of the invention, R² and R³ are independently selected from substituted or unsubstituted alkyl, and substituted or unsubstituted alkoxy.

In Scheme IV the quinone 60 is prepared by oxidation of compound 59. The resulting quinone is converted to a compound according to Formula (III), in which Z is a halogen, by the action of formaldehyde in the presence of a selected halohydric acid. The synthetic route in Scheme IV may lead to an undesired side product 61. Methods for the purification of the product mixture can be found in U.S. Pat. No. 6,545,184 to Lipshutz et al., and U.S. Patent Application No. 20050148675 to Lipshutz et al.; the disclosures of which are also herein incorporated by reference.

IV. a.) ii.) Synthesis of the Compounds According to Formula (VII)

In an exemplary embodiment, a compound according to Formula (VII) is prepared by a method outlined in Scheme V: wherein R¹, R², R³ and R⁴ are as defined above.

The method of the invention includes formylating a compound such as 59 to produce an aldehyde such as 62. The aldehyde is contacted with a reducing agent thereby forming an alcohol such as compound 63. The alcohol or the corresponding alkoxide is contacted with a reagent that converts the —OH group into a leaving group, preferrably a halogen such as chloro in compound 64. Alternatively the intermediate formed after contacting compound 62 with the reducing agent is converted directly into the corresponding halide by contacting the intermediate with a protic halide source, such as hydrochloric acid. Formylation, reduction and halogenation methods are described above.

IV. b.) Synthesis of Ubiquinones and Ubiquinols

In one aspect, the method of the present invention is based on a retrosynthetic disconnection that relies on the well-known maintenance of olefin geometry in group 10 transition metal coupling reactions (Hegedus, TRANSITION METALS IN THE SYNTHESIS OF COMPLEX ORGANIC MOLECULES, University Science Books, Mill Valley, Calif. 1994). The discussion that follows focuses on a reaction, in which the coupling partners are a vinyl organometallic and a substituted-methylene quinone in which the methylene group is substituted with a leaving group (e.g., halomethyl quinone, ether, sulfonate, etc.). These reactions have similarities to coupling reactions between a vinyl alane and a protected, substituted-methylene phenol, as described in U.S. Pat. No. 6,545,184, the disclosure of which is herein incorporated by reference. The focus of the discussion is for clarity of illustration, and other methods and reagents appropriate for the preparation of the compounds of the invention (e.g., the described coupling reactions) will be apparent to those of skill in the art and are within the scope of the present invention.

The present invention provides methods for the preparation of compounds having structures according to Formula (I) and Formula (II):

In Formulae (I) and (II), each of R¹, R²R³ and n is as described above.

IV. b.) i.) Synthesis of the Ubiquinone Analogs According to Formula (I)

In one aspect the present invention provides a method of synthesizing the compound according to Formula (I), which includes, contacting a compound having a structure according to Formula (III): wherein each of R¹, R² and R³ is as described above and Z is a leaving group, and an organometallic species having a structure according to Formula (IV):

In Formula (IV), n is an integer from 0 to 13. L is an organometallic ligand, M is a metal and p is an integer selected from 1 to 5, wherein each of the p organometallic ligands is independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl.

The two components are contacted in the presence of a catalyst effective at catalyzing coupling between C* of the substituted methylene group according to Formula (III) and the organometallic species according to Formula (IV), thereby forming the compound according to Formula (I).

In an exemplary embodiment the leaving group Z in Formula (III) is a halogen. In another exemplary embodiment Z is chloro.

The preparation of organometallic species according to Formula (IV) can be accomplished using methods described in U.S. Pat. No. 6,545,184 to Lipshutz et al., and U.S. Patent Application No. 20050148675, the disclosures of which are herein incorporated by reference.

In an exemplary embodiment (L)_pM- is (L)₂Al—. In a particularly preferred embodiment, (L)_pM- is (CH₃)₂Al—.

In another aspect, the present invention provides a method of synthesizing the compound according to Formula (I), which includes, contacting a compound having a structure according to Formula (VIII): wherein R¹, R² and R³ are as defined above, Y is a leaving group and R⁴ is a protecting group, and an organometallic species having a structure according to Formula (IV): wherein n, L, M and p are as described above.

The two components are contacted in the presence of a catalyst effective at catalyzing coupling between the benzylic carbon atom C** according to Formula (VIII) and said organometallic species according to Formula (IV), thereby forming a compound according to Formula (IX):

The protecting group R⁴ is removed from the compound according to Formula (IX) to produce a compound according to Formula (X):

The resulting phenol is oxidized to the quinone of Formula (I) by contacting the compound according to Formula (X) with an oxidant.

In an exemplary embodiment, the leaving group Y in Formula (VII) is a halogen. In a preferred embodiment Y is chloro. In another exemplary embodiment according to this aspect of the invention, (L)_pM- in Formula (IV) is (L)₂Al—. In a particularly preferred embodiment, (L)_pM- is (CH₃)₂Al—.

The aromatic precursor according to Formula (VIII) can include substantially any useful phenol protecting group as R⁴. Preferred R⁴ groups are removed by a reaction that is a member selected from the group consisting of hydrolysis, hydrogenolysis, reduction, oxidation, nucleophilic attack, electrophilic attack and combinations thereof. In an exemplary embodiment R⁴ is —S(O)R³⁰. R³⁰ is preferably substituted or unsubstituted alkyl or substituted or unsubstituted aryl, and more preferably p-tolyl. In a still further preferred embodiment, the p-toluenesulfonyl group is removed by contacting the compound with a mixture comprising n-butyllithium, thereby producing the compound according to Formula (X).

IV. b.) i.) A. Organometallic Species of Formula (IV)

The metals, M, of use in the method of the invention include those metals that can carbometallate an alkyne component to produce a species according to Formula (IV). In an exemplary embodiment, metals include transition metals and aluminum. The metal can be formally neutral or it can be charged (e.g. an aluminate). The transition metal chemistry can be catalytic or stoichiometric. For example, the alkyne can be metalated by catalytic carbocupration using Cu(I) to form an adduct that is subsequently transmetalated to the corresponding zinc reagent.

The coordination number of M is satisfied by the bonding or coordination to the metal ion of the requisite number of organometallic ligands, such as Lewis base donors (e.g., halogen donors, oxygen donors, mercaptide ligands, nitrogen donors, phosphorous donors, and heteroaryl groups); hydrides; carbon ligands bound principally by σ-bonds (e.g., alkyls, aryls, vinyls, acyl and related ligands); carbon ligands bound by σ- and π-bonds (e.g., carbonyl complexes, thiocarbonyl, selenocarbonyl, tellurocarbonyl, carbenes, carbynes, σ-bonded aetylides, cyanide complexes, and isocyanide complexes); ligands bound through more than one atom (e.g., olefin complexes, ketone complexes, acetylene complexes, arene complexes, cyclopentadienyl complexes, π-allyl complexes); unsaturated nitrogen ligands (e.g., macrocyclic imines, dinitrogen complexes, nitric oxide complexes, diazonium complexes); and dioxygen complexes. Other useful combinations of metal ions and ligands will be apparent to those of skill in the art. See, for example, Collman J P et al. PRINCIPLES AND APPLICATIONS OF ORGANOTRANSITION METAL CHEMISTRY, University Science Books, 1987.

In an exemplary embodiment, the organometallic species according to Formula (IV) is a carboaluminated species. In an exemplary embodiment the carboaluminated species 54 is synthesized following the procedure outlined in Scheme VI: in which n is as defined above.

Method for the preparation of the carboaluminated species with an alkyl moiety bound to aluminum according to Formula (IV), including compound 54, are described in U.S. Pat. No. 6,545,184 to Lipshutz et al., and U.S. Patent Application No. 20050148675 to Lipshutz et al.; the disclosures of which are herein incorporated by reference.

In one aspect, the method of carboalumination utilizes a metal species, e.g., a zirconium or titanium complex, in a catalytic quantity, which means in an amount of less than 1 molar equivalent relative to the alkyne substrate 53. Catalysts for this reaction are referred to herein as “carboalumination catalysts”. For example, the catalyst can be present in amounts of 0.1 to 20 mole %, preferably from about 0.5 to about 5.0 mole % relative to the alkyne. It has been discovered that minimizing the amount of zirconium species present does not have a deleterious effect on the efficiency of the carboalumination. Thus, the invention provides a method of carboalumination, using a catalytic amount of a metal species, e.g., a zirconium or titanium species that provides the carboaluminated species in high yields.

An exemplary carboalumination catalyst of use in the present invention is Cp₂ZrCl₂. Those of skill in the art will recognize that numerous other metal-based catalysts, such as titanocenes and zirconocenes, are of use as carboalumination catalysts in the invention.

In this embodiment, the invention is based on recognition that the remaining organometallic carboalumination catalyst (e.g., the zirconium salts), rather than the potential organic impurities, is problematic in the coupling of carboaluminated alkyne (IV) and a quinone (e.g., 1 or 3) to form a compound of Formula (I) or Formula (II), and that minimization of the carboalumination catalyst allows for a shortened (“one pot”) route to the target ubiquinone. Thus, when a minimized amount of a zirconium or titanium species is used (e.g. ≦10 mole %), the carboaluminated product does not have to be separated prior to its being used in a coupling reaction with a quinone. Surprisingly, no marked degradation in the purity or quantity of the coupling product results from omitting the purification step.

In another exemplary embodiment, the carboalumination process is conducted in the presence of substoichiometric amounts of water, an alcohol (R^xOH) or methylaluminoxane (MAO), and in the presence of about 0.5 to 20 mole % of a coupling catalyst (e.g. a zirconium or titanium species as described above). Preferably the subsequent coupling reaction is carried out without prior removal of the carboalumination catalyst or the species derived thereof from the resulting vinyl alane. This allows conducting the carboalumination and the subsequent coupling as a “one pot” reaction, i.e. a reaction that is conducted in one vessel. The present methodology offers a convenient access to ubiquinone and ubiquinol analogs and offers the advantage of applicability to a technical scale.

The carboalumination reaction can yield mixtures of regioisomeric vinyl alanes, which in turn lead to mixtures of ubiquinone regioisomers in the subsequent cross coupling reaction with the C* methylene carbon of chloromethylated quinones according to Formula III. The factors influencing the regioselectivity of the carboalumination are well known to those skilled in the art. Those include for example the temperature, the nature of the solvent and of the carboalumination catalyst.

IV. b.) i.) B. Cross Coupling of Organometallic Species with Compounds of Formula (III)

In one aspect of the invention, compounds according to Formula (I) are synthesized following the general procedure outlined in Scheme VII.

In Scheme VII a substituted-methylene moiety according to Formula (III), wherein Z is a leaving group, and in which the substituents R¹, R², and R³ are as discussed above, is contacted with a carboaluminated species having a structure according to Formula (IV), wherein M, L, p and n are defined as above.

The coupling of compound (III) with a compound according to Formula (IV) affords the compound according to Formula (I). The two components are contacted in the presence of a coupling catalyst that is effective at catalyzing coupling between C* of the substituted methylene group in Formula (III), and the vinylic carbon attached to the metal on the compound according to Formula (IV).

IV. b.) i.) C. Cross Coupling Catalysts

In an exemplary embodiment, the coupling catalyst utilizes a species that includes a transition metal. Exemplary transition metal species of use as coupling catalysts include, but are not limited to, those metals in Groups IX, X, and XI. Exemplary metals within those Groups include Cu(I), Pd(0), Co(0) and Ni(0). Recent reports have demonstrated that catalyst couplings, using the appropriate reaction partners and based on metal catalysis, are quite general and can be used to directly afford known precursors (Naruta, J. Org. Chem., 45:4097 (1980); Eren, et al., J. Am. Chem. Soc., 110:4356 (1988) and references therein; Van Lient et al., Rec. Trav. Chim. Pays-Bays 113:153 (1994); Rüttiman et al., Helv. Chim. Acta, 73:790 (1990); Terao et al., J. Chem. Soc., Perkin Trans. 1:1101 (1978), Lipshutz et al., J. Am. Chem. Soc. 121:11664-11673 (1999); Lipshutz et al., J. Am. Chem. Soc. 118: 5512-5313 (1999)). In another exemplary embodiment, the metal is Ni(0).

The coupling catalyst can be formed by any of a variety of methods recognized in the art. In an exemplary embodiment in which the transition metal is Ni(0), the coupling catalyst is formed by contacting a Ni(II) compound with two equivalents of a reducing agent, reducing Ni(II) to Ni(0). In an exemplary embodiment, the Ni(II) compound is NiCl₂(PPh₃)₂. In yet another exemplary embodiment, the reducing agent is n-butyllithium. In yet another exemplary embodiment, the method of the invention includes contacting NiCl₂(PPh₃)₂, or a similar Ni species, with about two equivalents of a reducing agent (e.g., n-butyllithium), thereby reducing said NiCl₂(PPh₃)₂ to Ni(0). Alternatively, other readily available forms of Ni(0) can be employed (e.g., Ni(COD)₂).

The coupling catalyst can be a homogeneous or heterogeneous catalyst (Cornils B, Herrmann W A, APPLIED HOMOGENEOUS CATALYSIS WITH ORGANOMETALLIC COMPOUNDS: A COMPREHENSIVE HANDBOOK IN TWO VOLUMES, John Wiley and Sons, 1996; Clark J H, CATALYSIS OF ORGANIC REACTIONS BY SUPPORTED INORGANIC REAGENTS, VCH Publishers, 1994; Stiles A B, CATALYST SUPPORTS AND SUPPORTED CATALYSTS: THEORETICAL AND APPLIED CONCEPTS, Butterworth-Heinemann, 1987). In one exemplary embodiment, the coupling catalyst is supported on a solid material (e.g., charcoal, silica, etc.). In another exemplary embodiment, the coupling catalyst is a supported nickel catalyst (see, e.g., Lipshutz et al., Synthesis, 2110 (2002); Lipshutz et al., Tetrahedron 56:2139-2144 (2000); Lipshutz and Blomgren, J. Am. Chem. Soc. 121: 5819-5820 (1999); and Lipshutz et al., Inorganica Chimica Acta 296: 164-169 (1999).

The method of the invention is practiced with any useful amount of coupling catalyst effective at catalyzing coupling between the methylene carbon atom on the aromatic group or of the quinone moiety mentioned above, and the vinylic carbon attached to M on the compound according to Formula (IV). In an exemplary embodiment, the coupling catalyst is present in an amount from about 0.1 mole % to about 10 mole %. In an exemplary embodiment, the coupling catalyst is present in an amount from about 0.5 mole % to about 5 mole %. In an exemplary embodiment, the coupling catalyst is present in an amount from about 2 mole % to about 5 mole %.

The above mentioned coupling reaction can be carried out in all solvents known to those of skill in the art, suitable as solvents for transition metal catalyzed coupling reactions, e.g., ethers, such as THF, diethyl ether and dioxane; amines, e.g., triethylamine, pyridine and NMI; as well as other solvents, such as acetonitrile, acetone, ethyl acetate, DMA, DMSO, NMP and DMF. In a preferred embodiment, it is not required to completely remove the solvent in which the carboalumination was carried out, prior to the coupling.

The conditions of the coupling reaction can be varied. For example, the order of addition of reactants can be varied. In an exemplary embodiment, the substituted methylene moiety and carboaluminated species are contacted, and then the coupling catalyst is subsequently added. In an exemplary embodiment, the substituted methylene moiety and coupling catalyst are contacted, and then the carboaluminated species is subsequently added. In an exemplary embodiment, the coupling catalyst and carboaluminated species are contacted, and then the substituted methylene moiety is subsequently added.

The amount of the substituted methylene moiety relative to the alkyne employed in the prior carboalumination can also be varied. In an exemplary embodiment, the substituted methylene moiety, can be reacted in amounts ranging from 0.9 to 10 equivalents relative to the alkyne mentioned above. In another exemplary embodiment, the substituted methylene moiety can be reacted in amounts ranging from 0.9 to 5 equivalents, preferably from 0.9 to 2, and most preferably from 1.1 to 1.6 equivalents, relative to the alkyne mentioned above.

The coupling reaction of the present invention can be conducted under a variety of conditions. For example, the coupling reaction can be conducted at a temperature from −40° C. to 50° C. In an exemplary embodiment, the temperature of the coupling reaction can be room temperature. In another exemplary embodiment, the temperature of the carboalumination reaction can be from −30° C. to 0° C. In another exemplary embodiment, the temperature of the carboalumination reaction can be from about −25° C. to about −15° C.

The length of time for the coupling reaction can vary from 10 minutes to 10 hours. Typically, the lower the temperature at which the reaction is conducted, the longer the amount of time it takes for the reaction to go to completion. When the temperature is about 0° C., the reaction can be completed from about 30 minutes to about 3 hours.

A representative example for preparing a ubiquinone of Formula (I), starting with quinone 35 is set forth in Scheme VIII.

In Scheme VIII, the chloromethyl quinone 35 is contacted with the vinylalane 54 in the presence of a Ni(0) catalyst. The reaction affords the corresponding ubiquinone 7.

IV. b.) ii.) Synthesis of the Ubiquinol Analogs According to Formula (II)

In another aspect the present invention provides a method of making a compound of Formula (II), which includes, synthesizing a compound according to Formula (I) by one of the above methods, and reducing the intermediate, thereby forming a compound according to Formula (II). The procedure is outlined in Scheme IX, below.

In Scheme IX a ubiquinon analog according to Formula (I) is reduced to afford a hydroquinone according to Formula (II), in which the substituents R¹, R², and R³ and the integer n are as discussed above.

Reducing agents that can be used for this conversion are known in the art and include Zn reagents, peroxidisulfates (S₂O₈²⁻), and Sn reagents (e.g. SnCl₂). Alternatively the reduction can be accomplished using catalyic hydrogenation.

In another aspect of the invention compounds according to Formula (II) are synthesized following the procedure outlined in Scheme X: wherein Z is a leaving group and n, R¹, R², and R³ are as discussed as above. P¹ and P² are protecting groups.

In an exemplary embodiment Z is a halogen, such as chloro.

In another exemplary embodiment the protecting groups P¹ and P² include ethers formed between the phenol oxygen atom and substituted or unsubstituted alkyl groups (e.g. methoxy and ethoxy groups). Other useful protecting groups include sulfonic acid esters, methoxymethyl, benzyloxymethyl, methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl, methylthiomethyl, phenylthiomethyl, 2,2-dichloro-1,1-difluoroethyl, tetrahydropyranyl, phenacyl, p-bromophenacyl, cyclopropylmethyl, allyl, isopropyl, cyclohexyl, t-butyl, benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl, o-nitrobenzyl, 2,6-dichlorobenzyl, 4-(dimethylaminocarbonyl)benzyl, 9-anthrymethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl); silyl ethers (e.g., trimethylsilyl, t-butyldimethylsilyl); esters (e.g., acetate, levulinate, pivaloate, benzoate, 9-fluorenecarboxylate); carbonates (e.g., methyl, 2,2,2-trichloroethyl, vinyl, benzyl); phosphinates (e.g., dimethylphosphinyl, dimethylthiophosphinyl); sulfonates (e.g., methanesulfonate, toluenesulfonate, 2-formylbenzenesulfonate), and the like (see, e.g., Greene et al., PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, 3rd ed., John Wiley & Sons, New York, 1999). In an exemplary embodiment P¹ and P² are members independently selected from CH(O) and substituted or unsubstituted alkyl. In a preferred embodiment, the protecting groups P1 and P2 do not include a hydrophilic polymeric moiety selected from a polyether and a polyalcohol. In another preferred embodiment, the protecting groups P1 and P2 do not include a member selected from a labeling moiety, a targeting moiety and a drug moiety.

P1 and P2 are preferrably removed by a reaction that is a member selected from hydrolysis, hydrogenolysis, reduction, oxidation, nucleophilic attack, electrophilic attack and combinations thereof. In an exemplary embodiment at least one of the protecting groups P1 and P2 is —S(O)₂R³⁰ wherein R³⁰ is preferably substituted or unsubstituted alkyl or substituted or unsubstituted aryl, and more preferably p-tolyl. In a still further preferred embodiment, the p-toluenesulfonyl group is removed by contacting the compound with a mixture comprising n-butyllithium, thereby producing the compound according to Formula (II).

In Scheme X the Z-substituted-methylene moiety according to Formula (XII), is contacted with a carboaluminated species having a structure according to Formula (IV), wherein M, L, p, and n are as defined above to afford compound 55. The coupling conditions are similar to those described above for the synthesis of the ubiquinones according to Formula (I). In the last step the protecting groups are removed to afford the compound of Formula (II). Alternatively only one of the protecting groups can be removed, while the other remains intact.

In an exemplary embodiment, P¹ is a CH(O) moiety and P² is methyl, as shown in Scheme XI.

In Scheme XI the OCH(O) moiety of compound 56 is a protecting group that remains intact during the alkylation to produce compound 57. The CH(O) group is removed by hydrolytic cleavage to afford the resulting phenol 58, which can alternatively be oxidized to the corresponding ubiquinone.

Methods for the purification of the ubiquinones and ubiquinoles of the invention, are provided in U.S. Pat. No. 6,545,184 to Lipshutz et al., and U.S. Patent Application No. 20050148675 to Lipshutz et al., the disclosures of which are herein incorporated by reference.

The synthetic schemes set forth herein are intended to be exemplary of the synthesis of compounds of the invention. Those of skill in the art will recognize that many other synthetic strategies leading to compounds within the scope of the present invention are available. For example, by modification of the starting materials a compound having an ethoxy, rather than a methoxy group can be produced. Moreover, leaving and protecting groups discussed herein can be replaced with other useful groups having a similar function.

V. Pharmaceutical Compositions

In another aspect, the present invention provides a pharmaceutical composition comprising a compound of the invention or a pharmaceutically acceptable salt or solvate thereof, and a pharmaceutically acceptable carrier.

The compounds of the present invention can be prepared and administered in a wide variety of oral, parenteral and topical dosage forms. Thus, the compounds of the present invention can be administered by injection, that is, intravenously, intramuscularly, intracutaneously, subcutaneously, intraduodenally, or intraperitoneally. Also, the compounds described herein can be administered by inhalation, for example, intranasally. Additionally, the compounds of the present invention can be administered transdermally.

Pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, pills, capsules, soft-gel capsules, cachets, suppositories, and dispersible granules. A solid carrier can be one or more substances, which may also act as diluents, flavoring agents, binders, preservatives, tablet disintegrating agents, or an encapsulating material.

In powders, the carrier is a finely divided solid, which is in a mixture with the finely divided active component. In tablets, the active component is mixed with the carrier having the necessary binding properties in suitable proportions and compacted in the shape and size desired.

The powders and tablets preferably contain from 5% or 10% to 70% of the active ingredient. Suitable carriers are magnesium carbonate, magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose, a low melting wax, cocoa butter, and the like. The term “preparation” is intended to include the formulation of the active modulator with encapsulating material as a carrier providing a capsule in which the active component with or without other carriers, is surrounded by a carrier, which is thus in association with it. Similarly, cachets and lozenges are included. Tablets, powders, capsules, pills, cachets, and lozenges can be used as solid dosage forms suitable for oral administration.

For preparing suppositories, a low melting wax, such as a mixture of fatty acid glycerides or cocoa butter, is first melted and the active component is dispersed homogeneously therein, as by stirring. The molten homogeneous mixture is then poured into convenient sized molds, allowed to cool, and thereby to solidify.

Liquid form preparations include solutions, suspensions, and emulsions, for example, water or water/propylene glycol solutions, which may be contained in soft-gelatin capsules. For parenteral injection, liquid preparations can be formulated in solution in aqueous polyethylene glycol solution.

Aqueous solutions suitable for oral use can be prepared by dissolving the active component in water and adding suitable colorants, flavors, stabilizers, and thickening agents as desired. Aqueous suspensions suitable for oral use can be made by dispersing the finely divided active component in water with viscous material, such as natural or synthetic gums, resins, methylcellulose, sodium carboxymethylcellulose, and other well-known suspending agents.

Also included are solid form preparations, which are intended to be converted, shortly before use, to liquid form preparations for oral administration. Such liquid forms include solutions, suspensions, and emulsions. These preparations may contain, in addition to the active component, colorants, flavors, stabilizers, buffers, artificial and natural sweeteners, dispersants, thickeners, solubilizing agents, and the like.

The pharmaceutical preparation is preferably in unit dosage form. In such form the preparation is subdivided into unit doses containing appropriate quantities of the active component. The unit dosage form can be a packaged preparation, the package containing discrete quantities of preparation, such as packeted tablets, capsules, and powders in vials or ampoules. Also, the unit dosage form can be a capsule, tablet, cachet, or lozenge itself, or it can be the appropriate number of any of these in packaged form.

The quantity of active component in a unit dose preparation may be varied or adjusted from 0.1 mg to 10000 mg, more typically 1.0 mg to 1000 mg, most typically 10 mg to 500 mg, according to the particular application and the potency of the active component. The composition can, if desired, also contain other compatible therapeutic agents.

VI. Pharmaceutical Methods

In a further aspect, the invention provides a method for treating a condition, which is a member selected from a neurological disorder (e.g., a central nervous system disorder), a mitochondrial disease and a heart disease. The method includes administering to a subject in need thereof a therapeutically effective amount of a compound of the invention or a pharmaceutically acceptable salt or solvate thereof. In a preferred embodiment, the subject is a human.

In an exemplary embodiment, the neurological disorder is a member selected from Huntington's disease and Parkinson's disease. In another exemplary embodiment, the mitochondrial disorder is a member selected from progressive external opthalmoplegia, diabetis mellitus, deafness, Leber hereditary optic neuropathy, mitochondrial encephalomyopathy, lactic acidosis, stroke-like syndrome, myoclonic epilepsy, ragged-red fibers, Leigh syndrome, subacute sclerosing encephalopathy, neuropathy, ataxia, retinitis pigmentosa, ptosis, Kearns-Sayre syndrome and myoneurogenic gastrointestinal encephalopathy. Additional conditions and diseases, which may be treated using the compounds of the invention, are described in Bliznakov, E. G., Hunt, G. L. The Miracle Nutrient Coenzyme Q10; Elsevier/North-Holland Biomedical Press: New York, 1986 and in Sinatra, S. T. The Coenzyme Q10 Phenomenon; Keats Publishing, Inc.: New Canaan, 1998, as well as Coenzyme Q: biochemistry, bioenergetics, and clinical applications of ubiquinone; Lenaz, G., Ed.; Wiley: New York, 1985 and Coenzyme Q: molecular mechanisms in health and disease; Kagan, V. F., Quinn, P. J., Eds.; CRC Press: Boca Raton, 2001.

In one aspect, the compounds of the invention can be used to increase ATP generation in a mitochondrium by contacting the mitochondrium with the compound.

In another aspect, the compound of the invention is useful as a reference compound in an assay measuring electron transfer from a respiratory enzyme (e.g., human mitochondrial complex I, mitochondrial complex II and mitochondrial complex III) to a test compound.

The materials, methods and devices of the present invention are further illustrated by the examples that follow. These examples are offered to illustrate, but not to limit the claimed invention.

EXAMPLES

General

In the examples below, unless otherwise stated, temperatures are given in degrees Celsius (° C.); operations were carried out at room or ambient temperature, “rt,” or “RT,” (typically a range of from about 18-25° C.); evaporation of solvent was carried out using a rotary evaporator under reduced pressure (typically, 4.5-30 mm Hg) with a bath temperature of up to 60° C.; the course of reactions was typically followed by thin layer chromatography (TLC) and reaction times are provided for illustration only; melting points are uncorrected; products exhibited satisfactory ¹H-NMR and/or microanalytical data, yields are provided for illustration only; and the following conventional abbreviations are also used: mp (melting point), L (liter(s)), mL (milliliters), mmol (millimoles), g (grams), mg (milligrams), min (minutes), h (hours), RBF (round bottom flask).

The following chemicals were subjected to the following preparatory steps prior to use in the Examples. PCl₃ was refluxed for 3 h at 76° C. while slowly purging with dry argon to expel HCl, distilled at atmospheric pressure and stored in a sealed container under argon until needed. DMF, 2-propanol and benzene were used as supplied from Fisher chemicals. Solanesol, purified by column chromatography on SiO₂ with 10% diethyl ether/petroleum ether, was dried azeotropically with toluene or benzene immediately prior to use. THF was distilled from Na/benzophenone ketyl prior to use. n-BuLi was obtained as a 2.5 M solution in hexanes from Aldrich and standardized by titration immediately prior to use. Ethanol was 200 proof dehydrated, U.S.P. Punctilious grade. All other reagents were purchased from suppliers and used without further purification. Products were confirmed by ¹H NMR, ¹³C NMR, IR, LREIMS and HR-EI or HR-CI Mass Spectrometry. TLC and chromatographic solvents are abbreviated as follows: EA: ethyl acetate; PE: petroleum ether; DCM: dichloromethane.

Example 1

Synthesis of Compound 1

The synthesis of compound 1 consists of four distinct portions; the synthesis of the chloromethylated analog 33, carbalumination of an alkyne to afford the alane 54 (n=9), preparation of the Ni(0) coupling catalyst, and cross coupling of the alane 54 to 33.

1.1 Synthesis of 5-(chloromethyl)-3-methoxy-2-methylcyclohexa-2,5-diene-1,4-dione 33

1.1.a 1-(2,4-Dimethoxy-3-methylphenyl)ethanone

In a dry, argon-flushed, round bottom flask equipped with a stir bar, acetyl chloride (0.09 mL, 0.11 g, 1.32 mmol) was added to TiCl₄ (0.15 mL, 0.25 g 1.32 mmol) at −10° C. and stirred for 0.1 h. Once the flask cooled to −10° C., a solution of 2,6-dimethoxytoluene (0.18 g, 0.96 mmol) in distilled benzene (5 mL) was added over the course of 10 min with vigorous stirring. During the addition, the temperature was maintained at 0° C. The solution was stirred at 0° C. for 0.5 h, at which point it was complete. The reaction mixture was subsequently poured into a slurry of ice and HCl (1 M, 5 mL), extracted with ether (3×5 mL), washed with aqueous NaHCO₃ and brine, dried over Na₂SO₄, and concentrated down to afford a pale, yellow oil (0.14 g, 95%). The crude product was used in the subsequent step without further purification. Full spectral data for this compound has been reported (Knolker, H-J.; Frohner, W.; Reddy, K. R.; Synthesis 2002, 4, 557-564).

1.1. b 2,4-Dimethoxy-3-methylphenylacetate

In a dry, argon-flushed round bottom flask, recrystallized mCPBA (2.43 g, 14.0 mmol) was dissolved in distilled CH₂Cl₂ (15 mL). In a second, identical flask, the acetophenone (2.78 g, 11.74 mmol) and TsOH (0.10 g, 0.6 mmol) was dissolved in CH₂Cl₂ (5 mL) and cooled to 0° C. With vigorous stirring, the contents of the first flask were slowly transferred via cannula to the second flask. The resulting suspension was allowed to warm to rt and stirred for 4 h. When the reaction was complete according to TLC analysis (Rf=0.4, 10% ethyl acetate:hexanes), Na₂SO₃ (1 M, 20 mL) was added and stirred for 0.25 h to destroy any excess peracid. Additionally, saturated aqueous NaHCO₃ (20 mL) was added and the mixture was stirred for 0.25 h to neutralize. The organics were extracted with CH₂Cl₂ (3×30 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a red-orange oil. Distillation of the crude product afforded a light-yellow oil (2.2 g, 90%) that solidified in the refrigerator. Full spectral data for this compound has been reported (Knolker, H-J.; Frohner, W.; Reddy, K. R.; Synthesis 2002, 4, 557-564).

1.1.c 2,4-Dimethoxy-3-methylphenol

In a round bottom flask equipped with a stir bar, aryl acetate (5.2 g, 24.8 mmol) was dissolved in ethanol (20 mL) and stirred at rt. Over a period of 10 min, a solution of KOH (6.9 g, 123.8 mmol) in water (10 mL) was added and an orange-brown solution formed. The solution was stirred for 2-3 h, at which point TLC analysis (Rf=0.45, 33% ether:hexanes) showed the reaction had gone to completion, and the ethanol was evaporated in vacuo. The aqueous layer was acidified to pH=4 using HCl (6 M) and the organics were extracted with ether (3×50 mL), washed with brine, and dried over Na₂SO₄. Removal of the solvent and distillation in vacuo provided a clear oil (3.7 g, 88%) that solidified in the refrigerator. Full spectral data for this compound has been reported (Knolker, H-J.; Frohner, W.; Reddy, K. R.; Synthesis 2002, 4, 557-564).

1.1.d 2-Hydroxy-3,5-dimethoxy-4-methylbenzaldehyde

In a dry, argon-flushed round bottom flask, fresh trifluoroacetic acid and trifluoroacetic anhydride (1:1, 10 mL each) were mixed and cooled to 0° C. In a second identical flask, phenol (5.0 g, 30.0 mmol) and hexamethylenamine (6.25 g, 45.0 mmol) were weighed out, purged under an argon atmosphere, and cooled to 0° C. The pre-mixed TFA:TFAA solution was then slowly transferred to the second flask via cannula with vigorous stirring. Once the initial exotherm subsided, the reaction was warmed to rt. A water-jacket condenser was then attached to the flask and the mixture was heated to reflux for 45 h. The initially orange mixture turned red-black. When TLC analysis (Rf=0.3, 30% ether:hexanes) showed the reaction had gone to completion, the mixture was poured slowly into a flask containing a slurry of ice and aqu. NaHCO₃. Once the mixture was neutralized, the organics were extracted with ether (3×50 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a red-black solid. The solid was taken up in ether and pushed through a plug of silica to remove polymeric by-products. The organics were then concentrated down to afford light yellow needle-shaped crystals (4.6 g, 78%) taken on without further purification to the next step.

1.1.e 2,3,5-Trimethoxy-4-methylbenzaldehyde

In a dry, argon-flushed round bottom flask equipped with a stir bar, phenol (5.4 g, 27.4 mmol) and K₂CO₃ (11.4 g, 82.3 mmol) were added to acetone (30 mL) and stirred at 0° C. Me₂SO₄ (4.1 g, 3.1 mL, 32.9 mmol) was added to the reaction dropwise at 0° C. until the exotherm subsided, then the mixture was warmed to room temperature and heated to 40° C. for 8 h. Upon completion (TLC Rf=0.6, 30% ether:hexanes), the reaction was neutralized with HCl (1 M) and the organics were extracted with ethyl acetate (3×50 mL), washed with brine, dried over Na₂SO₄, and evaporated down to a brown oil. Flash column chromatography on silica gel with a solution of 25% ether:hexanes as eluant afforded a white, crystalline solid (5.26 g, 91%).

HRMS Calcd for C₁₁H₁₄O₄: 210.0884. Found: 210.0892. Ms m/z (%): 210(100), 195(60), 180(6), 167(12), 152(10), 137(11), 124(9), 109(12), 53(19). IR (KBr) cm⁻¹: 2939, 2856, 1682, 1599, 1470, 1407, 1386, 1333, 1134, 739, 629. ¹H NMR (CDCl₃) δ: 10.351 (s, 1H), 7.036(s, 1H), 3.954(s, 3H), 3.862(s, 3H), 3.846(s, 3H), 2.200(s, 3H). ¹³C NMR (CDCl₃) δ: 189.7, 154.7, 152.3, 151.6, 130.0, 127.2, 102.3, 62.8, 60.7, 56.0, 9.9.

1.1.f (2,3,5-trimethoxy-4-methylphenyl)methanol

In a round bottom flask equipped with a stir bar, aldehyde was dissolved in THF (5 mL) and cooled to 0° C. NaBH₄ (0.33 g, 8.94 mmol) was added and the reaction was allowed to warm to rt. The yellow solution turned clear as the aldehyde was reduced. After 4 h, no starting material was visible by TLC (product Rf=0.4, 35% ethyl acetate; hexanes). The flask was cooled back down to 0° C. and acidified to pH=2 using HCl (6 M). The resulting alcohol was extracted with ethyl acetate (3×30 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a clear oil (0.60 g, 96%) The crude product was carried on without further purification.

1.1. g 1-(Chloromethyl)-2,3,5-trimethoxy-4-methylbenzene

In a dry, argon-flushed round bottom flask equipped with a stir bar, freshly distilled DMF (0.65 g, 0.70 mL, 8.94 mmol) and freshly distilled PCl₃ (1.22 g, 0.78 mL, 8.94 mmol) were combined and stirred at 0° C. for 0.5 h until the two liquids had formed a white, crystalline solid (Vilsmeier's salt). In a second identical flask, the benzylic alcohol (0.64 g, 3.0 mmol) was dissolved in anhydrous THF (5 mL) and transferred to the first flask via cannula. The reaction was then allowed to warm to rt and stirred 2 h, after which no starting material remained according to TLC (Rf=0.8, 30% ethyl acetate:hexanes). A slurry of ice and sat. aqu. NaHCO₃ was prepared and the reaction mixture was carefully poured into the slurry in order to quench any remaining Vilsmeier reagent. The quench was stirred for 1 h. Once the reaction mixture was neutralized, the organics were extracted using ether (3×3.0 mL), washed with brine, dried with Na₂SO₄, and concentrated down to a yellow solid. The crude was pushed through a silica plug and concentrated down to afford a white solid (0.54 g of 96% pure material, 78%) taken on to the next step without further purification.

1.1. h 5-(chloromethyl)-3-methoxy-2-methylcyclohexa-2,5-diene-1,4-dione 33

In a round bottom flask covered in foil and equipped with a stir bar, ceric ammonium nitrate (6.31 g, 11.92 mmol) was dissolved in a solution of CH₃CN:H₂O (10:1, 100 mL) and stirred vigorously. Benzylic chloride (0.538 g, 2.33 mmol) dissolved in a minimal amount of CH₃CN was then added to the solution of CAN and allowed to stir at room temperature for 2-4 h until the reaction appeared to be complete by TLC (Rf=0.6, 20% ethyl acetate:hexanes). Ether (25 mL) and water (25 mL) were then added to the flask to create two distinct layers and the organics were extracted using ether (3×30 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a bright orange-red solid. Purification using flash column chromatography on silica gel with a gradient eluant starting with 100% hexanes and ending at 25% ethyl acetate:hexanes afforded the chloromethylquinone 33 as a yellow-orange oil (0.33 g, 70%). Care was taken to run the column quickly, in the absence of light, in order to limit decomposition. The purified chloromethylquinone 33 was then stored under an inert argon atmosphere at −78° C. until further use.

HRMS Calcd for C₉H₉O₃Cl: 200.0247. Found: 200.0240. Ms m/z(%): 200(15), 164(100), 157(15), 134(40), 109(20), 83(22), 67(50), 49(22). IR (KBr) cm⁻¹: 2949, 1657, 1610, 1447, 1379, 1292, 1204, 1226, 1009, 935, 872, 737, 673, 490. ¹H NMR(CDCl₃) δ: 6.822(s, 1H), 4.394(d, J=1.6, 2H), 4.022(s, 3H), 1.961(s, 3H). ¹³C NMR (CDCl₃) δ: 8.76, 39.08, 61.05, 129.53, 133.79, 141.86, 155.80, 182.80, 187.71.

1.2 Synthesis of the Alane 54 (Carboalumination)

To a dry, argon purged 25 mL round bottom flask was added Cp₂ZrCl₂ (0.011 g, 0.05 mmol) and DCE (0.5 mL). The flask was sealed under argon and cooled to 0° C. Me₃Al (0.76 mL, 1.5 mmol) was added dropwise, followed by MAO (10% w/w solution in toluene, 44 μL, 0.10 mmol) and the solution was allowed to age 0.5 h. Solanesol alkyne (0.727 g, 90% purity, 0.654 g, 10 mmol) dissolved in DCE (0.5 mL) was added to the reaction flask at 0° C. and the pale yellow solution was allowed to warm to rt. After 4-8 h, the solution turned a bright amber-yellow color and the alkyne was entirely consumed according to TLC (product Rf=0.9, 5% ether:p.ether) to afford the alane 54 (n=9). The solvent was then removed in vacuo, replaced with distilled THF (1.0 mL), and the flask was cooled to −20° C.

1.3 Preparation of the Ni(0) Catalyst

In a separate flask, n-BuLi (2.7 M solution, 30 μL, 0.08 mmol) was added to a solution of NiCl₂(PPh₃)₂ (0.027 g, 0.04 mmol) in THF (0.5 mL). The initially gray, heterogeneous solution of Ni(II) turned red-black upon reduction. This slurry was immediately transferred to the flask containing the vinyl alane from step 1.2.

1.4 Cross Coupling of Alane 54 with Compound 33

In another flask, 5-(chloromethyl)-3-methoxy-2-methylcyclohexa-2,5-diene-1,4-dione (0.10 g, 0.50 mmol) was dissolved in THF (0.5 mL), cooled to 0° C., and added to the flask containing the vinyl alane. The coupling was allowed to stir at −20° C. for 1-2 h without exposure to light, at which point the reaction had gone to completion. At this stage, two different methods could be employed to work up and isolate the product. In the first method, the reaction was diluted with ether and poured over a plug of anhydrous Na₂SO₄ and silica. The bright yellow organics were concentrated in vacuo to a crude orange-brown oil, dissolved in pet. ether (20 mL) and added to another round bottom flask containing a heterogeneous mixture of zinc dust (0.065 g, 1.0 mmol) in AcOH:H₂O (0.5 mL: 10 mL). This was stirred at rt for 4 h allowing the quinone to reduce to the hydroquinone. Once the reduction was complete according to TLC (R_f=0.3, 5% ethyl acetate:hexanes) the ether layer containing the hydroquinone was transferred via cannula to an argon-flushed separatory funnel. The product washed several times with degassed sat. aq. NaHCO₃ to remove any residual acetic acid. Concentration in vacuo and purification using flash column chromatography on silica gel under argon in a gradient, degassed solvent system of 0-25% ethyl acetate:hexanes afforded the pure reduced product as a clear oil (0.105 g, 23% (2 steps)). The oil was then dissolved in CH₃CN:H₂O (15 mL: 5 mL) and CAN (0.27 g, 0.5 mmol) was added at rt. The orange solution was allowed to stir for 1 h without exposure to light, at which point the oxidation was complete. Purification using flash column chromatography on silica gel with 10% ethyl acetate:hexanes afforded compound 1 as a bright, orange-yellow oil (0.084 g, 19% (3 steps)). During purification, care was taken to avoid exposure of the product to light.

The second simpler and higher yielding method involved warming the reaction to rt once the coupling was complete. After several hours of stirring at rt, the quinone was fully reduced in situ to the hydroquinone. The entire reaction mixture was then diluted with ether and poured over a plug of silica. The silica was rinsed several times more with ether, and the organics were concentrated in vacuo to afford a yellow oil. Purification using flash column chromatography on silica gel under argon in a gradient, degassed solvent system of 0-25% ethyl acetate:hexanes afforded the pure reduced product as a clear oil (0.214 g, 49%). This was then subjected to the same oxidation described in the first method. Purification using flash column chromatography on silica gel with 10% ethyl acetate:hexanes afforded compound 1 as a bright orange-yellow oil (0.17 g, 39% (3 steps), R_f=0.75, 10% ethyl acetate:hexanes). It should be noted that the R_f of the oxidized final product is virtually identical to the R_f of the quenched vinyl alane byproduct, making direct isolation of the coupled product difficult. The final product was stored under an argon atmosphere at −78° C. in the absence of light to minimize decomposition.

HRMS Calcd for C₅₈H₈₈O₃: 832.6701. Found: 832.6733. Ms m/z (%): 835(10), 684(8), 688(31), 410(76), 327(31), 259(50), 161(6), 135(14), 109 (19). IR (KBr) cm⁻¹: 2961, 2922, 2852, 1655, 1610, 1446, 1377, 1298, 1196, 1128, 1008, 843. ¹H NMR(CDCl₃) δ: 6.437 (s, 1H), 5.153-5.105 (m, 10H), 3.994 (s, 3H), 3.110 (d, J=7.2 Hz, 2H), 2.087-1.942 (m, 39H), 1.688 (s, 6H), 1.632-1.582 (m, 27H). ¹³C NMR (CDCl₃) δ: 188.82, 183.76, 156.20, 146.66, 140.18, 135.66, 135.28, 135.12, 132.29, 131.44, 129.06, 125.23, 124.59. 124.44, 123.95, 118.01, 60.99, 40.22, 39.94, 32.18, 27.18, 26.89, 26.65, 26.91, 23.64, 17.89, 16.35, 16.21, 8.78. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1038, −1350. Regioisomer ratio: about 88:12, about 6% hydroquinone impurity.

Example 2

Synthesis of Compound 2

2.1. Synthesis of 5-(chloromethyl)-2,3-dimethylcyclohexa-2,5-diene-1,4-dione 34

2.1.a 1,4-Dimethoxy-2,3-dimethylbenzene

In a round bottom flask equipped with a stir bar, hydroquinone (3.1 g, 22.3 mmol) was dissolved in ethanol (95%, 15 mL) and cooled to 0° C. A solution of Me₂SO₄ (5.7 mL, 6.3 g, 66.9 mmol) and aqueous NaOH (2.4 g, 60.0 mmol in 10 mL H₂O) was then added dropwise to the flask of hydroquinone, turning the solution dark red. Once the exotherm resided, the solution was allowed to warm to rt and stirred an additional 2-4 h, until the reaction was complete according to TLC analysis (product Rf=0.75, 20% ethyl acetate:hexanes). The solution was acidified to pH=3 with HCl (6 M). The organics were extracted with ethyl acetate (3×30 mL), washed with brine, dried with Na₂SO₄, and concentrated down to a red oil. Flash column chromatography on silica gel in a solution of 10% ethyl acetate:hexanes afforded the methoxy-protected hydroquinone as a white crystalline solid (3.37 g, 90%). R_f=0.4, 15% ethyl acetate:hexanes). Full spectral data for this compound has been reported previously (Lipshutz, B. H.; Kim, S-k.; Mollard, P.; Stevens, K. L. Tetrahedron, 1998, 54, 1241-1253).

2.1.b 1-(chloromethyl)-2,5-dimethoxy-3,4-dimethylbenzene

In a round bottom flask, methoxy-protected hydroquinone (1.10 g, 6.62 mmol) was dissolved in conc. HCl and stirred at rt. ZnCl₂ (0.90 g, 6.62 mmol) and paraformaldehyde (0.27 g, 7.9 mmol) were then added and stirred at rt. After 2 h, water was added to the flask and the organics were extracted with ether (3×30 mL), dried over Na₂SO₄, and concentrated down to a green-brown solid. Flash column chromatography on silica gel in a solution of 2% ether:hexanes afforded an off-white solid that contained a 4:1 mixture of the inseperable mono- and dichloromethylquinone (1.12 g, 91%). This mixture was taken on to the next step without further purification.

2.1.c 5-(chloromethyl)-2,3-dimethylcyclohexa-2,5-diene-1,4-dione (34)

In a 200 mL round bottom flask covered with foil and equipped with a stir bar, ceric ammonium nitrate (13.0 g, 28.0 mmol) was dissolved in a solution of CH₃CN:H₂O (50 mL:2.5 mL) and stirred at rt. To this was added benzylic chloride (1.5 g, 7.0 mmol). The solution was allowed to stir at rt for 4 h, at which point the no starting material remained according to TLC (product Rf=0.6, 20% ether:hexanes). Ether (50 mL) and water (50 mL) were added to the flask to separate the aqueous and organic layers. The product was extracted with ether (3×20 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a red oil. Flash column chromatography on silica gel in a solution of 2% ether:hexanes as eluant afforded the chloromethylquinone 34 as a yellow-orange oil that solidified in the refrigerator (0.52 g, 40%). Care was taken to minimize exposure to light in order to limit decomposition.

2.2. Synthesis of Compound 2

Compound 2 was prepared from the chloromethyl analog 34 and the alane 54 (n=9) following the cross coupling procedures outlined in Example 1. The following reagents were used in the specified amounts, 5-(chloromethyl)-2,3-dimethylcyclohexa-2,5-diene-1,4-dione 34 (0.10 g, 0.50 mmol), solanesyl propyne (0.489 g, 0.75 mmol), Cp₂ZrCl₂ (0.011 g, 0.05 mmol), AlMe₃ (0.56 mL, 2 M solution in toluene, 1.12 mmol), MAO (0.025 mL, 0.0022 g, 0.04 mmol), NiCl₂(PPh₃)₂ (0.027 g, 0.04 mmol), THF (2 mL), nBuLi (30 μL, 2.5 M solution in hexanes, 0.08 mmol). Flash column chromatography on silica gel in 2% ether:hexanes afforded 2 as a yellow solid (0.26 g, 59% (two steps), R_f=0.75, 13% ether:hexanes).

HRMS Calcd for C₅₈H₈₈O₂; 816.6757. Found: 816.6784. Ms m/z (%): 816(5), 190(14), 188(100), 135(10), 93(18), 81(37), 69(55). IR (KBr) cm⁻¹: 2964, 2922, 2853, 1649, 1616, 1448, 1383, 1317, 1101, 910, 843, 735, 650. ¹H NMR (CDCl₃) δ; 6.474 (t, J=1.6, 1H), 5.166-5.082 (m, 10H), 3.127 (d, J=7.2 Hz, 2H), 2.106-1.970 (m, 42H), 1.687 (s, 6H), 1.630-1.579 (m, 27H). ¹³C NMR (CDCl₃) δ: 187.98, 187.84, 148.11, 141.13, 140.73, 139.87, 135.58, 135.09, 132.18, 131.41, 124.59, 124.44, 123.98, 118.28, 39.93, 27.65, 26.88, 26.64, 25.90, 17.88, 16.32, 16.21, 12.6, 12.4. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1211, −1357. Regioisomeric ratio, 92:8, 15% hydroquinone impurity.

Example 3

Synthesis of Compound 7

3.1. Synthesis of 5-(chloromethyl)-2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione 35

3.1. a 1,4-dimethoxy-2,3,5-trimethylbenzene

In a round bottom flask equipped with a stir bar, hydroquinone (2.0 g, 13.2 mmol) was dissolved in ethanol (95%, 15 mL) and cooled to 0° C. A solution of Me₂SO₄ (3.4 mL, 3.7 g, 39.5 mmol) and aqu. NaOH (2.4 g, 60.0 mmol in 10 mL H₂O) was then added dropwise to the flask of hydroquinone, turning the solution dark red. Once the exotherm resided, the solution was allowed to warm to rt and stirred an additional 2-4 h, until the reaction was complete according to TLC analysis (product Rf=0.75, 20% ethyl acetate:hexanes). The solution was acidified to pH=3 with HCl (6 M). The organics were extracted with ethyl acetate (3×30 mL), washed with brine, dried with Na₂SO₄, and concentrated down to a red oil. Flash column chromatography on silica gel in a solution of 10% ethyl acetate:hexanes afforded the methoxy-protected hydroquinone as a white crystalline solid (2.1 g, 88%). Full spectral data for this compound has been reported (Lipshutz, B. H.; Kim, S-k.; Mollard, P.; Stevens, K. L. Tetrahedron, 1998, 54, 1241-1253).

3.1. b 1-(Chloromethyl)-2,4-,dimethoxy-3,4,6-trimethylbenzene

In a round bottom flask, methoxy-protected hydroquinone (1.30 g, 7.2 mmol) was dissolved in conc. HCl and stirred at rt. ZnCl₂ (1.1 g, 8.0 mmol) and paraformaldehyde (0.50 g, 14.4 mmol) were then added and stirred at rt. After 2 h, water was added to the flask and the organics were extracted with ether (3×30 mL), dried over Na₂SO₄, and concentrated down to a green-brown solid. Flash column chromatography on silica gel in a solution of 2% ether:hexanes afforded an off-white solid that contained a 4:1 mixture of the inseperable mono- and dichloromethylquinone (1.50 g, 90%). This mixture was taken on to the next step without further purification. Full spectral data for this compound has been reported (Lipshutz, B. H.; Kim, S-k.; Mollard, P.; Stevens, K. L. Tetrahedron, 1998, 54, 1241-1253).

3.1. c 5-(Chloromethyl)-2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione 35

In a 200 mL round bottom flask covered with foil and equipped with a stir bar, ceric ammonium nitrate (9.29 g, 20.0 mmol) was dissolved in a solution of CH₃CN:H₂O (50 mL:2.5 mL) and stirred at rt. To this was added benzylic chloride (1.15 g, 5.0 mmol). The solution was allowed to stir at rt for 4 h, at which point no starting material remained according to TLC (product Rf=0.6, 20% ether:hexanes). Ether (50 mL) and water (50 mL) were added to the flask to separate the aqueous and organic layers. The product was extracted with ether (3×20 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a red oil. Flash column chromatography on silica gel in a solution of 2% ether:hexanes as eluant afforded the chloromethylquinone 35 as a yellow-orange oil that solidified in the refrigerator (0.90 g, 78%). Full spectral data for this compound has been reported (Lipshutz, B. H.; Kim, S-k.; Mollard, P.; Stevens, K. L. Tetrahedron, 1998, 54, 1241-1253).

3.2. Cross Coupling of the Alane 54 (n=9) and Compound 35

Compound 7 was synthesized using the cross coupling procedures outlined in Example 1. The amounts of reagents were as follows, solanesyl propyne (0.700 g, 1.1 mmol), Cp₂ZrCl₂ (16.1 mg, 0.055 mmol), DCE (2 mL), H₂O (0.05 μL), NiCl₂(PPh₃)₂ (35 mg, 0.055 mmol), THF (3.0 mL), nBuLi (26.2 μL, 0.11 mmol), compound 35 (109.15 mg, 0.55 mmol). Flash chromatography using silica gel treated with a very small amount of Et₃N (0.25%) and a gradient hexanes:Et₂O solvent system (100% hexanes to 95%:5% hexanes:Et₂O) yielded 352 mg of an orange oil (77.0%).

HRMS Calcd for C₅₉H₉₀O₂: 830.6923. Found: 830.6940. Ms m/z (%): 831(10), 286(3), 243(3), 219(8), 203(94), 165(23), 69(100). IR (KBr) cm⁻¹: 2964, 2922, 2853, 1649, 1616, 1448, 1383, 1317, 1101, 910, 842, 735, 650. ¹H NMR (CDCl₃) δ: 5.10 (m, 9H), 4.96 (t, J=1.2 Hz, 1H), 3.20 (d, J=7.2 Hz, 2H), 2.10-1.93 (m, 42H), 1.75 (s, 3H), 1.68 (s, 3H), 1.64-1.56 (m, 30H), ¹³C NMR (CDCl₃) δ: 187.9, 187.0, 143.2, 140.4, 140.3, 137.1, 135.2, 135.0, 131.3, 124.5, 124.3, 124.2, 123.9, 119.5, 39.8, 26.8, 26.7, 26.5, 25.8, 25.6, 17.7, 16.4, 16.1, 12.4, 12.2. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1297. Regioisomeric ratio: 94:6, 3% hydroquinone impurity.

Example 4

Synthesis of Compound 9

4.1. Synthesis of 2-(chloromethyl)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione 36

4. 1.a 1,3-Dimethoxy-2,5-dimethylbenzene

A round bottom flask equipped with a stir bar was flame-dried, argon-flushed, and charged with anhydrous THF (100 mL). Elemental potassium (6.44 g, 165.0 mmol) was then weighed out in mineral oil and added to a beaker of hexanes to wash the oil off. While under hexanes, the metal was cut into 0.5 cm×0.5 cm squares and added to the flask with THF. Once all the metal was added, the flask was sealed under positive argon pressure with two septa, copper wire, Teflon tape, and parafilm. The flask was cooled to 0° C. in an ice bath. In a second dry, argon-purged flask, trimethoxytoluene (20.0 g, 110.0 mmol) was dissolved in anhydrous THF (20 mL) and transferred to the first flask via cannula. The flask was then placed into a sonicator for 24 h at room temperature. When all starting material was consumed according to TLC analysis (product Rf=0.5, 10% ethyl acetate:hexanes), the reaction was removed from the sonicator, placed on a stir plate, and recooled to 0° C. MeI (9.1 mL, 148.0 mmol) was then added via syringe and stirred for 6 h. The reaction mixture underwent an immediate color change from brown-orange to white, then back to brown. The reaction was worked up by first removing any large, undissolved metal pieces from the mixture, then slowly adding isopropyl alcohol dropwise. Once all the metal was quenched, water was added to the reaction to dissolve up the salts. The organics were extracted using ethyl acetate (4×200 mL), dried over Na₂SO₄ and concentrated down to a brown oil. The product was purified by flash column chromatography on silica gel in 100% petroleum ether to afford pure, white crystals (14.0 g, 77%). Full spectral data for this compound has been reported (Azzena, U. et al., J. Org. Chem. 1990, 55, 5386-5390).

4.1. b 2,4-Dimethoxy-3,6-dimethylbenzaldehyde

In a dry, argon-flushed, round bottom flask equipped with a stir bar, 3,5-methoxy-4-methyltoluene (16.8 g, 101.0 mmol) was dissolved in freshly distilled DMF (10.5 mL, 16.7 g, 111.0 mmol) and cooled to 0° C. Freshly distilled POCl₃ (8.52 mL, 15.0 g, 111.0 mmol) was added via syringe and the reaction was allowed to warm to rt for 1.5 h before heating to 45° C. for 18 h. Once the starting material was consumed according to TLC analysis (product Rf=0.70, 10% ether:p.ether), the reaction was cooled to 0° C. and quenched slowly with sat. NaHCO₃. The organics were extracted using ethyl acetate (3×200 mL), washed with brine, dried over Na₂SO₄ and concentrated down to an off-white solid. The product was purified by flash column chromatography on silica gel in a 5% ethyl acetate:hexanes solvent system to afford aldehyde as a white crystalline solid (18.0 g, 92%). Full spectral data for this compound has been reported (Cresp, T. et al., Australian J. of Chem. 1972, 25(10) 2167).

4.1.c 2-Hydroxyl-4-methoxy-3,6-dimethylbenzaldehyde

In a dry, argon-flushed, 500 mL round bottom flask equipped with a stir bar, 3,5-methoxy-1,4-methylbenzaldehyde (15.8 g, 80.9 mmol) was dissolved in anhydrous toluene (50 mL). In a second dry, argon-purged flask, AlCl₃ (12.9 g, 97.0 mmol) was suspended in anhydrous toluene (50 mL) and stirred at 0° C. The contents of the first flask were then transferred to the second flask via cannula. Immediately after the substrate was added to the AlCl₃ suspension, a thick red paste formed and was stirred at 0° C. for 8 hours. Once the starting material was consumed according to TLC analysis (product Rf=0.4, 25% ether:p. ether), the reaction was quenched slowly by adding a sat. citric acid solution (200 mL) to the reaction flask at 0° C. Several hours of stirring were required to fully break up the aluminum salts. The organics were then extracted with ethyl acetate (3×200 mL), washed with brine, dried over Na₂SO₄ and concentrated down to a yellow solid. The crude product was recrystallized from petroleum ether or purified by flash column chromatography on silica gel in a 10% ethyl acetate:hexanes solvent system to afford phenol (12.7 g, 75% yield) as yellow needle-shaped crystals. Full spectral data for this compound has been reported (Cresp, T. et al., Australian J. of Chem. 1972, 25(10) 2167).

4.1.d 2-(Hydroxymethyl)-5-methoxy-3,6-dimethylphenol

In a round bottom flask equipped with a stir bar, aldehyde (0.40 g, 2.2 mmol) was dissolved in THF (15 mL) and stirred at 0° C. To this was added NaBH⁴ (0.17 g, 4.4 mmol). The heterogeneous mixture was allowed to warm to rt and stirred for 4 h, at which time no starting material remained according to TLC analysis (product Rf=0.4, 60% ethyl acetate:hexanes). Excess NaBH₄ was quenched by slowly adding HCl (6 M) dropwise to the reaction until the pH was approximately 2, then solid NaCl (0.5 g, 8.55 mmol) was added to the mixture and stirred for 5-10 minutes. The organics were then extracted with chloroform (3×15 mL), dried over Na₂SO₄, and concentrated down to a clear, colorless oil (0.40 g, 95%). No further purification was necessary or possible due to the sensitive nature of the substrate.

4.1.e 2-(Hydroxymethyl)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione

In a round bottom flask equipped with a stir bar and covered with aluminum foil to decrease exposure to light, freshly prepared potassium nitrosodisulfonate (1.39 g, 5 mmol) was dissolved in an aqueous pH 5.8 phosphate buffer (20 mL). To this rapidly stirring heterogeneous mixture was added crude diol (0.30 g, 1.67 mmol) dissolved in acetone (10 mL). The reaction was allowed to run for 3-4 h until the diol was completely consumed according to TLC analysis (product Rf=0.3, 25% ethyl acetate:hexanes). Brine (10 mL) and chloroform (25 mL) were added to the reaction flask and stirred for 10 minutes, after which the organics were extracted with more chloroform (3×30 mL), washed with brine (30 mL), dried over Na₂SO₄, and concentrated down to afford a thick red-orange oil containing large amounts of polymeric byproducts along with the sensitive hydroxymethylquinone. This highly impure, crude material was dried thoroughly and taken directly into the next step without further purification or exposure to light.

4.1.f 2-(Chloromethoxy)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione 36

In a flame dried, argon-flushed, round bottom flask equipped with a stir bar and covered with foil, freshly distilled PCl₃ (0.7 mL, 8 mmol) was added via syringe to freshly distilled DMF (0.62 mL, 0.8 mmol) that had been cooled to 0° C. After 0.25 h, the liquids solidified into a white crystalline salt (Vilsmeier's salt) and stirring ceased. In a second dried, argon-flushed round bottom flask, the crude hydroxymethylquinone (1.21 g, 6.7 mmol) was dissolved in anhydrous THF (10 mL). This solution was transferred via cannula to the first flask containing the solid salt, and the reaction was then allowed to warm to rt, Eventually the white salt was sufficiently dissolved and stirring resumed. After several hours the starting material was entirely consumed according to TLC (product Rf=0.20, 20% ether:hexanes), and the flask was again cooled to 0° C. Sat. NaHCO₃ was added until all of the residual Vilsmeier salt was quenched and the reaction pH was neutral. The organics were extracted with ether (3×15 mL), washed with brine, dried with Na₂SO₄, and concentrated down to a thick, red oil. The resulting chloromethylquinone was purified by flash column chromatography on silica gel in a gradient solvent system starting with 100% hexanes and ending with 10% ethyl acetate:hexanes to afford 36 as a pure orange-red oil (0.13 g, 40% over two steps). The work up and purification were done in the absence of light, the column was run quickly to avoid excess decomposition on the silica, and the final product was stored under argon at −78° C.

HRMS Calcd for C₁₀H₁₁O₃Cl: 214.0392. Found: 214.0397. Ms m/z (%): 214(74), 186(40), 179(45), 171(24), 151(73), 123(60), 91(36), 83(95), 67(73), 53(100). IR (KBr) cm⁻¹: 2966, 1655, 1444, 1375, 1282, 1256, 1147, 970, 761. ¹H NMR (CDCl₃) δ; 4.456 (s, 2H), 4.002 (s, 3H), 2.152 (s, 3H), 1.98 (s, 3H). ¹³C NMR (CDCl₃) δ: 185.78, 183.41, 155.94, 142.39, 138.51, 128.84, 60.99, 35.66, 11.88, 8.95.

4.2. Cross Coupling of the Alane 54 (n=9) and Compound 36

Compound 9 was prepared from the chloromethyl analog 36 and the alane 54 (n=9) following the cross coupling procedures outlined in Example 1. The following reagents were used in the specified amounts: solanesyl propyne (1.25 g, 1.94 mmol). Cp₂ZrCl₂ (0.025 g, 0.087 mmol), AlMe₃ (3.5 mL, 2.0 M in hexanes, 2.91 mmol), DCE (3 mL), H₂O (0.05 μL), NiCl₂(PPh₃)₂ (0.035 g, 0.055 mmol), nBuLi (48 μL, 2.25 M in hexanes, 0.11 mmol), 2-(chloromethoxy)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione (0.235 g, 1.1 mmol), THF (2 mL). Purification using flash column chromatography on silica gel in a gradient solvent system of 0-5% ethyl acetate:hexanes afforded the pure product as a bright orange-red oil (0.363 g, 39% (two steps), R_f=0.80, 10% ethyl acetate:hexanes).

HRMS Calcd for C₅₉H₉₀O₃: 846.6886. Found: 846.6889. Ms m/z (%): 849(21), 301(4), 219(87), 203(5), 181(29), 137(10), 121(13), 93(19), 69(19). IR (KBr) cm⁻¹: 2966, 2926, 2852, 1651, 1614, 1447, 1375, 1288, 1265, 1146, 1105, 964, 739. ¹H NMR(CDCl₃) δ: 5.137-5.051 (m, 9H), 4.937 (t, J=6.8 Hz, 1H), 3.962 (s, 3H), 3.192 (d, J=6.8 Hz, 2H), 2.104-1.944 (m, 42H), 1.751 (s, 3H), 1.687 (s, 3H), 1.630-1.584 (m, 27H). ¹³C NMR (CDCl₃) δ: 188.1, 184.2, 155.6, 143.5, 138.9, 137.5, 135.4, 135.2, 135.1, 131.4, 128.8, 124.6, 124.5, 124.4, 124.1, 119.4, 61.0, 40.0, 31.8, 27.0, 26.9, 26.7, 25.9, 25.9, 22.9, 17.9, 16.5, 16.2, 14.3, 11.9, 9.1. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1223, −1467. Regioisomer ratio: 96:4

Example 5

Synthesis of Compound 9a

Compound 9a was synthesized using the procedures outlined in Example 4, with the difference that the alane 54 (n=9) in the cross coupling reaction is replaced with a shorter carboaluminated species 54, wherein n is 3.

HRMS Calcd for C₂₉H₄₂O₃: 438.3143. Found: 438.3134. Ms m/z (%): 438(19). 301(8), 259(5), 233(30), 219(57), 203(7), 181(23), 165(4), 69(100). ¹H NMR (CDCl₃) δ: 5.099 (m, 3H), 4.961 (t, J=7 Hz, 1H), 3.969 (s, 3H), 3.199 (d, J=6.8 Hz, 2H), 2.089-1.950 (m, 15H), 1.750 (s, 3H), 1.683 (s, 3H), 1.586-1.566 (m, 12H). ¹³C NMR (CDCl₃) δ: 188.1, 184.2, 155.6, 143.5, 138.9, 137.4, 135.3, 135.1, 131.4, 128.8, 124.6, 124.3, 124.1, 119.3, 60.9, 39.9, 31.8, 26.9, 26.8, 26.6, 25.9, 25.8, 22.9, 17.9, 16.49, 16.2, 14.3, 11.9, 9.0.

Example 6

Synthesis of Compound 11

6.1. Synthesis of 2-(chloromethyl)-6-methoxy-3,5-dimethylcyclohexa-2,5-diene-1,4-dione (37)

6.1.a 2,6-Dimethylcyclohexa-2,5-diene-1,4-dione

In a three-neck round bottom flask equipped with a stir bar, 1-bromo-2,3-dimethylphenol (2.19 g, 10.89 mmol) and CuCl₂-2H₂O (5.55 g, 32.69 mmol) were dissolved in DMF (50 mL, reagent grade). A reflux condenser was attached to the middle neck, and a septum was fastened to each of the outer necks, with needles inserted to deliver a constant flow of oxygen to the vented reaction flask. The reaction was heated to 60° C. for 16 h. If the reaction was not complete at this point, another equivalent of CuCl₂-H₂O was added and the mixture was stirred for an additional 16 h. When all starting material had been consumed according to TLC (Rf=0.25, 10% ethyl acetate:hexanes), the organics were extracted with ether (3×50 mL), and washed with a saturated LiCl solution to remove DMF. The combined organics were dried with Na₂SO₄ and concentrated down to a bright orange-yellow solid. The product was purified by flash column chromatography on silica gel with a 5% ethyl acetate:hexanes eluant to afford pure, bright yellow needle-shaped crystals (1.31 g, 88%). Full spectral data for this compound has been reported (Iyer, S.; Liebeskind, L. S.; J. Am. Chem. Soc. 1987, 109, 2759-2770).

6.1.b 3,5-Dimethyl-2,6-diacetoxyphenylacetate

In a dry, argon-flushed round bottom flask equipped with a stir bar, 2,2-dimethylbenzoquinone (0.20 g, 1.47 mmol) was dissolved in distilled acetic anhydride (3.0 mL) and cooled to 0° C. Triflic acid (0.10 mL, 0.74 mmol) was then added via syringe slowly. The reaction exothermed and the initial yellow color changed to dark red. After allowing the reaction to warm to room temperature, TLC analysis (Rf=0.45, 60% ethyl acetate:hexanes) showed that all starting material had been consumed. A second flask containing a slurry of ice and sat. NaHCO₃ was prepared and the contents of the reaction flask were slowly poured directly into the second flask to quench out any excess acid. Once neutralized, the organics were extracted using ethyl acetate (3×10 mL), washed with brine, and dried over Na₂SO₄ affording a dark red-black solid. The crude product was purified using flash column chromatography on silica gel with a 30% ethyl acetate:hexanes solution as eluant to afford triacetate as a white crystalline solid (0.35 g, 85%). Full spectral data for this compound has been reported (Yadav, J. et al., Tet. Lett., 2004, 6039-6041).

6.1. c 1,2,4-Trimethoxy-3,5-dim ethylbenzene

In a round bottom flask equipped with a stir bar, triacetate (10.2 g, 36.3 mmol) was dissolved in ethanol (50 mL, reagent grade). A second solution of sat. aqueous NaOH (10 mL) and Me₂SO₄ (5.0 mL, 5.4 g, 43.2 mmol) was prepared. The triacetate solution was cooled to 0° C. and the basic ethanol solution was added slowly with rapid stirring. The reaction exothermed and turned red-black. Once the exotherm resided, the reaction was allowed to warm to rt and stirred an additional 6 h until TLC analysis (Rf=0.60, 25% ethyl acetate:hexanes) showed all starting material had been consumed, at which time the mixture was recooled to 0° C. HCl (12M) was added dropwise until the pH was neutral. The organics were extracted with ethyl acetate (3×30 mL), washed with brine, dried over Na₂SO₄, and concentrated down to yield a crude black oil. The crude product was purified using flash column chromatography on silica gel in a 20% ethyl acetate:hexanes solution as eluant to afford a pure white crystalline solid (6.4 g, 90%). Full spectral data for this compound has been reported (Iyer, S.; Liebeskind, L. S.; J. Am. Chem. Soc. 1987, 109, 2759-2770).

6.1. d 1-(chloromethyl)-2,3,5-trimethoxy-4,6-dimethylbenzene

In a round bottom flask equipped with a stir bar, methoxy-protected hydroquinone (3.2 g, 16.3 mmol) was dissolved in conc. HCl (25 mL) and stirred at room temperature. Paraformaldehyde powder (1 g, 33.3 mmol) was added to the flask along with ZnCl₂ (1 g, 32 mmol). The white, heterogeneous mixture was heated to reflux until all solids were in solution. The reaction was then allowed to cool to room temperature and stirred 3-4 h, until complete according to TLC analysis (Rf=0.60, 25% ether:hexanes). Distilled water was added to the reaction flask and the organics were extracted with ethyl acetate (3×30 mL), washed with brine, dried over Na₂SO₄, and concentrated down to afford a clear, yellow oil. The crude product was purified using flash column chromatography with a solution of 20% ethyl acetate:hexanes to afford the benzylic chloride (3.45 g, 86%) as a white solid.

HRMS Calcd for C₁₂H₁₇O₃: 244.0869. Found: 244.0866. Ms m/z (%): 244(100), 229(6), 201(2), 194(5), 179(21), 166(28), 151(26), 135(7), 123(22), 91(26). IR (KBr) cm⁻¹: 2939, 2831, 1711, 1637, 1466, 1404, 1271, 1196, 1117, 1067, 1002, 964, 910, 731. ¹H NMR (CDCl₃) δ: 4.710 (s, 2H), 3.910 (s, 3H), 3.814 (s, 3H), 3.676 (s, 3H), 2.315 (s, 3H), 2.216 (s, 3H). ¹³C NMR (CDCl₃) δ: 153.3, 149.9, 148.3, 128.0, 126.7, 126.6, 61.5, 60.3, 38.7, 11.6, 9.8.

6.1.e 2-(chloromethyl)-6-methoxy-3,5-dimethylcyclohexa-2,5-diene-1,4-dione 37

In a round bottom flask covered with foil and equipped with a stir bar, CAN (1.1 g, 1.98 mmol) was dissolved in a solution of CH₃CN:H₂O (2:1, 10 mL) and stirred at room temperature. Benzylic chloride (0.15 g, 0.50 mmol) was added to the red-orange solution and stirred at rt for 4 h. Once the oxidation was completed according to TLC (Rf=0.85, 25% ethyl acetate:hexanes), the solution was diluted with distilled water and the organics were extracted with ether (3×10 mL), washed with brine, dried over Na₂SO₄, and concentrated down to a bright yellow solid. The crude solid was purified using flash column chromatography on silica gel with a 10% ethyl acetate:hexanes solution as eluant affording pure chloromethylquinone 37 as a yellow solid (0.43 g, 82%). Care was taken to run the column quickly and limit exposure to light, and the pure product was stored at −78° C. under an inert atmosphere of argon to minimize decomposition.

HRMS Calcd for C₁₀H₁₁O₃Cl: 214.0390. Found: 214.0397. Ms m/z (%): 214(7), 178(100), 171(16), 151(42), 123(23), 107(6), 91(12), 83(13), 77(24), 67(24), 53(34). IR (KBr) cm⁻¹: 3055, 2986, 2947, 2853, 1639, 1616, 1445, 1375, 1249, 1269, 1256, 1198, 1157, 1084, 974, 893, 815, 757, 711, 699. ¹H NMR (CDCl₃) δ: 4.384 (s, 2H), 3.962 (s, 3H), 2.083 (s, 3H), 1.884 (s, 3H). ¹³C NMR (CDCl₃) δ: 187.8, 181.2, 155.3, 144.1, 137.1, 129.1, 61.1, 35.3, 12.4, 9.0.

6.2. Cross Coupling of the Alane 54 (n=9) and Compound 37

Compound 11 was synthesized from the chloromethyl analog 37 and the alane 54 (n=9) following the cross coupling procedures outlined in Example 1. The amounts of reagents were as follows: solanesyl propyne (0.600 g, 0.933 mmol), Cp₂ZrCl₂ (23 mg, 0.07 mmol), DCE (2 mL), H₂O (0.07 μL), NiCl₂(PPh₃)₂ (18 mg, 0.028 mmol), THF (2 mL), nBuLi (13 μL, 0.056 mmol), compound 37 (85 mg, 0.4 mmol). The final product was purified by flash chromatography using silica gel treated with a very small amount of Et₃N (0.25%) and a hexanes:Et₂O gradient solvent system (100% hexanes to 95%:5% hexanes:Et₂O) yielded 194 mg of a red-orange oil (47.0%). TLC:R_f=0.60 (5% Et₂O:hexanes).

HRMS Calcd for C₅₉H₉₀O₃: 846.6855. Found: 846.6890. Ms m/z (%): 849(2), 667(15) 257(1), 135(13), 121(16), 93(22), 81(53), 69(100), 54(22), 43(11). IR (KBr) cm⁻¹: 3053, 2986, 1649, 1612, 1421, 1265, 897, 739, 704. ¹H NMR (CDCl₃) δ: 5.121 (m, 9H), 4.956 (t, J=6.4 Hz, 1H), 3.974 (s, 3H), 3.195 (d, J=6.8 Hz, 2H), 2.008-1.944 (m, 42H), 1.751 (s, 3H), 1.687 (s, 3H), 1.605 (m, 24H), 1.584 (s, 3H). ¹³C NMR (CDCl₃) δ: 188.9, 183.4, 155.6, 141.9, 140.7, 137.6, 135.4, 135.1, 131.4, 128.7, 124.6, 124.4, 124.3, 124.0, 119.3, 61.0, 39.9, 26.9, 26.7, 25.9, 25.3, 17.9, 16.5, 16.2, 12.5, 9.0. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1177, −1416. Regioisomer ratio: 96:4, 2% hydroquinone impurity.

Example 7

Synthesis of Compound 11a

Compound 11a was synthesized using the procedure outlined in Example 6, with the difference that the alane 54 (n=9) in the cross coupling reaction is replaced with a shorter carboaluminated species 54, wherein n is 3.

HRMS Calcd for C₂₉H₄₂O₃: 438.3132. Found: 438.3134. Ms m/z (%): 438(16), 302(5), 257(6), 234(17), 219(32), 181(31), 135 (10), 81(35), 69(100). ¹H NMR (CDCl₃) δ: 5.074 (m, 3H), 4.950 (t, J=7 Hz, 1H), 3.967 (s, 3H), 3.188 (d, J=7.2 Hz, 2H), 2.066-1.937 (m, 15H), 1.744 (s, 3H), 1.676 (s, 3H), 1.596 (s, 3H), 1.580 (m, 9H). ¹³C NMR (CDCl₃) δ: 188.9, 183.4, 155.6, 141.9, 140.7, 137.6, 135.4, 135.1, 131.5, 128.7, 124.6, 124.3, 124.1, 119.3, 61.0, 39.9, 26.9, 26.8, 26.7, 25.9, 25.3, 17.9, 16.5, 16.2, 12.5, 9.0.

Example 8

Synthesis of Compound 3

8.1, Synthesis of 2,4-dimethoxy-3-methylbenzaldehyde

The title compound was prepared according to the procedure outlined in Example 4.1.b [synthesis of 2,4-dimethoxy-3,6-dimethylbenzaldehye]. The following reagents were used: 2,6-dimethoxytoluene (24.0 g, 158.0 mmol), POCl₃ (29.4 mL, 48.5 g, 316.0 mmol), DMF (24.5 mL, 23.1 g, 316.0 mmol). The reaction was worked up with sat. NaHCO₃, extracted with ethyl acetate (3×100 mL), rinsed with brine, dried over anhydrous Na₂SO₄, and concentrated in vacuo. The crude yellow oil was purified by flash column chromatography on silica gel in 20% ethyl acetate:hexanes to afford a white, crystalline solid (27.3 g, 96%, R_f=0.45 in 25% ethyl acetate:hexanes). Full spectral data for this compound has been reported (Harrowven, D. C.; Tyte, M. J. Tet. Lett. 2001, 42, 8709-8711).

8.2. Synthesis of 5-bromo-2,4-dimethoxy-3-methylbenzaldehyde

In a 250 mL round bottom flask equipped with a stir bar, 2,4-dimethoxy-3-methylbenzaldehyde (24.7 g, 137.2 mmol) was dissolved in acetic acid (150 mL). Bromine (9.13 mL, 28.5 g, 178.32 mmol) was added dropwise and the reaction was stirred at rt for 12 h. Once the reaction had gone to completion according to TLC, excess bromine was quenched using saturated, aqueous thiosulfate (20 mL). The organics were extracted in ethyl acetate (3×100 mL), rinsed with brine, dried over anhydrous Na₂SO₄, and concentrated in vacuo to afford a pale yellow solid. The crude product was then purified by flash column chromatography on silica gel using a gradient solvent system of 0-20% ethyl acetate:hexanes to afford a pure white solid (32.52 g, 92%, R_f=0.6, 40% ethyl acetate:hexanes).

HRMS Calcd for C₁₀H₁₁O₃Br: 257.9879. Found: 257.9878. Ms m/z (%): 258(100), 243(47), 227(22), 212(31), 162(97), 91(25), 77(55), 51(45). IR (KBr) cm⁻¹: 3003, 2941, 2864, 1686, 1579, 1454, 1383, 1265, 1096, 999, 892, 815, 738. ¹H NMR (CDCl₃) δ: 10.174 (s, 1H), 7.842 (s, 1H), 3.845 (s, 3H), 3.822 (s, 3H), 2.259 (s, 3H). ¹³C NMR (CDCl₃) δ: 188.22, 162.36, 161.47, 130.32, 128.13, 126.78, 113.63, 63.50, 60.56, 9.89.

8.3, Synthesis of 5-bromo-2-hydroxy-4-methoxy-3-methylbenzaldehyde

In a 250 mL round bottom flask equipped with a stir bar, 5-bromo-2,4-dimethoxy-3-methylbenzaldehyde (5.28 g, 20.49 mmol) was dissolved in CH₂Cl₂ (50 mL) and cooled to 0° C. To this was added BCl₃ (24.59 mL, 1 M in hexanes, 24.59 mmol). The reaction was allowed to warm to rt and stirred for 5 h. Once the reaction had gone to completion according to TLC, the contents of the flask were diluted with ether and poured over ice water. The organics were extracted in ethyl acetate (3×50 mL), rinsed with brine, dried over anhydrous Na₂SO₄, and concentrated in vacuo to an off-white solid. The crude product was then purified by flash column chromatography on silica gel using a gradient solvent system of 0-30% ethyl acetate:hexanes to afford a pure white solid (4.6 g, 92%, R_f=0.6, 30% ethyl acetate:hexanes).

EMS Calcd for C₉H₉O₃Br: 243.9743. Found: 243.9735. Ms m/z (%): 244(100), 229(17), 228(19), 216(20), 214(20), 167(15), 149(60), 94(32), 65(47). IR (KBr) cm⁻¹: 3292, 3055, 2966, 2943, 2852, 1649, 1612, 1570, 1414, 1375, 1308, 1265, 1244, 1107, 1024, 993, 797, 739. ¹H NMR (CDCl₃) δ: 11.38 (s, 1H), 9.76 (s, 1H), 7.61 (s, 1H), 3.87 (s, 3H), 2.24 (s, 3H). ¹³C NMR (CDCl₃) δ: 194.9, 162.1, 161.2, 134.9, 122.3, 118.3, 107.5, 60.9, 9.2.

8.4. Synthesis of 4-bromo-6-(hydroxymethyl)-3-methoxy-2-methylphenol

In a round bottom flask equipped with a stir bar, 5-bromo-2-hydroxy-4-methoxy-3-methylbenzaldehyde (0.24 g, 0.98 mmol) was dissolved in THF (10 mL). The light yellow solution was cooled to 0° C. and NaBH₄ (37.24 mg, 0.98 mmol) was added slowly. After 6-8 h at rt, the reaction had gone to completion and the clear solution was cooled to 0° C. Aq. HCl (1 M) was added dropwise until the solution pH=2. The organics were extracted with CHCl₃ (3×20 mL), dried over anhydrous Na₂SO₄, and concentrated in vacuo to afford a clear oil (0.24 g, 95%, R_f=0.2, 30% ethyl acetate:hexanes) that was pure according to TLC. The crude was taken directly on to the next step without further purification. It should be noted that CHCl₃ has been used specifically to minimize the amount of reduction byproducts carried into the next step.

8.5. Synthesis of 5-(hydroxymethyl)-2-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione

In a round bottom flask equipped with a stir bar, freshly prepared Fremy's salt (0.67 g, 2.5 mmol) was dissolved in a 1:1 solution of acetone:sodium phosphate buffer (pH=5.8) and stirred. The flask was covered with foil to avoid exposure to light. Crude 4-bromo-6-(hydroxymethyl)-3-methoxy-2-methylphenol (0.24 g, 0.98 mmol) was then dissolved in acetone and added to the stirring solution of Fremy's salt. Once the reaction was complete according to TLC, the hydroxymethyl quinone was extracted in CHCl₃ (3×50 mL) and the combined organics were dried over anhydrous Na₂SO₄, concentrated in vacuo to a dark red oil, and put on high vacuum. The crude product (R_f=0.5, 40% ethyl acetate:hexanes) was then dried azeotropically with benzene to remove any residual water before being carried on to the next step. It should be noted that the phosphate buffer must contain the sodium salt, as the potassium salt precipitates out during the reaction, causing rapid polymerization of the substrate. Also, failure to adequately dry the substrate at this stage results in much lower yields of the subsequent chlorination reaction due to the generation of HCl in situ.

8.6. Synthesis of 5-(chloromethyl)-2-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione (33a)

In a dry, argon-flushed round bottom flask equipped with a stir bar and covered with foil, freshly distilled DMF (0.23 mL, 0.215 g, 2.94 mmol) was stirred and cooled to 0° C. Freshly distilled PCl₃ (0.26 mL, 0.40 g, 2.94 mmol) was then added slowly to the flask of DMF. The solution was stirred 1 h, forming a white, crystalline salt (Vilsmeier's salt), Crude 5-(hydroxymethyl)-2-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione was then dissolved in freshly distilled THF and added to the flask containing the salt. After 4-6 h of stirring at rt, the reaction was complete. Ether (15 mL) was added and the mixture was poured over a filter of silica gel to separate the organics from excess reagent and polymeric material. The resulting bright yellow filtrate was concentrated in vacuo to a dark, orange-red oil, Care was taken to avoid exposure to light, water, or heat, as this would result in polymerization. The product was immediately purified by flash column chromatography on silica gel in a gradient solvent system of 0-15% ether:hexanes to afford a pure yellow solid (0.076 g, 38.7%, R_f=0.85, 30% ethyl acetate:hexanes). It should be noted that if, during the generation of the Vilsmeier salt, no solid formed or the solid had a yellow tint, the flask was discarded. The yellow color and failure to crystallize were generally indications that excess HCl resulting from a wet reagent was present. Under such conditions, the amount of polymeric byproducts was substantially increased.

HRMS Calcd for C₉H₉O₃Cl: 200.0232. Found: 200.0240. Ms m/z (%): 200(44), 165(37), 164(42), 137(31), 134(100), 109(43), 83(59), 67(94), 55(37). IR (KBr) cm⁻¹: 2955, 2926, 2855, 1653, 1608, 1447, 1377, 1321, 1290, 1209, 1146, 739. ¹H NMR (CDCl₃) δ: 6.725 (s, 1H), 4.401 (s, 2H), 4.038 (s, 3H), 1.948 (s, 3H). ¹³C NMR (CDCl₃) δ: 186.66, 183.28, 155.94, 143.63, 132.11, 128.71, 61.15, 39.58, 8.92.

8.7. Synthesis of Compound 3

The title compound was prepared from the chloromethylene analog 33a and 54 (n=9) according to the procedures outlined in Example 1. The following reagents were used in the specified amounts: 5-(chloromethyl)-2-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione 33a (84.0 mg, 0.42 mmol), solanesyl propyne (0.5 g, 0.765 mmol), Cp₂ZrCl₂ (0.011 g, 0.038 mmol), AlMe₃ (0.57 mL, 2 M solution in toluene, 1.15 mmol), MAO (0.02 mL, 10% w/w solution in toluene, 0.038 mmol), NiCl₂(PPh₃)₂ (24.84 mg, 0.038 mmol), THF (2 mL), nBuLi (0.03 mL, 2.5 M solution in hexanes, 0.076 mmol), CAN (0.23 g, 0.420 mmol), CH₃CN:H₂O (10:1, 20 mL). The resulting oxidized final product was purified by flash column chromatography on silica gel in a gradient solvent system of 0-10% ether:petrol ether to afford a pure orange-red oil (99.0 mg, 28% (3 steps), R_f=0.80, 10% ether:hexanes).

HRMS Calcd for C₅₈H₈₈O₃Na: 855.6638. Found: 855.6625. Ms m/z (counts): 858(12), 857(35), 856(57), 836(25), 835(80), 437(83), 413(98), 393(151), 381(114). IR (KBr) cm¹, 2963, 2920, 2851, 1649, 1607, 1448, 1381, 1321, 1209, 1144. ¹H NMR (CDCl₃) δ: 6.347 (s, 1H), 5.139-5.107 (m, 10H), 4.012 (s, 3H), 3.122 (d, J=7.2 Hz, 2H), 2.105-1.951 (m, 39H), 1.688 (s, 6H), 1.686-1.607 (m, 27H). ¹³C NMR (CDCl₃) δ: 188.53, 184.04, 155.63, 148.52, 140.04, 135.61, 135.09, 131.42, 130.67, 128.98, 124.57, 124.42, 123.95, 118.13, 61.02, 39.93, 27.60, 26.86, 26.62, 25.91, 17.88, 16.33, 16.21, 9.07. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1091, −1406. Regioisomer ratio: 90:10, 7% hydroquinone impurity.

Example 9

Synthesis of Compound 15

9.1. Synthesis of 2-ethyl-1,3-dimethoxy-5-methylbenzene

The title compound was prepared according to the procedure outlined in Example 4.1.a (compound 9). The following reagents were used in the specified amounts: trimethoxytoluene (5.0 g, 27.5 mmol), potassium (3.2 g, 82.4 mmol), ethyl iodide (2.7 mL, 3.9 g, 35.8 mmol), THF (50 mL). The crude red-brown oil was purified by flash column chromatography on silica gel in a gradient solvent system of 0-15% ethyl acetate:hexanes to afford a pure, clear oil (3.4 g, 69%, R_f=0.9, 14% ethyl acetate:hexanes). Full spectral data for this compound has been reported previously (Azzena, U.; Denurra, T.; Melloni, G.; Piroddi, A. M.; J. Org. Chem. 1990, 55, 5386-5390).

9.2. Synthesis of 3-ethyl-2,4-dimethoxy-6-methylbenzaldehyde

The title compound was prepared according to the procedure outlined in Example 8.1. (synthesis of 2,4-dimethoxy-3-methylbenzaldehyde). The following reagents were used in the specified amounts: 2-ethyl-1,3-dimethoxy-5-methylbenzene (5.0 g, 27.8 mmol), POCl₃ (5.2 mL, 8.5 g, 55.6 mmol), DMF (8.6 mL, 8.1 g, 111.0 mmol). The resulting brown oil was purified by flash column chromatography on silica gel in a gradient solvent system of 5%-25% ethyl acetate:hexanes to afford a pure, yellow oil (4.51 g, 78%, R_f=0.65, 14% ethyl acetate:hexanes).

HRMS Calcd for C₁₂H₁₆O₃Na: 231.1002. Found: 231.0991. Ms m/z (counts): 231(207), 210(20), 209(133), 17918), 130(12), 102(10). IR (KBr) cm⁻¹: 2964, 2873, 1682, 1595, 1555, 1454, 1379, 1323, 1296, 1218, 1128, 1089, 1058, 1014, 918, 792, 575, 521. ¹H NMR (CDCl₃) δ: 10.394 (s, 1H), 6.506 (s, 1H), 3.885 (s, 3H), 3.842 (s, 3H), 2.645 (q, J=7.2 Hz, 2H), 2.598 (s, 3H), 1.143 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 191.55, 164.08, 162.65, 141.84, 123.98, 121.13, 110.12, 64.55, 55.84, 22.18, 16.72, 14.36.

9.3. Synthesis of 3-ethyl-2-hydroxy-4-methoxy-6-methylbenzaldehyde

The title compound was prepared according to the procedure outlined in Example 8.3 (synthesis of 5-bromo-2-hydroxy-4-methoxy-3-methylbenzaldehyde). The following reagents were used in the specified amounts: 3-ethyl-2,4-dimethoxy-6-methylbenzaldehyde (4.61 g, 22.16 mmol), BCl₃ (44.32 mL, 1 M in hexanes, 6.78 g, 44.32 mmol), CH₂Cl₂ (100 mL). The resulting white solid was purified by flash column chromatography on silica gel in a gradient solvent system of 5%-20% ethyl acetate:hexanes to afford yellow, needle-shaped crystals (3.93 g, 91%, R_f=0.75 in 20% ethyl acetate:hexanes).

HRMS Calcd for C₁₁H₁₄O₃: 194.0946. Found: 194.0943. Ms m/z (%): 194(62), 179(100), 164(12), 149(15), 77(11). IR (KBr) cm⁻¹: 3488, 2970, 2876, 1624, 1504, 1464, 1412, 1358, 1294, 1225, 1144, 1084, 1020, 914, 746, 649. ¹H NMR (CDCl₃) δ: 12.385 (s, 1H), 10.122 (s, 1H), 6.279 (s, 1H), 3.889 (s, 3H), 2.620 (q, J=7.2 Hz, 2H), 2.560 (s, 3H), 1.081 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 193.45, 164.12, 162.81, 142.00, 117.67, 113.73, 105.46, 55.89, 18.69, 15.51, 13.43.

9.4. Synthesis of 2-ethyl-6(hydroxylmethyl)-3-methoxy-5-methylphenol

The title compound was prepared according to the procedure outlined in Example 8.4. (synthesis of 4-bromo-6-(hydroxymethyl)-3-methoxy-2-methylphenol). The following reagents were used in the specified amounts: 3-ethyl-2-hydroxy-4-methoxy-6-methylbenzaldehyde (3.93 g, 20.26 mmol), NaBH₄ (0.77 g, 20.26 mmol), THF (100 mL). The resulting clear oil (3.92 g, 95%, R_f=0.55 in 40% ethyl acetate:hexanes) was taken on to the next step crude.

9.5. Synthesis of 2-ethyl-6-(hydroxymethyl)-3-methoxy-5-methylcyclohexa-2,5-diene-1,4-dione

The title compound was prepared according to the procedure outlined in Example 4.1.e [synthesis of 2-(hydroxymethyl)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione]. The following reagents were used in the specified amounts: 2-ethyl-6-(hydroxylmethyl)-3-methoxy-5-methylphenol (3.9 g, 20.0 mmol), Fremy's salt (21.7 g, 81.04 mmol), acetone (200 mL), pH 5.8 phosphate buffer (200 mL). The resulting bright red-orange solid (4.2 g impure material, R_f=0.45, 40% ethyl acetate, hexanes) was azeotropically dried with benzene and taken on to the next step crude.

9.6. Synthesis of 2-(chloromethyl)-6-ethyl-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione (36a)

The title compound was prepared according to the procedure outlined in Example 4.1.f [synthesis of 2-(chloromethoxy)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione]. The following reagents were used in the specified amounts: 2-ethyl-6-(hydroxymethyl)-3-methoxy-5-methylcyclohexa-2,5-diene-1,4-dione (4.2 g impure crude material), PCl₃ (5.3 mL, 8.4 g, 60.8 mmol), DMF (4.7 mL, 4.4 g, 60.8 mmol), THF (40 mL). The resulting red-orange crude oil was purified by flash column chromatography on silica gel in a gradient solvent system of 0%-10% ethyl acetate:hexanes to afford a bright orange oil (1.93 g, 42% (three steps), R_f=0.65, 10% ethyl acetate:hexanes).

HRMS Calcd for C₁₁H₁₃O₃Cl: 228.0542. Found: 228.0553. Ms m/z (%): 228(42), 213(18), 193(84), 192(63), 174(68), 119(20), 91(37), 81(40), 53(100). IR (KBr) cm⁻¹: 2939, 2876, 1653, 1612, 1458, 1447, 1381, 1353, 1323, 1252, 1146, 1055, 995, 866, 762. ¹H NMR (CDCl₃) δ: 4.450 (s, 2H), 4.000 (s, 3H), 2.481 (q, J=7.2 Hz, 2H), 2.143 (s, 3H), 1.049 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 185.47, 183.89, 155.73, 142.48, 138.65, 134.48, 61.30, 35.73, 17.02, 13.62, 12.02.

9.7. Synthesis of Compound 15

The title compound was prepared from 36a and 54 (n=9) according to the procedures outlined in Example 1. The following reagents were used in the specified amounts: 2-(chloromethyl)-6-ethyl-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione (0.174 g, 0.76 mmol), solanesylpropyne (0.5 g, 0.765 mmol), Cp₂ZrCl₂ (0.011 g, 0.038 mmol), AlMe₃ (0.58 mL, 2 M solution in toluene, 0.083 g, 1.15 mmol), MAO (0.02 ml, 0.0029 g, 0.038 mmol), NiCl₂(PPh₃)₂ (0.025 g, 0.038 mmol), THF (2 mL), nBuLi (0.03 mL, 2.5 M solution in hexanes, 0.076 mmol), CAN (1.0 g, 1.9 mmol), CH₃CN:H₂O (10:1, 40 mL total). The oxidized final product was purified by flash column chromatography on silica gel in a gradient solvent system of 0-10% ethyl acetate:hexanes to afford a pure orange-red oil (0.209 g, 32% (three steps), R_f=0.7, 10% ethyl acetate:hexanes).

HRMS Calcd for C₆₀H₉₂O₃: 860.7065. Found: 860.7046. Ms m/z(%): 863(18), 861(13), 233(91), 195(40), 135(19), 121(23), 95(29), 69(100), 54(32). IR (KBr) cm⁻¹: 2964, 2922, 2851, 1647, 1610, 1448, 1381, 1350, 1323, 1254, 1146, 1045, 989, 838. ¹H NMR (CDCl₃) δ: 5.138-5.052 (m, 9H), 4.953 (t, J=1.2 Hz, 1H), 3.976 (s, 3H), 3.199 (d, J=7.2 Hz, 2H), 2.460 (q, J=7.2 Hz, 2H), 2.105-1.936 (m, 39H), 1.752 (s, 3H), 1.688 (s, 6H), 1.605-1.582 (m, 24H), 1.404-1.340 (m, 4H), 1.044 (t, J=7.2 Hz, 3H). ¹³C NMR(CDCl₃) δ: 187.62, 184.57, 155.30, 143.51, 138.96, 137.46, 135.40, 135.14, 134.30, 131.45, 124.60, 124.45, 125.36, 124.07, 119.42, 61.20, 39.95, 26.90, 26.72, 25.92, 25.83, 17.90, 17.03, 16.53, 16.23, 13.74, 11.92. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1126, −1374. Regioisomeric ratio: 96:4, 2% hydroquinone impurity.

Example 10

Synthesis of Compound 17

10.1. Synthesis of 2-butyl-1,3-dimethoxy-5-methylbenzene

The title compound was prepared according to the procedure outlined in Example 4-1.a [synthesis of 1,3-dimethoxy-2,5-dimethylbenzene]. The following reagents were used in the specified amounts: trimethoxytoluene (5.0 g, 27.5 mmol), potassium (3.22 g, 82.42 mmol), n-butyl bromide (3.86 mL, 4.9 g, 35.75 mmol), THF (50 mL). The resulting red-brown oil was vacuum distilled to afford a pure, clear oil (4.4 g, 77%, R_f=0.9, 14% ethyl acetate:hexanes).

HRMS Calcd for C₁₃H₂₀O₂: 208.1455. Found: 208.1450. Ms m/z(%): 208(18), 165(100), 105(24), 91(6), 79(5), 43(8) IR (KBr) cm⁻¹: 2995, 2955, 2858, 2835, 1608, 1587, 1456, 1416, 1313, 1247, 1205, 1140, 1076, 970, 812. ¹H NMR (CDCl₃) δ: 6.401 (s, 2H), 3.826 (s, 6H), 2.633 (t, J=7.2 Hz, 2H), 2.370 (s, 3H), 1.497-1.353 (m, 4H), 0.952 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 158.28, 136.53, 116.72, 104.77, 55.83, 31.94, 23.10, 22.68, 22.18, 14.30.

10.2. Synthesis of 3-butyl-2,4-dimethoxy-6-methylbenzaldehyde

The title compound was prepared according to the procedure outlined in Example 4.1.b [synthesis of 2,4-dimethoxy-3,6-dimethylbenzaldehye]. The following reagents were used: 2-butyl-1,3-dimethoxy-5-methylbenzene (0.5 g, 2.4 mmol), POCl₃ (0.45 mL, 0.74 g, 4.8 mmol), DMF (0.37 mL, 0.35 g, 4.8 mmol). The resulting brown oil was purified by flash column chromatography on silica gel in a gradient solvent system of 0-25% ethyl acetate:hexanes to afford a pure, yellow oil (0.42 g, 68%, R_f=0.5, 14% ethyl acetate:hexanes).

HRMS Calcd for C₁₄H₂₀O₃Na: 259.1317. Found: 259.1304. Ms m/z (counts): 259(133), 237(36), 181(10), 133(8). IR (KBr) cm⁻¹: 2957, 2860, 1682, 1596, 1462, 1379, 1323, 1299, 1220, 1207, 1130, 1072, 1016, 838, 789, 577. ¹H NMR (CDCl₃) δ: 10.386 (s, 1H), 6.496 (s, 1H), 3.871 (s, 3H), 3.827 (s, 3H), 2.614-2.576 (m, 5H), 1.529-1.453 (m, 2H), 1.427-1.336 (m, 2H), 0.934 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 191.53, 164.26, 162.70, 141.77, 122.74, 121.07, 110.07, 64.42, 55.81, 32.01, 23.17, 23.12, 22.15, 14.14.

10.3. Synthesis of 3-butyl-2-hydroxy-4-methoxy-6-methylbenzaldehyde

The title compound was prepared according to the procedure outlined in Example 8.3. [synthesis of 5-bromo-2-hydroxy-4-methoxy-3-methylbenzaldehyde]. The following reagents were used in the specified amounts: 3-butyl-2,4-dimethoxy-6-methylbenzaldehyde (3.14 g, 13.3 mmol), BCl₃ (19.95 mL, 1 M in hexanes, 3.05 g, 19.95 mmol), CH₂Cl₂ (40 mL). The resulting yellow solid was purified by flash column chromatography on silica gel in a gradient solvent system of 0%-15% ethyl acetate:hexanes to afford yellow, needle-shaped crystals (3.00 g, 95%, R_f=0.8, 20% ethyl acetate:hexanes).

HRMS Calcd for C₁₃H₁₈O₃: 222.1262. Found: 222.1256. Ms m/z (%): 222(25), 193(10), 179(100), 149(14), 91(7). IR (KBr) cm⁻¹: 3417, 2957, 2860, 1628, 1573, 1498, 1463, 1412, 1360, 1294, 1256, 1225, 1144, 1020, 822, 733. ¹H NMR (CDCl₃) δ: 12.389 (s, 1H), 10.120 (s, 1H), 6.276 (s, 1H), 3.882 (s, 3H), 2.594 (t, J=7.2 Hz, 2H) 2.560 (s, 3H), 1.499-1.307 (m, 4H), 0.921 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 193.43, 164.30, 163.03, 141.97, 116.43, 113.69, 105.43, 55.87, 31.16, 22.98, 21.86, 18.70, 14.24.

10.4. Synthesis of 2-butyl-6(hydroxymethyl)-3-methoxy-5-methylphenol

The title compound was prepared according to the procedure outlined in Example 8.4. [synthesis of 4-bromo-6-(hydroxymethyl)-3-methoxy-2-methylphenol]. The following reagents were used in the specified amounts: 3-butyl-2-hydroxy-4-methoxy-6-methylbenzaldehyde (0.85 g, 3.83 mmol), NaBH₄ (0.142 g, 3.83 mmol), THF (20 mL). The resulting clear oil (0.85 g, 98%, R_f=0.55, 43% ethyl acetate:hexanes) was taken on to the next step without further purification.

10.5. Synthesis of 2-butyl-6-(hydroxymethyl)-3-methoxy-5-methylcyclohexa-2,5-diene-1,4-dione

The title compound was prepared according to the procedure outlined in Example 4.1.e [synthesis of 2-(hydroxymethyl)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione]. The following reagents were used in the specified amounts: 2-butyl-6-(hydroxymethyl)-3-methoxy-5-methylphenol (0.85 g, 3.8 mmol), Fremy's salt (4.07 g, 15.18 mmol), acetone (20 mL), pH 5.8 phosphate buffer (20 mL), The resulting dark red solid (1.02 g (impure), R_f=0.45, 43% ethyl acetate:hexanes) was azeotropically dried with benzene and taken on to the next step crude.

10.6. Synthesis of 2-butyl-6(chloromethyl)-3-methoxy-5-methylcyclohexa-2,5-diene-1,4-dione (36b)

The title compound was prepared according to the procedure outlined in Example 4.1.f [synthesis of 2-(chloromethoxy)-5-methoxy-3,6-dimethylcyclohexa-2,5-diene-1,4-dione 36]. The following reagents were used in the specified amounts: 2-butyl-6-(hydroxymethyl)-3-methoxy-5-methylcyclohexa-2,5-diene-1,4-dione (1.02 g (impure)), PCl₃ (0.99 mL, 1.56 g, 11.4 mmol), DMF (0.89 mL, 0.83 g, 11.4 mmol), THF (25 mL). The resulting dark red oil was purified by flash column chromatography on silica gel in a gradient solvent system of 0-10% ethyl acetate:hexanes to afford a red-orange oil (0.33 g, 34% (three steps), R_f=0.8, 29% ethyl acetate:hexanes).

HRMS Calcd for C₁₃H₁₇O₃Cl: 256.0878. Found: 256.0866. Ms m/z(%): 256(21), 222(16), 214(31), 205(48), 191(35), 185(22), 178(57), 150(31), 107(20), 91(47), 77(44), 53(100). IR (KBr) cm⁻¹: 2957, 2932, 1653, 1610, 1448, 1279, 1256, 1219, 1146, 1070, 762. ¹H NMR (CDCl₃) δ: 4.451 (s, 2H), 3.997 (s, 3H), 2.464 (t, J=7.2 Hz, 2H), 2.148 (s, 3H), 1.422-1.339 (m, 4H), 0.919 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 185.63, 183.82, 155.94, 142.46, 138.61, 133.32, 61.23, 35.73, 31.23, 23.33, 23.06, 14.05, 12.00.

10.6. Synthesis of Compound 17

The title compound was prepared from 36b and 54 (n=9) according to the procedures outlined in Example 1. The following reagents were used in the specified amounts: 2-(chloromethyl)-6-butyl-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione (0.100 g, 0.39 mmol), solanesyl propyne (0.5 g, 0.765 mmol), Cp₂ZrCl₂ (0.011 g, 0.038 mmol), AlMe₃ (0.58 mL, 2 M solution in toluene, 0.083 g, 1.15 mmol), MAO (0.02 mL, 0.0029 g, 0.038 mmol), NiCl₂(PPh₃)₂ (24.8 mg, 0.038 mmol), THF (2 mL), nBuLi (0.03 mL, 2.5 M solution in hexanes, 0.076 mmol), CAN (0.21 g, 0.39 mmol), CH₃CN:H₂O (10:1, 20 mL total). The resulting oxidized final product was purified by flash column chromatography on silica gel in a gradient solvent system of 0-10% ethyl acetate:hexanes to afford a pure orange-red oil (0.17 g, 49% (three steps), R_f=0.8, 10% ethyl acetate:hexanes).

HRMS Calcd for C₆₂H₉₆O₃: 888.7399. Found: 888.7359. Ms m/z (%): 891(100), 669(35), 531(12), 327(28), 150(11), 122(23), 81(75), 69(100), 54(25). IR (KBr) cm⁻¹: 2962, 2922, 2853, 1651, 1610, 1447, 1381, 1263, 1148, 1103, 1006, 839, 741. ¹H NMR (CDCl₃) δ: 5.139-5.070 (m, 9H), 4.951 (t, J=1.2 Hz, 1H), 3.980 (s, 3H), 3.196 (d, J=7.2 Hz, 2H), 2.437 (t, J=7.2 Hz, 2H), 2.106-1.938 (m, 42H), 1.736 (s, 3H), 1.689 (s, 3H), 1.607-1.584 (m, 24H), 1.371-1.340 (m, 4H), 0.917 (t, J=7.2 Hz, 3H). ¹³C NMR (CDCl₃) δ: 187.84, 184.54, 155.54, 143.50, 138.97, 137.47, 135.42, 135.16, 133.14, 131.48, 124.60, 124.45, 124.08, 119.43, 61.16, 39.96, 32.21, 31.39, 29.93, 26.91, 26.74, 25.93, 23.66, 23.40, 23.13, 17.91, 16.56, 16.24, 14.13, 11.95. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1138, −1326. Regioisomeric ratio: 94:6, 3% hydroquinone impurity.

Example 11

Synthesis of Compound 23 (Z¹=H)

11.1. Synthesis of 2-(chloromethyl)-3-methylnaphthalene-1,4-dione (35a)

The title compound was prepared according to the procedures outlined in Example 3.1.b (preparation of 1-(chloromethyl)-2,4-,dimethoxy-3,4,6-trimethylbenzene) The following reagents were used in the specified amounts: naphthoquinone (5.0 g, 29.0 mmol), ZnCl₂ (3.94 g, 29.0 mmol), concentrated HCl (10 mL), paraformaldehyde (1.98 g, 58.0 mmol). Flash column chromatography on silica gel in 5% ether:hexanes afforded the product as a yellow solid (4.9 g, 77%, R_f=0.8, 10% ethyl acetate:hexanes). Full spectral data for this compound has been reported (Lipshutz, B. H.; Kim, S-k.; Mollard, P.; Stevens, K. L. Tetrahedron, 1998, 54, 1241-1253).

11.1. Synthesis of Compound 23

The title compound was prepared from 35a and 54 (n=9) according to the procedures outlined in Example 1. The following reagents were used in the specified amounts: 2-(chloromethyl)naphthalene (0.18 g, 0.8 mmol), solanesyl propyne (0.654 g, 1.0 mmol), Cp₂ZrCl₂ (0.011 g, 0.038 mmol), AlMe₃ (0.75 mL, 2 M solution in toluene, 1.5 mmol), MAO (0.064 mL, 0.073 g, 0.10 mmol), NiCl₂(PPh₃)₂ (26.2 mg, 0.04 mmol), THF (2 mL), nBuLi (30 μL, 2.5 M solution in hexanes, 0.08 mmol, 30 μL). The final product was purified by flash column chromatography on silica gel in a gradient solvent system of 0-10% ether:pet. ether to afford a pure yellow solid (0.53 g, 78% (two steps), R_f=0.80, 2% ether:hexanes).

HRMS Calcd for C₆₁H₈₈O₂: 852.6820. Found: 852.6843. Ms m/z (%): 852(3), 224(11), 203(6), 187(12), 161(10), 137(15), 135(26), 120(15), 109(23), 69(100), 55(32). IR (KBr) cm⁻¹: 2964, 2920, 2853, 1661, 1447, 1381, 1296, 910, 735. ¹H NMR (CDCl₃) δ: 8.100-8.072 (m, 2H), 7.699-7.676 (m, 2H), 5.127-5.017 (m, 10H), 3.382 (d, J=7.2 Hz, 2H), 2.200 (s, 3H), 2.075-1.933 (m, 36H), 1.809 (s, 3H), 1.690 (s, 3H), 1.610-1.539 (m, 27H). ¹³C NMR (CDCl₃) δ: 185.60, 184.66, 146.30, 143.50, 137.72, 135.39, 135.09, 133.50, 133.44, 132.31, 131.41, 126.49, 126.37, 124.59, 124.44, 124.32, 124.02, 119.26, 39.92, 26.88, 26.67, 26.19, 25.91, 17.88, 16.62, 16.23, 12.87. E_pc values (mV) vs. Ag/AgNO₃ reference electrode: −1435. Regioisomer ratio: 92:8, 1% hydroquinone impurity.

Example 12

Determination of Reduction Potentials for Selected Ubiquinones

The redox chemistry of a variety of purified ubiquinones of the invention was examined using cyclic voltametry (CV). Methods for the determination of reduction potentials are known in the art and are, for example, described in A. J. Fry, Synthetic Organic Electrochemistry, 2^nd Ed., Wiley-Interscience, New York, 1989.

12.1 Results

The resulting redox data (including those for CoQ₁₀) are listed in the order of increasing first-wave potentials (E_pc1) in Table 1, below. The abbreviation E_pc1 and E_pc2 are used to represent the values of the first and second cathodic peak potentials, respectively. The peak potentials correspond to the first and second reduction wave minima in the recorded CV graphs (see e.g., FIG. 1).

All tested analogs, except for 7 and 23, exhibited two distinct waves representative of a first (Q/Q) and presumed second (Q/Q⁻²) electron transfer. The value of the second peak potential is, typically, an approximation. Chemical side reactions coupled to the transient species generated in the first reduction may contribute to the shape of the wave, and thus the peak potential. CV scans of both 7 and 23 contain a single wave, the intensity of which suggests that second electron transfer occurs either simultaneously with the first, or too rapidly to observe a discernable second wave under these conditions. Representative first and second reduction waves for analogs 1 and 23, as well as for CoQ₁₀, are illustrated in FIG. 1, which represents an expanded portion of the recorded CV graph.

TABLE 1
First- and second wave potentials for selected ubiquinones
[Epc(V) vs. Ag/AgNO3 in DMF]
Compound	Q/Q*−	Q*−/Q−2
No.	(Epc1)	(Epc2)
1	−1.04	−1.35
3	−1.09	−1.41
CoQ10	−1.11	−1.42
15	−1.13	−1.37
17	−1.14	−1.33
11	−1.18	−1.42
2	−1.21	−1.36
9	−1.22	−1.47
7	−1.30	not observed*
23	−1.44	not observed*
*CV scans of both 7 and 23 contain a single wave, the intensity of which suggests that second electron transfer occurs either simultaneously with the first, or too rapidly to observe a discernable second wave under these conditions.

12.2 Effect of Substitution Pattern on Reduction Potential

The most remarkable feature in the reduction potentials of known benzoquinones, and the most relevant to CoQ₁₀ reduction, is the steric effect for the 2,3-dimethoxy and 2-methoxy-3-methyl derivatives. The inventors have discovered that current first reduction potential data are consistent with those found for simple substituted benzoquinones with methyl and methoxy substituents (see e.g., R. C. Prince, L. Dutton, J. M. Bruce, FEBS Lett. 1983, 160(1,2), 273-276, and references therein) and that reduction potentials for the ubiquinone analogs described herein can be approximated from additive substituent effects.

Attachment of a methyl group onto the benzoquinone or naphthoquinone ring makes the first reduction potential less favorable (by ca. 0.08 V), while a methoxy group has a similar effect (0.11 V). On the other hand, fission of a benzene ring (in a naphthoquinone) makes the first reduction more favorable (ca. 0.18 V). Replacement of a methyl group with a prenyl group also makes the first reduction slightly more favorable (0.01-0.04 V).

When multiple substituents are present, these effects are closely additive, except in the 2,3-dimethoxy pattern found in CoQ₁₀, as well as in simpler 2-methoxy-3-methyl derivatives, where steric interactions substantially diminish the substituent effect on first reduction potential. For 2,3-dimethoxy cases, reduction potential differences are smaller by 0.16 V than expected. Similar data are seen for 2-methoxy-3-methyl derivatives (0.12 V; cf. Table 1). These additives apply reasonably well to the CoQ₁₀ derivatives in Table 1. The origin of the electronic effects of the methoxy group, and how steric effects alter these, can be defined with the aid of modern quantum calculations.

DFT calculations on planar and non-planar conformers of 2-methoxybenzoquinone in its neutral, radical-anion, and dianion forms show that neutral benzoquinone has a strong preference for a coplanar methoxy group. Twisting to 90° raises the free energy by 5.6 kcal mol⁻¹, suggesting that vinylogous ester resonance is optimal when the methoxy group is coplanar. In the radical anion, however, MeO prefers to rotate 54.5° out of plane (syn to the C═O), presumably to minimize lone-pair repulsion within the charged species. The 2,3-dimethoxybenzoquinone derivative (Table 2), is forced by steric effects to twist the two methoxy groups by 9.2 and 62.3°, respectively, out of the plane of the ring. These are both twisted by 62.6° (syn with C₂ symmetry) in the radical anion. Similarly, in y and z (Table 2), they prefer non-planar geometries. Since the geometries of the methoxy groups in neutral benzoquinones are far from their preferred planar geometries, these derivatives are likely to be substantially destabilized by loss of resonance. However, these three radical anions apparently suffer virtually no energetic losses due to steric repulsion, since the radical anion of 2-methoxybenzoquinone already prefers to have the methoxy group twisted out of plane. The preferred dihedral angle in each of the three radical anions is only slightly larger (by about 10°) than the ideal angle in the 2-methoxybenzoquinone radical anion.

TABLE 2
DFT-calculated geometries and dihedral angles of
benzoquinones x, y, and z.

To quantitatively test this explanation as to the impact of steric effects on reduction potentials, the energies of 2-methoxybenzoquinones have been calculated, with the methoxy groups distorted to the 9.2 and 62.3° dihedral angles imposed in the 2,3-dimethoxybenzoquinone. Their electronic energies differ by 0.15 and 4.02 kcal mol⁻¹, respectively, or 4.17 kcal mol⁻¹ (0.18 V) representing the total predicted steric effect on resonance energy. This matches the observed 0.16 V steric effect. A similar analysis of 2-methyl-3-methoxybenzoquinone, twisted to 18.8°, predicts a smaller steric effect of 3.2 kcal mol⁻¹ (0.14 V), which again compares favorably with that observed (0.12 V). Thus, the substitution pattern found in natural CoQ₁₀ positions the quinone such that in going from its ground state to the corresponding radical anion upon acceptance of an electron, there is minimal loss in resonance energy and minimal gain in steric interactions.

Synthesis and evaluation of selected analogs of the invention has shown that the electron donor/acceptor properties of the ubiquinone core can be fine-tuned. Applied computational methods accurately reproduce experimentally determined redox potentials in a series of CoQ₁₀ analogs, as well as anticipate geometries of substituents on the quinone nucleus. This combination of synthesis and theory may lead to an analog better matched with complexes I and II in human mitochondria, and hence, improved capability to support respiratory function and energy production.

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference for all purposes.

Claims

1. A compound having a structure which is a member selected from Formulae (I) and (II):

2. The compound of claim 1, wherein n is selected from 4 to 11.

3. The compound of claim 2, wherein n is selected from 5 to 9.

4. The compound of claim 3, wherein n is 9.

5. The compound of claim 3, wherein R1 is a member selected from H and CH3.

6. The compound of claim 3, wherein R2 and R3 are members independently selected from H, unsubstituted alkyl, unsubstituted alkoxy, halogen substituted alkyl, and halogen substituted alkoxy.

7. The compound of claim 1, wherein said compound has a reduction potential that is lower than the reduction potential of CoQ10.

8. A compound having a structure according to Formula (III):

9. The compound of claim 8, wherein Z is a halogen.

10. A compound having a structure according to Formula (VII):

11. The compound according to claim 10, wherein Y is a halogen.

12. The compound according to claim 10, wherein R5 comprises a structure according to Formula (VI):

13. A pharmaceutical composition comprising a compound of claim 1, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

14. A method of making the compound of claim 1 having a structure according to Formula (I), comprising:

15. The method of claim 14, wherein Z is a halogen.

16. The method of claim 14, wherein (L)pM- is (CH3)2Al—.

17. A method of making the compound of claim 1 having a structure according to Formula (I), comprising: (a) contacting a compound having a structure according to Formula (VIII): wherein R1, R2 and R3 are members independently selected from H, halogen, CN, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl, wherein R2 and R3, together with the carbon atoms to which they are attached, are optionally joined to form a 5- to 7-membered ring, with the proviso that (i) when R1 is a member selected from H and unsubstituted C1-C2 alkyl, R2 and R3 are not both unsubstituted C1-C2 alkyl; (ii) when R1 is a member selected from H and substituted or unsubstituted alkyl, R2 and R3 are not both substituted or unsubstituted alkoxy; (iii) when R1 is a member selected from H and C1-C2 unsubstituted alkyl, R2 and R3 are not joined to form an unsubstituted phenyl ring; R4 is a protecting group; and R5 is a member selected from branched, unsaturated alkyl, —C(O)H, and CH2Y, wherein Y is a leaving group; and R8 and R9 are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl and substituted or unsubstituted heterocycloalkyl, and an organometallic species having a structure according to Formula (IV): wherein L is an organometallic ligand; M is a metal; n is an integer from 0 to 13; p is an integer selected from 1 to 5, wherein each of said p organometallic ligands is independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl; in the presence of a catalyst effective at catalyzing coupling between said C** according to Formula (VIII) and said organometallic species according to Formula (IV), thereby forming a compound according to Formula (IX): (b) removing R4, thereby producing a compound according to Formula (X). (c) contacting the compound according to Formula (X) with an oxidant; thereby producing the compound having a structure according to Formula (I).

18. The method of claim 17, wherein Y is a halogen.

19. The method of claim 17, wherein (L)pM- is (CH3)2Al—.

20. A method of making the compound of claim 1 having a structure according to Formula (II), comprising: (a) synthesizing a compound according to Formula (I) by the method of claim 14 or by the method of claim 17;(b) reducing the product of step (a), thereby forming the compound having a structure according to Formula (II).

21. A method for treating a condition, which is a member selected from a neurological disorder, a mitochondrial disease and a heart disease, said method comprising administering to a subject in need thereof a therapeutically effective amount of a compound according to claim 1 or a pharmaceutically acceptable salt or solvate thereof.

22. The method of claim 21, wherein said subject is a human.

23. The method of claim 21, wherein said neurological disorder is a member selected from Huntington's disease and Parkinson's disease.

24. The method of claim 21, wherein said mitochondrial disorder is a member selected from progressive external opthalmoplegia, diabetis mellitus, deafness, Leber hereditary optic neuropathy, mitochondrial encephalomyopathy, lactic acidosis, stroke-like syndrome, myoclonic epilepsy, ragged-red fibers, Leigh syndrome, subacute sclerosing encephalopathy, neuropathy, ataxia, retinitis pigmentosa, ptosis, Kearns-Sayre syndrome and myoneurogenic gastrointestinal encephalopathy.