Face-to-face/face-to-edge interactive chiral selectors and related apparatuses

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the separation of enantiomers, i.e., those isomers in which the arrangement of atoms or groups is such that the two molecules are not superimposable. The invention more particularly relates to a chiral selector useful, for example, as a chiral stationary phase (CSP) in the liquid chromatographic separation (HPLC) of enantiomers of non-steroidal anti-inflammatory agents.
2. Description of the Prior Art
Stereoisomers are those molecules which differ from each other only in the way their atoms are oriented in space. Stereoisomers are generally classified as diastereomers or enantiomers; the latter embracing those which are mirror-images of each other, the former being those which are not. The particular arrangement of atoms that characterize a particular stereoisomer is known as its optical configuration, specified by known sequencing rules as, for example, either + or - (also D or L) and/or R or S.
Though differing only in orientation, the practical effects of stereoisomerism are important. For example, the biological and pharmaceutical activities of many compounds are strongly influenced by the particular configuration involved. Indeed, many compounds are only of widespread utility when employed in a given stereoisomeric form.
Living organisms usually produce only one enantiomer of a pair. Thus only (-)-2-methyl-1-butanol is formed in yeast fermentation of starches; only (+)-lactic acid is formed in the contraction of muscle; fruit juices contain only (-)-malic acid, and only (-)-quinine is obtained from the cinchona tree. In biological systems, stereochemical specificity is the rule rather than the exception, since the catalytic enzymes, which are so important in such systems, are optically active. For example, the sugar (+)-glucose plays an important role in animal metabolism and As the basic raw material in the fermentation industry; however, its optical counterpart, or antipode, (-)-glucose, is neither metabolized by animals nor fermented by yeasts. Other examples in this regard include the mold Penicillium glaucum, which will only consume the (+)-enantiomer of an enantiomeric mixture of tartaric acid, leaving the (-)-enantiomer intact. Also, only one stereoisomer of chloromycetin is an antibiotic; and (+)-ephedrine not only does not have any drug activity, but it interferes with the drug activity of its antipode. Finally, in the world of essences, the enantiomer (-)-carvone provides oil of spearmint with its distinctive odor, while its optical counterpart (+)-carvone provides the essence of caraway.
Accordingly, it is desirable and oftentimes essential to separate stereoisomers in order to obtain the useful version of a compound that is optically active.
Separation in this regard is generally not a problem when diastereomers are involved: diastereomers have different physical properties, such as melting points, boiling points, solubilities in a given solvent, densities, refractive indices etc. Hence, diastereomers are normally separated from one another by conventional methods, such as fractional distillation, fractional crystallization, or chromatography.
Enantiomers, on the other hand, present a special problem because their physical properties are identical. Thus they cannot as a rule--and especially so when in the form of a racemic mixture--be separated by ordinary methods: not by fractional distillation, because their boiling points are identical; not by conventional crystallization because (unless the solvent is optically active) their solubilities are identical; not by conventional chromatography because (unless the adsorbent is optically active) they are held equally onto the adsorbent. The problem of separating enantiomers is further exacerbated by the fact that conventional synthetic techniques almost always produce a mixture of enantiomers. When a mixture comprises equal amounts of enantiomers having opposite optical configurations, it is called a racemate; separation of a racemate into its respective enantiomers is generally known as a resolution, and is a process of considerable importance.
Various techniques for separating enantiomers are known. Most, however, are directed to small, analytical quantities, meaning that other drawbacks aside, when applied to preparative scale amounts (the milligram to kilogram range) a loss of resolution occurs. Hand separation, the oldest method of resolution, is not only impractical but can almost never be used since racemates seldom form mixtures of crystals recognizable as mirror images.
Another method, known as indirect separation, involves the conversion of a mixture of enantiomers--the racemate--into a mixture of diastereomers. The conversion is accomplished by reacting the enantiomers with an optically pure derivatizing agent. The resultant diastereomers are then separated from one another by taking advantage of their different physical properties. Once separated by, for example, fractional crystallization, or more commonly, chromatography, the diastereomers are re-converted back into the corresponding enantiomers, which are now optically pure. Though achieving the requisite separation, the indirect method suffers in that it is time consuming and can require large quantities of optically pure derivatizing agent which can be expensive and is oftentimes not recoverable. Moreover, the de-derivatizing step may itself result in racemization thus defeating the purpose of the separation earlier achieved.
A more current method that avoids some of the drawbacks attendant the indirect method is known as the direct method of separation. The direct method, much like the indirect method, involves the formation of a diastereomeric species. However, unlike the indirect method, this species is transient, with the stability of one species differing from the other.
In one application of the direct method, the mixture of enantiomers is allowed to interact with a chiral stationary phase which, for example, could reside in a chromatographic column. The enantiomer that interacts more strongly with the chiral stationary phase will have a longer residence time, hence a separation of enantiomers will occur. When the mode of interaction with the chiral stationary phase can be characterized, the elution order can be predicted. Examples of chiral stationary phases include those based upon (L)-N-(3,5-dinitrobenzoyl)leucine, which is useful in separating enantiomers of N-aryl derivatized amino acids and esters, and those based upon (L)-N-(1-naphthyl)leucine which has been used to effectively separate N-(3,5-dinitrobenzoyl) derivatized amino compounds. HPLC columns packed with silica-bonded CSP's of a variety of pi-electron acceptors and pi-electron donors--including derivatives of phenylglycine, leucine, naphthylalanine and naphthylleucine are commercially available from Regis Chemical Company, Morton Grove, Ill.
In another application of the direct method, disclosed in copending and commonly assigned U.S. patent application Ser. No. 528,007, filed May 23, 1990, now U.S. Pat. No. 5,080,795, enantiomers of such compounds as amino acids, amino esters, alcohols, amines, sulfonic acids or derivatives thereof are separated by means of a liquid membrane containing a chiral carrier, such as the derivatized amino acid (S)-N-(1-naphthyl)leucine octadecyl ester. The chiral carrier is capable of forming a stable complex with one of the enantiomers. The liquid membrane is located on one side of a semi-permeable barrier, and the mixture of enantiomers is located on the other side of the barrier. The liquid membrane containing the chiral carrier impregnates the semi-permeable barrier under conditions effective to permit or cause a stable complex between the chiral carrier and one of the enantiomers to form in the barrier. The liquid membrane containing the stable complex is passed to a second location where the conditions are effective to dissociate the stable complex, allowing the recovery of the complex-forming enantiomer to take place. In one embodiment of this application, a hollow fiber membrane is employed as the semi-permeable barrier.
It is widely recognized that stereoisomers of pharmaceutical agents may have drastically different pharmacological potencies or actions. Among those pharmaceutical agents known to elicit differing physiological responses depending on the optical configuration used are the antiphlogistics, which are those drugs used to counteract inflammation. Antiphlogistics are generally divided into two classes: nonsteroidal anti-inflammatory agents (NSAIAs), which are generally employed in the symptomatic treatment of inflammation, such as occurs with arthritis, and antirheumatics, which act in a more therapeutic fashion.
While NSAIAs can have vastly different chemical structures, most are aryl acidic molecules (though the acidic function is not essential for anti-inflammatory activity) or metabolic precursors thereof, often possessing two to three aromatic or heteroaromatic rings, either fused or linear and which are often non-planar; the presence of a halogen or isostere atom or group usually enhances activity. Nonsteroidal anti-inflammatory agents are generally categorized into the following groups: 1) salicylates, which are derivatives of salicylic acid and include agents such as aspirin; 2) 5-pyrazolone derivatives, most of which are 3,5-pyrazolidinedione derivatives and include agents such as phenylbutazone; 3) fenamates and isosteres, which are either n-arylanthranilic or 2-aminonicotinic acid derivatives, which include such agents as meclofenmate sodium; 4) oxicams, which are mostly N-heterocyclic carboxamides of 4-hydroxy-2H-1,2-benzothiazine 1,1-dioxide, and include such agents as piroxicam; 5) other acidic compounds, such as aminobenzoic acid salts (e.g. aminobenzoate potassium), pyrocathecol derivatives (e.g. nepitrin) and the sulfonanilide derivative, nimesulide; and 6) nonacidic heterocyclic compounds, such as indazole derivatives.
The more commonly employed NSAIAs, however, are those in the category known as arylacetic acid compounds. Most arylacetic acid compounds share certain structural features: a carboxyl group or its equivalent, such as enolic acid, hydroxamic acid, sulfonamide, or a tetrazole moiety, separated by one carbon atom from a planar aromatic nucleus (hence making them acidic molecules). To the flat aromatic nucleus, one or more large lipophilic groups may be attached. The presence of an .alpha.-methyl substituent normally enhances potency, while an increase in size of this .alpha.-substituent usually diminishes activity.
Generally, the category known as arylacetic acid compounds is subdivided into the following subgroups: phenylacetic acid compounds, such as diclofenac sodium; phenylpropionic acid compounds, such as ibuprofen and naproxen; phenylbutyric acid compounds, such as indobufen; aryloxyalkanoic acid compounds, such as furobufen; and heteroarylacetic acid compounds, such as etodolac.
Given the importance of nonsteroidal anti-inflammatory agents, arylacetic acid compounds in particular, and of the criticality of employing the proper enantiomeric form, much effort has been made investigating methods for obtaining the desired optical configuration of these compounds. These techniques have ranged from attempts at synthesizing one of the two optical isomers in pure form in the first instance, to tailoring the more traditional methods of enantiomer separation to meet this particular need.
While asymmetric synthesis would theoretically reduce or eliminate the need for complex stereospecific separations, these synthetic techniques have met with limited commercial success in general applications, and have had even less success with respect to nonsteroidal anti-inflammatory agents. Stereochemical isolation and purification of these compounds have thus far relied upon chromatographic separation techniques.
Of the separation techniques in this regard, most have required derivatization of the particular NSAIA involved with some techniques even employing a chiral derivatizing agent so as to form diastereomers. However, these derivatization-dependent methods introduce increased time and cost factors into the separation and, even more importantly, introduce the possibility of error into the separation process, which now requires further steps and reactions to achieve resolution, which itself may prove to be ultimately less effective.
Procedures which require derivatization of NSAIAs with chiral reagents in order to obtain diastereomers are particularly problem prone, given that the rate of reaction of the chiral reagent with individual enantiomers may be different thus leading to a ratio of diastereomers which does not reflect the initial ratio of analyte enantiomers. Further, these procedures require scrupulous maintenance of the enantiomeric purity of the chiral reagent and avoidance of partial racemization of the analyte and chiral reagent during the course of the derivatization procedure. Lastly, the diastereomeric product ultimately obtained may give nonidentical detection results, thus requiring additional validation steps.
Accordingly, to avoid these drawbacks, efforts have been made to obtain direct chromatographic separation of underivatized NSAIA enantiomers. However, these efforts have failed to be generally applicable to the entire class of NSAIAs, and have failed to be even generally applicable to any category of NSAIAs, such as the arylacetic acid category, which includes naproxen and other profen-type agents. For example, Hermansson and Eriksson in "Direct Liquid Chromatographic Resolution of Acidic Drugs Using Chiral .alpha.-1-Acid Glycoprotein Column (Enantiopace.RTM.), J. Liq. Chromatogr., 9, 621 (1986) report a chromatographic separation factor (.alpha.) of greater than 4 for underivatized naproxen using an .alpha.-1-acid glycoprotein chiral stationary phase and an achiral ion pairing reagent. However, the separation of enantiomers using a protein-derived stationary phase suffers from several important drawbacks which make these methods less than desirable for practical applications: First, since proteins are only available in one enantiomeric form, or antipode, elution orders cannot be reversed, which is often desirable in the analytical determination of enantiomeric purity. And, in any event, if a chiral selector is to find practical application as an enantioselective membrane transport agent, it is desirable that it be available in both enantiomeric forms. Secondly, proteins and protein-derived chiral stationary phases typically have rather low stability compared to synthetic chiral selectors, thus the lifetime of a protein selector or a chiral stationary phase derived therefrom, will not be as great as that for a synthetic selector; this is especially true where elevated temperatures, extremes of pH or organic solvents are involved. Finally, owing to the extremely low concentration of binding sites on the protein, preparative scale resolutions are not feasible.
Other efforts in this regard include that reported by Petterson and Gloeli in "Improved Resolution of Enantiomers of Naproxen by the Simultaneous Use of a Chiral Stationary Phase and a Chiral Additive in the Mobile Phase", J. Chromatogr., 435, 225 (1988) in which underivatized enantiomers of naproxen were separated on a quinidine-based chiral stationary phase using quinine as a mobile phase additive. Separation, however, was marginal, with .alpha.=1.18, and poor band shape was exhibited, hence making this technique impractical for preparative purposes.
Thus there continues to be a pressing need for a process of separating enantiomers of NSAIAs, especially those categorized as arylacetic acid compounds, which does not require derivatization and which is not protein-based and which can provide a high degree of resolution and is generally applicable at least across an entire category of NSAIAs.
SUMMARY OF THE INVENTION
The present invention overcomes the inadequacies attendant enantiomeric separation techniques known heretofore for nonsteroidal anti-inflammatory agents. The present invention is directed to a chiral selector which can enantioselectively complex with underivatized nonsteroidal anti-inflammatory agents, particularly those classified as arylacetic acid compounds and hence provide a process for the efficient separation of the enantiomers of these compounds.
The chiral selector of the present invention is a compound having the formula: ##STR1## wherein ##STR2## R.sub.2 is O, S or NH; R.sub.3 and R.sub.4 are each independently hydrogen or lower alkyl;
R.sub.5 is hydrogen or CH.dbd.CH.sub.2 ;
R.sub.6 and R.sub.7 are each independently hydrogen or lower alkyl or R.sub.6 and R.sub.7 are attached to form a 6 member aromatic ring;
X is O, S, NH or CH;
X.sub.1 is O, S, NH or CH;
m is 0 or 1;
n is 0 or 1;
R.sub.8 and R.sub.9 are each independently NO.sub.2, N(R.sub.10).sub.3.sup.+ CN, COOR.sub.11, SO.sub.3 H or COR.sub.12, wherein R.sub.10, R.sub.11 and R.sub.12 are each independently hydrogen or lower alkyl; and
o is 0 or an integer from 1 to 12, said compound being an R or an S enantiomer or a mixture of R and S enantiomers.
In one embodiment of the subject invention, the chiral selector is employed in a process of separating enantiomers of a nonsteroidal anti-inflammatory agent having a first and second optical configuration, wherein said nonsteroidal anti-inflammatory agent has the formula: ##STR3## wherein R.sub.13 is aryl or a nitrogen, sulfur or oxygen containing heterocyclic moiety either of which may be unsubstituted or substituted with lower alkyl, lower alkoxy, aryl, aryloxy, aroyl, alkanoyl or halogen, and
R.sub.14 and R.sub.15 are each independently hydrogen or lower alkyl,
with a chiral selector having the formula described hereinbefore, said chiral selector being an R or S enantiomer under conditions effective to form a complex between an enantiomer of said non-steroidal anti-inflammatory agent having said first optical configuration and an enantiomer of said chiral selector; and
recovering the non-complexed enantiomer of said non-steroidal anti-inflammatory agent having said second optical configuration.
In another embodiment of the present invention, the chiral selector is employed in a process of separating enantiomers of various amines, alcohol-derivatives, sulfoxides and epoxides, respectively.
The present invention is also directed to an apparatus utilizing the chiral selector. Apparatuses in this regard include liquid chromatographic columns, enantioselective membrane transport devices and liquid-liquid partitioning devices, such as countercurrent chromatographic devices.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates in one embodiment to a process for the enantiomeric separation of nonsteroidal anti-inflammatory agents, particularly those agents categorized generally as arylacetic acid compounds and more particularly those groups known as phenylpropionic acid compounds and heteroarylacetic acid compounds. The present invention further relates to a chiral selector compound having a certain structure, the use of which achieves the enantiomeric separation. Significantly, in the practice of the invention, no derivatization of the enantiomers is required prior to effecting separation, although derivatization may be employed without detriment.
The process of the invention has especial utility in separating enantiomers of underivatized arylacetic acid compounds. This class of nonsteroidal anti-inflammatory agents may be identified by the general formula: ##STR4## wherein R.sub.13 is an aryl or a nitrogen, sulfur or oxygen containing heterocyclic moiety, either of which may be unsubstituted or substituted with lower alkyl, lower alkoxy, aryl, alkoxyaryl, aralkyl, aryloxy, aroyl, alkanoyl, aralkanoyl or halogen, and
R.sub.14 and R.sub.15 are each independently hydrogen or lower alkyl.
These compounds are of the R of S optical configuration and when prepared are normally produced in racemic form, thus making enantiomeric separation a necessity for practical purposes.
Among the preferred arylacetic acid compounds which may be enantiomerically separated by the process of the present invention are those generally in the subgroup known as phenylpropionic acid compounds and heteroarylacetic acid compounds.
Representative compounds of the phenylpropionic acid subgroup include: alminoprofen, benoxaprofen, carprofen, cicloprofen, cinaproxen, cliprofen, dexindoprofen, esflurbiprofen, fenclorac, fenoprofen, fenoprofen calcium, flunoxaprofen, fluprofen, flurbiprofen, frabuprofen, furaprofen, furcloprofen, hexaprofen, ibufenac, ibuprofen, ibuprofen aluminum, ibuproxam, indoprofen, isoprofen, ketoprofen, lisiprofen, lobuprofen, loxoprofen, mexoprofen, miroprofen, naproxen, naproxen sodium, naproxol, piketoprofen, pimaprofen, pineprofen, pirprofen, pranoprofen, protizinic acid, rosmarinic acid, suprofen, tazeprofen, tetriprofen, ximoprofen and zoliprofen.
Representative compounds of heteroarylacetic acid subgroup include: acemetacin, anirolac, bensuldazic acid, bufezolac, cinmetacin, clidanac, clometacin, clopirac, delmetacin, duometacin, eltenac, etodolac, fenclozic acid, fentiazac, glucametacin, indomethacin, indomethacin sodium trihydrate, isofezoluc, ketorolac, lonazolac, calcium niometacin, orpanoxin, oxametacin, oxaprozin, pimetacin, pirazolac, prodolic acid, proglumetacin, sermetacin, sulindac, talmetacin, tianafac, tiaprofenic acid, tioxaprofen, tolmetin, tolmetin sodium, zidometacin and zomepirac sodium.
The structures of the more preferred compounds of these groups to which the present process has particular utility are given, in Table 1, below: ##STR5##
The present process is most utile in performing enantiomeric separation on naproxen.
The substituents in the formulas related herein are described as follows:
As employed herein, the lower alkyl groups, singly or in combination with other groups, contain up to 6 carbon atoms which may be in the normal or branched configuration, including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, pentyl, hexyl and the like. The preferred alkyl groups contain 1 to 3 carbon atoms.
The aryl groups are aromatic rings containing from 6 to 14 carbon atoms. Examples of aryl groups include phenyl, .alpha.-naphthyl and .beta.-naphthyl.
The alkoxyaryl groups, singly or in combination with other groups, contain up to 16 carbon atoms, with each alkoxy group containing up to 6 carbon atoms which may be in the normal or branched configuration, and each aryl group containing from 4 to 10 carbon atoms. Preferably, each alkoxy group contains to 1 to 3 carbon atoms, and each aryl group contains 4 to 6 carbon atoms.
The aralkyl groups, singly or in combination with other groups, contain up to 16 carbon atoms with each aryl group containing from 6 to 10 carbon atoms and each alkyl group containing up to 6 carbon atoms which may be in the normal or branched configuration. Preferably, each aryl group contains 6 carbon atoms and each alkyl group contains 1 to 3 carbon atoms.
The aryloxy groups, singly or in combination with other groups contain from 6 to 10 carbon atoms. Preferably, each aryl group contains 6 carbon atoms.
The aroyl groups, singly or in combination with other groups, contain from 7 to 11 carbon atoms. Preferably, the aryl group contains 6 carbon atoms.
The alkanoyl groups, singly or in combination with other groups, contain up to 7 carbon atoms. Preferably, the alkyl groups contain 1 to 3 carbon atoms.
The aralkanoyl groups, singly or in combination with other groups, contain up to 17 carbon atoms, with each aryl group containing from 6 to 10 carbon atoms and each alkyl group containing up to 6 carbon atoms. Preferably, each aryl group contains 6 carbon atoms and each alkyl group contains 1 to 3 carbon atoms.
The lower alkoxy groups, singly or in combination with other groups, contain up to 6 carbon atoms which may be in the normal or branched configuration. Preferably each alkyl group contains 1 to 3 carbon atoms.
The alkaryl groups, singly or in combination with other groups, contain up to 16 carbon atoms with each alkyl group containing up to 6 carbon atoms which may be in the normal or branched configuration, and each aryl group containing from 6 to 10 carbon atoms. Preferably, each alkyl group contains 6 carbon atoms. The aralkenyl groups, singly or in combination with other groups, contain up to 30 carbon atoms, with each aryl group containing up to 10 carbon atoms and each alkenyl group containing up to 20 carbon atoms. Preferably, each aryl group contains 10 carbon atoms and each alkenyl group contains up to 15 carbon atoms.
The halogens include fluorine, chlorine, bromine and iodine. Preferred halogens include fluorine and chlorine.
As employed herein, the expression "a nitrogen, sulfur or oxygen containing heterocyclic moiety" is meant to include those heterocyclic ring systems which include at least one sulfur, nitrogen or oxygen ring atom but which may include one or several of said atoms. The expression also includes saturated and unsaturated heterocyclics as well as heteroaromatic rings. These groups contain from 10 to 15 ring atoms on the heterocyclic moiety. Representatives heterocyclics include furan, thiophene, pyrrole, pyridine, pyrazole, pyrazine, pyrimidine, pyridazine, oxazole, quinoline, isoquinoline, indole, benzothiophene, benzofuran, imidizole, benzoxazote, piperazine, tetrahydrofuran and the like.
The chiral selector of the present invention is a compound having the following formula: ##STR6## wherein ##STR7## R.sub.2 is O, S or NH; R.sub.3 and R.sub.4 are each independently hydrogen or lower alkyl;
R.sub.5 is hydrogen or CH.dbd.CH.sub.2 ;
R.sub.6 and R.sub.7 are each independently hydrogen or lower alkyl or R.sub.6 and R.sub.7 are attached to form a 6 member aromatic ring;
X is O, S, NH or CH;
X.sub.1 is O, S, NH or CH;
m is 0 or 1;
n is 0 or 1;
R.sub.8 and R.sub.9 are each independently NO.sub.2, N(R.sub.10).sub.3.sup.+, CN, COOR.sub.11, SO.sub.3 H or COR.sub.12, wherein R.sub.10, R.sub.11, and R.sub.12 are each independently hydrogen or lower alkyl; and
o is 0 or an integer from 1 to 12, said compound being an R or an S enantiomer or a mixture of R and S enantiomers.
In the practice of the present invention, the substituents denoted above as ##STR8## may be in the trans, or the cis position relative to one another; the cis position is preferred.
In preferred embodiments of the chiral selector of the instant invention
R.sub.1 is preferably ##STR9## R.sub.2 is preferably NH. R.sub.3 and R.sub.4 are preferably each independently hydrogen or methyl, with hydrogen being more preferred.
R.sub.5 is preferably CH.dbd.CH.sub.2.
R.sub.6 and R.sub.7 are preferably attached to form a 6 member aromatic ring when X is O, S or NH, preferably O, and m is 1 and n is 0, or R.sub.6 and R.sub.7 are preferably attached to form a 6 member aromatic ring when X.sub.1 is O, S or NH, preferably O, and m is 0 and n is 1. In a more preferred embodiment, R.sub.6 and R.sub.7 are hydrogen or methyl, methyl being more preferred, and X and X.sub.1 are each CH and m and n are each 1.
R.sub.8, and R.sub.9 are preferably NO.sub.2.
A particularly preferred chiral selector for effecting separation of nonsteroidal anti-inflammatory agents, particularly those classified as arylacetic acid compounds and more particularly, those in the subgroup known as phenylpropionic acid compounds and heteroarylacetic acid compounds, is the chiral selector having the formula: ##STR10## hereinafter identified as CS-10 and also known by its name 4-(3,5-dinitrobenzoyl)amino-3-(undec-10-enyl)-1,2,3,4-tetrahydrophenanthrene.
Another preferred chiral selector for effecting separation of non-steroidal anti-inflammatory agents, particularly those classified as arylacetic acid compounds and more particularly, those in the subgroup known as phenylpropionic acid compound and heteroarylacetic acid compound is the chiral selector having the formula: ##STR11## hereinafter identified as CS-2 and also known by its name 4-oxo-3-allyl-1,2,3,4-tetrahydrophenanthrene.
Still another preferred chiral selector for effecting separation of non-steroidal anti-inflammatory agents, particularly those classified as arylacetic acid compounds and more particularly those in the subgroup known as phenyl propionic acid compound and heteroarylacetic acid compounds is the chiral selector having the formula: ##STR12## hereinafter identified as CS-8 and also known by its name 6,7-Dimethyl-4-�N-(3,5-dinitrobenzoyl)!amino-3-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene.
The present invention further relates to other chiral selectors henceforth referred to as Type 1, Type 2, Type 3, Type 4, Type 5 and Type 6. That which is denoted herein as Type 1 is a compound having the following formula: ##STR13## wherein: R.sub.42 and R.sub.43 are each independently hydrogen, OH or lower alkyl, or R.sub.42 and R.sub.43 are joined to form a 6-member aromatic ring;
X.sub.2 and X.sub.3 are each independently O, S, N, NH or R.sub.48 wherein each R.sub.48 is independently hydrogen, OH or lower alkyl;
a is 0 or 1;
b is 0 or 1;
X.sub.4 and X.sub.5 are each independently O, S, NH or CH.sub.2 ; R.sub.45 and R.sub.46 are each independently hydrogen or lower alkyl;
R.sub.47 is hydrogen or CH.dbd.CH.sub.2 ;
R.sub.44 is ##STR14## R.sub.48 and R.sub.49 are each independently hydrogen; NO.sub.2, N(R.sub.51).sub.3.sup.+, CN, CF.sub.3, COOR.sub.52, SO.sub.3 H or COR.sub.53 wherein R.sub.51, R.sub.52 and R.sub.53 are each independently hydrogen or lower alkyl; and
c is 0 or an integer from 1 to 12, said compound being an R or S enantiomer or a mixture of R and S enantiomers.
In practicing the present invention, the substituents denoted as: ##STR15## may be in either the cis or trans configuration relative to each other, the cis being preferred.
In the preferred practice of Type 1, R.sub.44 is ##STR16## X.sub.2 and X.sub.3 are each CH and a and b each 1. It is further preferred if R.sub.42, R.sub.43, R.sub.44, R.sub.45 and R.sub.46 are each hydrogen, R.sub.49 and R.sub.50 are each NO.sub.2 and X.sub.5 is NH. Of this, it is particularly desired that X.sub.4 is NH, R.sub.47 is CH.dbd.CH.sub.2 and c is 0, the resultant selector in this regard, denoted for convenience as CST1-1, being: ##STR17##
In another aspect of this embodiment, x.sub.4 is 0, R.sub.47 is CH.dbd.CH.sub.2 and c is 0, the structure of this selector, denoted herein as CST1-2 being depicted below as: ##STR18##
The chiral selector that is denoted as Type 2 is a compound having the following formula: ##STR19## wherein: R.sub.54, R.sub.55, R.sub.56, R.sub.57 and R.sub.58 are each independently hydrogen, OH or lower alkyl, or R.sub.54 and R.sub.55 are joined to form a 6-member aromatic ring, or R.sub.54, R.sub.55 and R.sub.56 are joined to form a 10-member aromatic ring, or R.sub.54, R.sub.55, R.sub.56 and R.sub.57 are joined to form a 14-member aromatic ring or R.sub.54, R.sub.55, R.sub.56, R.sub.57 and R.sub.58 are joined to form an 18-member aromatic ring, or R.sub.55 and R.sub.56 are joined to form a 6-member aromatic ring, or R.sub.55, R.sub.56 and R.sub.57 are joined to form a 10-member aromatic ring, or R.sub.55, R.sub.56, R.sub.57 and R.sub.58 are joined to form a 14-member aromatic ring, or R.sub.55 and R.sub.56 are joined to form a 6-member aromatic ring, or R.sub.56, R.sub.57 and R.sub.58 are joined to form a 10-member aromatic ring, or R.sub.57 and R.sub.58 are joined to form a 6-member aromatic ring with the proviso that if R.sub.54, R.sub.55 and R.sub.58 are each hydrogen then either one or both of R.sub.56 and R.sub.57 is OH, and with the further proviso that if R.sub.56 and R.sub.57 are joined to form a 6-member aromatic ring then each of R.sub.54, R.sub.55 and R.sub.58 are other than hydrogen;
X.sub.6 is O, S or NH;
R.sub.59 and R.sub.60 are each independently hydrogen or lower alkyl;
R.sub.61 is hydrogen or CH.dbd.CH.sub.2 ;
R.sub.62 is ##STR20## R.sub.63 and R.sub.64 are each independently hydrogen, NO.sub.2, N(R.sub.65).sub.3.sup.+, CN, CF.sub.3, COOR.sub.66, SO.sub.3 H or COR.sub.67 wherein R.sub.65, R.sub.66 and R.sub.67 are each independently hydrogen or lower alkyl; and
d is 0 or an integer from 1 to 12.
In a preferred embodiment of the above, R.sub.62 is ##STR21## and X.sub.6 is NH. It is further preferred in this regard that R.sub.63 and R.sub.64 are each NO.sub.2, that R.sub.59 and R.sub.60 are each hydrogen, that R.sub.61 is CH.dbd.CH.sub.2 and that d is 0. Three species of selector meeting the above criteria are of particular interest. In the first, denoted as CST2-1, R.sub.54, R.sub.55 and R.sub.56 are each hydrogen and R.sub.56 and R.sub.58 are joined to form a 6-member aromatic ring. CST2-1 is shown below: ##STR22##
In the second, denoted as CST2-2, R.sub.54, R.sub.55, R.sub.56 and R.sub.58 are each hydrogen and R.sub.57 is OH. CST2-2 is shown below: ##STR23##
In the third, denoted as CST2-3, R.sub.54, R.sub.55, R.sub.57 and R.sub.58 are each hydrogen and R.sub.56 is OH. CST2-3 is shown below: ##STR24##
The chiral selector contemplated herein as Type 3 is a compound having the formula: ##STR25## wherein: R.sub.68 and R.sub.69 are each independently hydrogen, OH or lower alkyl or R.sub.68 and R.sub.69 are joined to form a 6-member aromatic ring;
X.sub.7 and X.sub.8 are each independently O, S, N, NH or CR.sub.76 wherein each R.sub.76 is independently hydrogen, OH or lower alkyl;
e is 0 or 1;
f is 0 or 1;
X.sub.9 is O, S or NH;
R.sub.71, R.sub.72 and R.sub.73 are each independently hydrogen or lower alkyl;
R.sub.74 and R.sub.75 are each independently hydrogen, lower alkyl or --(CH.sub.2).sub.g --R.sub.77 wherein each R.sub.77 is hydrogen or CH.dbd.CH.sub.2 and g is 0 or an integer from 1 to 12 with the proviso that R.sub.74 and R.sub.75 not simultaneously contain CH.dbd.CH.sub.2 ; and
R.sub.70 is ##STR26## R.sub.78 and R.sub.79 are each independently hydrogen, NO.sub.2, N(R.sub.80).sub.3.sup.+, CN, CF.sub.3, COOR.sub.81, SO.sub.3 H or COR.sub.82 wherein R.sub.80, R.sub.81 and R.sub.82 are each independently hydrogen or lower alkyl.
In the practice of the Type 3 selector, it is preferred if ##STR27## X.sub.7 and X.sub.8 are each CH, e and f are each 1, R.sub.68 and R.sub.69 are each hydrogen and X.sub.9 is NH. It is further preferred that R.sub.78 and R.sub.79 are each NO.sub.2 and that R.sub.71 is hydrogen; and also that R.sub.72, R.sub.73 and R.sub.74 are each lower alkyl, preferably C.sub.1 to C.sub.3, and that R.sub.75 is --(CH.sub.2).sub.g --R.sub.77. In a specific practice of the foregoing, denoted as CST3-1, as shown below, R.sub.72, R.sub.73 and R.sub.74 are each methyl, R.sub.77 is CH.dbd.CH.sub.2 and g is 0: ##STR28##
In yet another embodiment of the Type 3 chiral selector, R.sub.72, R.sub.73 and R.sub.75 are each independently lower alkyl, preferably C.sub.1 to C.sub.3, and R.sub.74 is --(CH.sub.2).sub.g --R.sub.77 ; of this, it is more preferred if R.sub.72, R.sub.73 and R.sub.75 are each methyl, R.sub.77 is CH.dbd.CH.sub.2 and g is 0. The resultant selector, denoted as CST3-2, is shown below: ##STR29##
The chiral selector known herein as Type 4 is a compound having the formula: ##STR30## wherein: R.sub.83 and R.sub.84 are each independently hydrogen, OH, lower alkyl or R.sub.83 and R.sub.84 are joined to form a 6-member aromatic ring;
X.sub.10 and X.sub.11 are each independently O, S, N, NH or CR.sub.87 wherein each R.sub.87 is independently hydrogen, OH or lower alkyl;
h is 0 or 1;
i is 0 or 1;
R.sub.85 is hydrogen or CH.dbd.CH.sub.2 ;
j is 0 or an integer from 1 to 12; and
R.sub.86 is ##STR31## wherein each X.sub.12 is independently a halogen and each R.sub.88 is independently hydrogen, NO.sub.2, N(R.sub.89).sub.3.sup.+, CN, CF.sub.3, COOR.sub.90, SO.sub.3 H or COR.sub.91 wherein R.sub.89, R.sub.90 and R.sub.91 are each independently hydrogen or lower alkyl.
Here, it is preferred if R.sub.83 and R.sub.84 are each hydrogen, X.sub.10 and X.sub.11 are each CH, h and i are each 1 and R.sub.85 is CH.dbd.CH.sub.2 with j equal to 1. Two particularly preferred embodiments of this configuration are contemplated. In the first, R.sub.86 is ##STR32## the final structure, denoted as CST4-1, being shown below: ##STR33##
In the second, R.sub.86 is ##STR34## the resultant structure, denoted as CST4-2, being shown below: ##STR35##
The chiral selector referred to as Type 5, is a compound having the following formula: ##STR36## wherein: R.sub.92 and R.sub.93 are each independently hydrogen, OH, lower alkyl or R.sub.92 and R.sub.93 are joined to form a 6-member aromatic ring;
X.sub.13 and X.sub.14 are each independently O, S, N, NH or CR.sub.96 wherein each R.sub.96 is independently hydrogen, OH or lower alkyl;
t is 0 or 1;
.mu. is 0 or 1;
X.sub.15 is O, S or NH;
R.sub.94 is benzyl or naphthyl either of which may be unsubstituted or substituted with one or more lower alkyl, OH or halogen groups or R.sub.94 is --(CH.sub.2).sub.w --R.sub.97 wherein R.sub.97 is hydrogen or CH.dbd.CH.sub.2 and w is 0 or an integer from 1 to 12; and
R.sub.95 is hydrogen or CH.dbd.CH.sub.2 ; and
v is 0 or an integer from 1 to 12
with the proviso that R.sub.95 is other than CH.dbd.CH.sub.2 when R.sub.94 is --(CH.sub.2).sub.w --R.sub.97 and R.sub.97 is CH.dbd.CH.sub.2.
In a preferred practice of the Type 5 selector, R.sub.92 and R.sub.93 are each hydrogen, X.sub.13 and X.sub.14 are each CH, t and .mu. are each 1 and X.sub.5 is NH. Three particularly preferred embodiments utilize this configuration. In the first, denoted as CST5-1 and shown below, R.sub.94 is ##STR37## R.sub.95 is CH.dbd.CH.sub.2 and v is 1: ##STR38##
In the second, denoted as CST5-2 and shown below, R.sub.94 is --(CH.sub.2).sub.2 --R.sub.97 is hydrogen, w is an integer from 1 to 6, R.sub.95 is CH.dbd.CH.sub.2 and v is 1: ##STR39##
In the third, denoted as CST5-3 end shown below, R.sub.94 is --(CH.sub.2).sub.w --R.sub.97 wherein R.sub.97 is CH.dbd.CH.sub.2, w is 2, R.sub.95 is hydrogen and v is 0: ##STR40##
The chiral selector denominated as Type 6 is a compound having the formula: ##STR41## wherein: R.sub.98 and R.sub.99 are each independently hydrogen, OH, lower alkyl or R.sub.98 and R.sub.99 are joined to form a 6-member aromatic ring;
X.sub.16 and X.sub.17 are each independently O, S, N, NH or CR.sub.101 wherein each R.sub.101 is independently hydrogen, OH or lower alkyl;
x is 0 or 1;
y is 0 or 1;
X.sub.18 is O, S or NH;
X.sub.19, X.sub.20 and X.sub.21 are each independently CR.sub.102 R.sub.103 or --N--(CH.sub.2).sub.z --R.sub.104 wherein R.sub.102 and R.sub.103 are each independently hydrogen or lower alkyl, R.sub.104 is hydrogen or CH.dbd.CH.sub.2 and z is 0 or an integer from 1 to 12 with the proviso that one of X.sub.19, X.sub.20 or X.sub.21 be N--(CH.sub.2).sub.z --R.sub.104 ; and
R.sub.101 IS ##STR42## R.sub.105 and R.sub.106 are each independently hydrogen, NO.sub.2, N(R.sub.107).sub.3.sup.+,CN, CF.sub.3, COOR.sub.108 and R.sub.109 are each independently hydrogen or lower alkyl.
In a preferred embodiment, R.sub.98 and R.sub.99 are each hydrogen, X.sub.16 and X.sub.17 are each CH, x and y are each 1, R.sub.18 is NH and R.sub.100 is ##STR43##
In a more preferred embodiment, R.sub.105 and R.sub.106 are each NO.sub.2, X.sub.20 and X.sub.21 are each CH.sub.2 and X.sub.19 is --N--(CH.sub.2).sub.z --R.sub.105 wherein R.sub.104 is CH.dbd.Ch.sub.2 and z is 1; this particular embodiment is denoted as CST6-1 and is shown below: ##STR44##
The present invention further contemplates an apparatus for the separation of enantiomers which comprises an R or S enantiomer of the chiral selectors of Types 1, 2, 3, 4, 5 and 6, respectively. It is particularly preferred in this regard if the apparatus is a liquid chromatography column having a stationary phase comprising an R or S enantiomer of the compounds hereinbefore described and depicted as CST1-1, CST1-2, CST2-1, CST2-2, CST2-3, CST3-1, CST3-2, CST4-1, CST4-2, CST5-1, CST5-2, CST5-3 and CST6-1, respectively, immobilized on a support effective for use in chromatographic separation.
In an especially preferred embodiment in this regard, the support is silica or alumina, silica being preferred, and the R or S enantiomers of the selectors of Types 1-6 listed above are immobilized to the silica conventional means, preferably by way of monofunctional or multifunctional linkages. Chiral stationary phases contemplated in this regard employing the aforementioned selectors of Types 1-6 are illustrated below: ##STR45##
In another embodiment of the present invention, the chiral selector having the formula described hereinabove is employed in a process for the separation of enantiomers of amines having the general formula: ##STR46## wherein R.sub.16 and R.sub.17 are each independently hydrogen, aralkyl, aralkenyl or R.sub.16 and R.sub.17 together with the N to which they are attached form a 3, 4, 5 or 6 member ring having the general formula: ##STR47## wherein R.sub.21 and R.sub.22 are each independently hydrogen, lower alkyl, aryl, alkaryl or aralkyl and q is 1, 2, 3 or 4, R.sub.18 is C or S, R.sub.19 is lower alkyl, aryl, alkaryl or aralkyl any of which may be unsubstituted or substituted with NO.sub.2, N(R.sub.23).sub.3.sup.+, CN, COOR.sub.24, SO.sub.3 H or COR.sub.25 wherein R.sub.23, R.sub.24 and R.sub.25 are each independently hydrogen or lower alkyl, R.sub.20 is O and p is 1 when R.sub.18 is S, and p is 0 when R.sub.18 is C.
Representative amines having this formula are shown in Table 2, below:
TABLE 2__________________________________________________________________________ ##STR48## ##STR49##__________________________________________________________________________
In yet another embodiment of the present invention, the chiral selector having the formula described hereinabove is employed in a process for the separation of enantiomers of alcohol derivatives having the general formula: ##STR50## wherein R.sub.26 is hydrogen, lower alkyl or aryl either of which may be unsubstituted or substituted with NO.sub.2, N(R.sub.29).sub.3 CN, COOR.sub.30, SO.sub.3 H or COR.sub.31 wherein R.sub.29, R.sub.30 and R.sub.31 are each independently hydrogen or lower alkyl, R.sub.27 is NR.sub.32 wherein R.sub.32 is hydrogen or lower alkyl, R.sub.28 is lower alkyl, aryl or aralkyl and r is 0 or 1.
Representative alcohol derivatives having this formula are shown in Table 3, below:
TABLE 3______________________________________ ##STR51## ##STR52## ##STR53##______________________________________
In still another embodiment of the present invention, the chiral selector having the formula described hereinabove is employed in a process for the separation of enantiomers of epoxides having the general formula: ##STR54## wherein R.sub.33, R.sub.34, R.sub.35 and R.sub.36 are each independently hydrogen, lower alkyl, aryl, alkaryl or aralkyl.
Representative epoxides having this formula are shown in Table 4, below:
TABLE 4______________________________________ ##STR55## ##STR56##______________________________________
In yet still another embodiment of the present invention, the chiral selector having the formula described hereinabove is employed in a process for the separation of enantiomers of sulfoxides having the general formula ##STR57## wherein R.sub.37 and R.sub.38 are each independently lower alkyl or an aryl or a nitrogen, sulfur or oxygen containing heterocyclic moiety, or R.sub.37 or R.sub.38 may together with the S to which they are attached from a 4 or 5 member ring having the formula: ##STR58## wherein R.sub.39 is hydrogen or lower alkyl, R.sub.40 is O or S, R.sub.41 is aryl and s is 1 or 2.
Representative sulfoxides having this formula are shown in Table 5, below:
TABLE 5______________________________________ ##STR59##______________________________________
The chiral selectors of the present invention may be prepared by conventional chemical preparation techniques. For illustrative purposes, the preparation of the preferred chiral selector is described below but those skilled in the art can readily appreciate the modifications necessary to prepare other chiral selectors within the scope of the formula depicted hereinabove.
The synthetic sequence used to prepare the chiral selector of the present invention is exemplified for CS-10, as shown in Table 7, below. Those of skill in the art will appreciate that the synthetic sequence delineated hereinbelow is readily modified to provide other chiral selectors of the instant invention.
TABLE 7__________________________________________________________________________ ##STR60## ##STR61##__________________________________________________________________________
This preparation began with 4-oxo-1,2,3,4-tetrahydrophenanthrene (identified as Compound A, Table 7), as described by Scroeter, G. et al. In "Uber die Hydrierung des Phenanthrens, Ber. der. Deutschen Chem, 62, 645, 1929. Alkylation of this phenanthrene with 11-iodoundec-1-ene was performed in refluxing benzene using potassium t-butoxide as a base. Reductive alkylation of the resulting monoalkylated ketone (identified as Compound B, Table 7), using sodium cyanoborohydride and ammonium acetate in isopropyl alcohol at 95.degree. C. gave a mixture of cis- and trans- amines (identified as Compound C, Table 7), which were converted to the corresponding 3,5-dinitrobenzamides (identified as CS-10, Table 7), without purification. The mixture of cis- and trans- amides (about 5:1) was then separated by flash chromatography upon silica gel. Enantiomeric separation was performed at this stage using a preparative version of a chiral stationary phase described by Pirkle, Deming and Burke in Chirality, 3:183-187 (1991) the contents of which are incorporated herein by reference; this chiral stationary phase was derived from S-N-(1-naphthyl) leucine and having the formula: ##STR62##
Enantiomeric separation by means of the chiral selectors of the invention may be achieved in a variety of techniques known in the art. In one embodiment, the chiral selector may form the active portion of the stationary phase in an HPLC column. In this embodiment of the present invention, the terminal W of the formula, or R.sub.47 in the case of the chiral selector of Type 1; or R.sub.61 in the case of Type 2; or R.sub.74 or R.sub.75 in the case of Type 3, or R.sub.85 in the case of Type 4, or R.sub.95 in the case of Type 5, or R.sub.104 in the case of Type 6, must be CH.dbd.CH.sub.2 so as to permit the chiral selector to be immobilized on a support which is suitable for use in chromatographic separations. Supports in this regard include, e.g., silica and alumina. In one configuration, the chiral selector is immobilized by covalently bonding it to silanized silica. Thus, for example as shown in Table 8, below, hydrosilation of enantiomerically pure CS-10 gives a silane (identified as Compound D, Table 8) which was bonded to 5.mu. (100 .ANG. silica gel and slurry packed into a stainless steel analytical HPLC column (4.6 mm.times.250 mm) to give a chiral stationary phase based on CS-10 (CSP-10)).
TABLE 8__________________________________________________________________________ ##STR63## ##STR64## ##STR65## ##STR66## ##STR67##__________________________________________________________________________
Since the chiral selectors of the invention are optically active, it is necessary to separate the chiral selectors so that either the R or the S enantiomer of the chiral selector is employed as the stationary phase in the column, depending upon which of the enantiomers to be separated is to be preferentially bound to the chiral selector.
The techniques of enantiomer separation by HPLC are known in the art. Commercially available HPLC columns employing chiral stationary phases, such as those available from Regis Chemical Company, can be employed in practicing the subject invention. See, for example, "Systematic Studies of Chiral Recognition Mechanisms", W. H. Pirkle, et al., Pages 23-25 in "Chiral Separations", Stephenson and Wilson, eds. Plenum Press, New York, 1988, the contents of which are incorporated herein by reference.
In another embodiment of the present invention, the chiral selectors of the subject invention may be employed to effect separations using semi-permeable membranes wherein the chiral selector forms part of a mobile phase. Such techniques are also well known, including the use of semi-permeable membranes in the form of hollow fiber membranes. In this embodiment, it is preferred that the terminal W in the formula of the chiral selector, or R.sub.47 in the case of the chiral selector of Type 1; or R.sub.61 in the case of Type 2; or R.sub.74 or R.sub.75 in the case of Type 3, or R.sub.85 in the case of Type 4, or R.sub.95 in the case of Type 5, or R.sub.104 in the case of Type 6, be hydrogen so as to minimize covalent bonding by the chiral selector. In one particularly useful embodiment, the chiral selector forms part of a liquid membrane passing on one side of a semi-permeable barrier with enantiomers to be separated passing on the other side of the barrier. The pores of the membrane become impregnated with the liquid membrane containing the chiral selector. One of the enantiomers forms a complex with the chiral selector, passes through the membrane into the moving liquid membrane and is conducted to a second location wherein disassociation takes place. This technique is disclosed in commonly assigned U.S. patent application Ser. No. 528,007, filed May 23, 1990, now U.S. Pat. No. 5,080,795, the contents of which are incorporated herein by reference.
In yet another sense the present invention is directed to a chiral selector having a preorganized conformation whereby the selector manifests as part of its active portion a structural alignment of aromatic or like moieties (which are generally flat or planar and which accordingly having faces and edges) that permits substantially simultaneous interaction to occur between relevant faces and edges of said moieties and those presented by a target enantiomer-analyte.
In one aspect, the aforementioned alignment is such that a cleft is formed in the active portion of the selector. For example, the compound which comprises the selector can contain aromatic moieties that are disposed relative to each other such that a face of one moiety is substantially perpendicular to a face of another moiety, they being further positioned at an appropriate distance from one another so as to form an enantioselective notch or slot (referred to herein as a cleft) in the salient part of the selector molecule.
Enantioselective, as that word is used in this regard, denotes a specific interaction between the chiral selector and a target analyte. That is, it refers to a situation wherein a target analyte having at least one aromatic or like moiety, has a face of that moiety interact with one of the faces forming the selector cleft while, at substantially the same time, an edge of that same target moiety interacts with one of the other faces forming the cleft.
An example of a pre-organized conformation which manifests said enantioselective cleft is found in parent application U.S. Ser. No. 763,043 filed Sep. 20, 1991 (now abandoned) wherein CS-10, also known a 4-(3,5-dinitrobenzoyl)amino-3-(undec-10-enyl)-1,2,3,4-tetrahydrophenanthrene, and a chiral stationary phase, denoted CSP 10, deriving from the same are disclosed. In the conformation of this particular selector, which exemplifies, without restriction, the aspect of the invention under present consideration, the dinitrophenyl and naphthyl moieties are disposed relative to each other such that a cleft, as hereinbefore described, is formed therebetween. This cleft is moreover enantioselective, as earlier defined, in that when an analyte containing an aromatic moiety (such as naproxen, which contains a naphthyl moiety) interacts with it, the resultant chiral recognition occurs primarily by a mechanism which involves a substantially simultaneous complexation between a face and edge of that moiety with the faces of the dinitrobenzyl and naphthyl moieties, respectively which form the cleft in the selector.
Thus in a preferred embodiment of this aspect of the present invention, it is contemplated that a chiral selector having the pre-organized conformation described hereinabove will provide simultaneous face-to-face .pi.--.pi. interaction and face-to-edge .pi.--.pi. interaction between the cleft of the selector and the target analyte; it is also contemplated as a further preferred embodiment in this regard that hydrogen bonding, insofar as is available, will also concurrently occur between the selector and the analyte.
Face-to-edge .pi.--.pi. complexes, as such, are not unknown and have been reported in other contexts--namely, in crystal protein structures, see Burley, S. K., et al., Science (1985), 229, 23; in peptides, see Siemion, I. Z. Z., Naturforsch B. (1990) 45(a), 1324 and small molecules, see Moehldorf, A. V., et al., J. Am. Chem. Soc. (1988), 110, 6561. These types of complexes have also been implicated in the binding of aromatic quests by paracyclophene hosts, see Ferguson, S. B., et al., J. Am. Chem. Soc. (1991) 113, 5410.
Indeed, while certain commercially available chiral stationary phases--for example, those which employ derivatives of 3,5-dinitrobenzoyl phenylglycine and 3,5-dinitrobenzoyl naphthylglycine, and that which is marketed as B-Gem I, contain the requisite dramatic moieties, these are not in a pre-organized conformation, as is the selector of the present invention. Specifically, the relevant moieties in these known selectors are flexible relative to each other; e.g., the phenyl or naphthyl group is attached to the remainder of the selector compound by only one bond. Thus rotation, which is a form of flexibility, can occur, which circumstance means that any alignment relative to the dinitrobenzoyl moiety is not maintained or maintainable.
Unlike these configurations, the chiral selector of the present invention is pre-organized; that is, the requisite aromatic moieties are not only sufficiently close together and properly oriented in space to provide the cleft contemplated, but they are also sufficiently rigid so as to effectively prevent undesired rotation and flexibility. Thus in the chiral selector of the present invention, the enantioselective cleft is maintained, which circumstance effectively results in a consistently higher degree of chiral recognition. Rigidity and resultant cleft maintenance is, in one embodiment, obtained by having the one of the involved aromatic moieties of the selector, which is preferably a .pi.-basic moiety, e.g., an electron-rich phenyl or naphthyl moiety, have more than one point of attachment to the compound which otherwise comprises the selector.
A preferred manner of attachment in this regard is by having a cyclic moiety, e.g., cyclohexyl ring, as an integral part of the molecular structure. For example, in aforementioned CS-10, a cyclohexyl ring is used to contain the stereogenic center bearing the dinitrobenzamide group and is also to control the orientation of the .pi.-basic naphthyl system. The net overall effect is that by integrating the cyclohexyl ring into the molecular structure, a degree of conformational rigidity heretofore unknown is provided and the enantioselective cleft thus formed is maintained. Other methods of achieving such rigidity and cleft maintenance will, given the foregoing, be readily appreciated to those of skill in the art.

The following examples are given to illustrate the scope of the invention. Because these examples are given for illustrative purposes only, the invention embodied therein should not be limited thereto.
EXAMPLE 1
Preparation of CS-10
Apparatus and Materials
Chromatographic analysis was performed using a Rainin HPX Rabbit pump, a Rheodyne Model 7125 injector with a 20 .mu.l sample loop, a Milton Roy-LDC UV absorbance Monitor D.RTM. fixed wavelength detector operating at 254 nm, and a Shimadzu CR1A integrating recorder.
Solvents used were HPLC grade or were distilled prior to use. (S)-naproxen was used as received from Sepracorp. Dimethylchlorosilane was obtained from Petrarch Chemicals.
Preparation of 4-(3,5-dinitrobenzoyl)amino-3-(undec-10-enyl)-1,2,3,4-tetrahydrophenanthrene (CS-10) (see Table 7, supra)
Synthesis of 11-Iodoundec-1-ene
A solution of 93.5 g of undec-10-en-1-ol and 100 mL of triethylamine in 500 mL of dry dichloromethane was treated with 68.7 g of methanesulfonyl chloride at 0.degree. C. according to the method reported by Crossland, R. K., et al. in "A Facile Synthesis of Methanesulfonate Esters" J. Org. Chem., 35, 3195 (1970). The crude reaction mixture was then evaporated and partitioned between water and ether. The ether layer was collected, washed with water, then dried over anhydrous magnesium sulfate. Filtration and evaporation gave 142 g of a colorless oil which was immediately converted to the iodo compound. A solution of 137 g sodium iodide and 1.2 g dicyclohexano-18-crown-6 in 150 mL of water was stirred with 64 g of the crude mesylate on a steam bath for 5 h. The reaction mixture was then extracted several times with ether, the combined ether fractions were washed with water, then dried over anhydrous magnesium sulfate. Filtration and evaporation gave the crude iodo compound as an oil which was vacuum distilled to give 62.8 g (90% yield) of almost colorless oil, b.p. 118.degree.-122.degree. C./4.5 mn Hg, lit. 104.degree. C./2 mm Hg. This compound was used in the synthesis of the alkylated ketone or described hereinbelow.
Synthesis of the alkylated ketone (Compound B, Table 7)
In a 1 L three-necked round bottom flask equipped with a Teflon paddle stirrer, nitrogen inlet, and a Dean-Stark trap, 500 mL of benzene was dried by azeotropic water removal. Solid potassium tert.-butoxide, 12.3 g, was added at 50.degree. C. giving a clear solution. A solution of 8.9 g of 4-oxo-1,2,3,4-tetrahydrophenanthrene, as described by Scroeter, G. et al. in "Uber die Hydrierung des Phenanthrens", Ber. der Deutschen Chem., 62, 645 (1929) (Compound A, Table 7) and 14 g of 11-iodoundec-1-ene (synthesized according to the method described above) in 100 mL of dry benzene was added at 40.degree. C., causing the reaction mixture to darken somewhat. Stirring at 40.degree. C. was continued for 45 min., then the reaction mixture was heated at reflux for 2 h. During this period, approximately 400 mL of benzene was allowed to distill off. Cooling the reaction mixture followed by extraction with water, drying the organic phase with anhydrous magnesium sulfate, filtration, and evaporation gave 19 g of a dark oil which was purified by flash chromatography on silica using 1:1 dichloromethane/hexane as eluent to give 9.9 g of alkylated ketone (Compound B, Table 2) (63% yield).
Reductive amination to form 4-amino-3-(undec-10-enyl)-1,2,3,4-tetrahydrophenanthrene (Compound C, Table 7)
In a 250 mL thick-walled Parr bottle was mixed 5 g of alkylated ketone (Compound B, Table 7) as synthesized according to the method described above, 6 g sodium cyanoborohydride, 30 g ammonium acetate, and 100 mL 2-propanol. After securely closing the bottle with a rubber stopper, the contents were heated to 90.degree.-95.degree. C. for 24 h by immersion of the bottle in a steam bath. A safety shield was placed in front of the bottle, which had also been wrapped in cloth. After cooling and evaporation the crude product was partitioned between ether and water, the ether layer was dried with anhydrous magnesium sulfate, filtered, and evaporated to give 5.9 g of an oil which showed no traces of alkylated ketone (Compound B, Table 7) by thin layer chromatography (TLC). The crude amine was carried on to the next step without further purification.
Synthesis of 4-(3,5-dinitrobenzoyl)amino-3-(undec-10-enyl)-1,2,3,4-tetrahydrophenanthrene (CS-10)
The crude amine synthesized according to the method described above was dissolved in 150 mL dichloromethane and stirred with excess saturated sodium hydrogen carbonate solution. 3,5-Dinitrobenzoyl chloride, 5 g, dissolved in the minimum amount of dichloromethane was then added, and the resulting two-phase mixture was stirred vigorously for 1 h. The organic layer was then dried, concentrated to approximately 20 mL volume, and purified by flash chromatography on silica with dichloromethane as eluent. Both cis and trans isomers of CS-10 were obtained in about a 5:1 ratio, respectively. Separation of the diastereomers was incomplete by flash chromatography; nevertheless, pooling of the pure fractions containing the desired cis diastereomer gave 2.2 g of CS-10 (a 28% yield from Compound B, Table 7).
Separation of the enantiomers of CS-10
Separation of the enantiomers of CS-10 was performed with a chiral stationary phase derived from S-N-(1-naphthyl)leucine which was prepared as described by Pirkle, Deming and Burke in Chirality, 3:183-187 (1991) the contents of which are incorporated herein by reference.
Separation of the enantiomers of CS-10 was performed using this chiral stationary phase derived from S-N-(1-naphthyl)leucine at a flow rate of 40 mL/min of 10% 2-propanol in hexane with continuous redistillation and recycling of mobile phase. Two bands were obtained. 1 g samples of the nearly pure fast-eluting enantiomer of CS-10 having the (R,R) configuration were isolated, as were samples of the slow-eluting enantiomer of CS-10 having the (S,S) configuration.
Chiral Stationary Phase of CS-10
Hydrosilation of CS-10
The fast eluting enantiomer (R,R) of CS-10 was dissolved, 1 g, in a mixture of 10 mL of dimethylchlorosilane (Petrarch Chemicals) and 10 mL of dichloromethane. Chloroplatinic acid (about 10 mg), dissolved in a minimum amount of 2-propanol, was then added, and the reaction mixture was heated at reflux under a nitrogen atmosphere. After 2 h, a quenched (as described below) aliquot of the reaction mixture was subjected to TLC analysis, showing the disappearance of starting material. The reaction mixture was evaporated to dryness on a rotary evaporator to give the crude chlorosilane as a dark oil. Residual dimethylchlorosilane was removed by three successive additions and evaporations of small portions of dichloromethane. A solution of 5 mL triethylamine, 5 mL absolute ethanol, and 5 mL diethyl ether was then added to the crude chlorosilane and the mixture was stirred at room temperature under nitrogen atmosphere for 30 minutes. The mixture was then filtered to remove precipitated triethylamine hydrochloride. The filtrate was then used without further purification in the preparation of CSP-10.
Bonding to silica to form CSP-10
The filtrate from the hydrosilation of CS-10, as described above, containing the crude ethoxysilane (Compound D, Table 8) was added to 5 g Regis Rexchrom silica (5.mu., 100 .ANG.) which had been previously dried by azeotropic water removal with benzene. Dimethylformamide, (1 mL) was then added, and the slurry was carefully evaporated to dryness under reduced pressure. The moist slurry was then rocked in a Kgelrohr oven at 90.degree.-95.degree. C./1 mm Hg for 24 hours. The silica gel was then washed extensively with ethanol and then methanol, slurried in methanol and packed into a 4.6 mm.times.250 man stainless steel HPLC column to afford CSP-10. Excess silica gel removed from the column packer reservoir was submitted for elemental analysis (C 7.27%; H 0.95%; N 0.71%) to reveal a loading of 0.18 mMole chiral selector per gram of stationary phase. After preliminary analysis, the residual silanols on the stationary phase were endcapped by passing a solution of 2 mL of hexamethyldisilazane (HMDS) in 50 mL dichloromethane through the methylene chloride equilibrated column at a flow rate of 1 mL/min.
Analytes and their separation
All chromatographic experiments were carried out at a nominal flow rate of 2.00 mL/min. Column void time was measured by injection of tri-t-butylbenzene, a presumed unretained solute. Variable temperature data were collected with the mobile phase reservoir and pump at ambient temperature, and with the column immersed in a large constant temperature bath. About two feet of 0.009 in ID stainless steel tubing was used to connect the column to the injector and was wrapped around the inverted column as a heat exchanger to thermally equilibrate the mobile phase prior to column entry.
Mobile phases consisting of alkanes and lower molecular weight alcohols, and, optionally, containing lower molecular weight carboxylic acids and/or lower molecular weight amines were used to permit separation of enantiomers of naproxen and other analytes.
Enantiomeric mixtures of naproxen and selected .alpha.-arylacetic acid compounds of interest were subjected to separation with HPLC columns to compare the effectiveness of CS-10 of the present invention when forming the active part of the stationary phase (CSP-10) in the column.
Two mobile phases were separately utilized: Mobile Phase A, which comprised 5% 2-propanol and 0.1% acetic acid in hexane, and Mobile Phase B, which comprised 20% 2-propanol, 0.1% acetic acid and 0.1% triethylamine in hexane.
Chromatographic data for naproxen and nine other .alpha.-aryl acetic acid compounds were obtained using the (R,R) configuration of CS-10 of the invention. The results are presented below in Table 9.
TABLE 9______________________________________Separation of Underivatized naproxenand other arylacetic acid compounds on CSP-10 Mobile Phase A Mobile Phase BAnalyte k'.sub.1 .alpha. k'.sub.1 .alpha.______________________________________naproxen 3.31 1.97 5.86 2.20ibuprofen 0.27 1.22 0.75 1.20ketoprofen 3.11 1.05 5.08 1.22flurbiprofen 0.64 1.30 2.05 1.31pirprofen 1.85 1.27 3.35 1.33fenoprofen 0.57 1.40 1.46 1.43cicloprofen 2.53 1.60 4.00 1.67carprofen 2.20 1.40 6.30 1.42tiaprofenic acid 6.40 >1.00 13.45 1.12etodolac 0.87 1.23 -- --______________________________________ k'.sub.1 = the capacity factor for the first eluted enantiomer using the indicated mobile phases and flow rates. The detector was operating at 254 nm. .alpha. = the chromatographic separation factor
From these data, it can be seen that CSP-10 achieved a high degree of chromatographic separation (.alpha.) of the underivatized analytes. Using Mobile Phase A, all of the analytes, except ketoprofen and tiaprofenic acid, were baseline resolved under these chromatographic conditions. In mobile phases containing a small amount of triethylamine in addition to acetic acid (Mobile Phase B), baseline resolution of all the analytes was easily obtained.
Chromatographic data for the amines, alcohol derivatives, epoxides and sulfoxides shown in Tables 2, 3, 4 and 5, respectively, were obtained using the (R,R) configuration of CS-10 of the invention using either of Mobile Phase A or Mobile Phase B, or a third Mobile Phase C, which comprised 2% 2-propanol in hexane; all other conditions were as described above. The resolution results are shown in Tables 10, 11, 12, and 13, below.
TABLE 10______________________________________Separation of Amines on CSP-10______________________________________ ##STR68## ##STR69## ##STR70## ##STR71## ##STR72## ##STR73##______________________________________
TABLE 11______________________________________Separation of Alcohol Derivatives on CSP-10______________________________________ ##STR74## ##STR75## ##STR76##______________________________________
TABLE 12______________________________________Separation of Epoxides on CSP-10______________________________________ ##STR77## ##STR78##______________________________________
TABLE 13______________________________________Separation of Sulfoxides on CSP-10______________________________________ ##STR79##______________________________________
As seen from these data, high degrees of resolution, as measured by the chromatographic separation factor, .alpha., are obtained with the chiral selector of the present invention, as embodied on CSP-10.
EXAMPLE 2
Preparation of CS-2
The synthetic sequence used to prepare CS-2 is shown in Table 14, below.
TABLE 14______________________________________ ##STR80## ##STR81## ##STR82##______________________________________
Apparatus and Materials
Chromatographic analysis was performed using a Altex model 100A pump, a Rheodyne model 7125 injector with a 20 .mu.l sample loop, a Linear UVIS 200 variable wavelength absorbance monitor, set at 254 nm, and a Hewlett-Packard HP 3394A integrating recorder. All .sup.1 H NMR spectra were recorded on a Varian XL 200 FT NMR spectrometer.
All reagents were of pharmaceutical or reagent grade and were used without further purification. Solvents used were HPLC grade or distilled prior to use. Dimethylchlorosilane was obtained from Petrarch Systems, Bristol, Pa. Rexchrom 5.mu./100 .ANG. silica gel was obtained from Regis Chemical Co., Morton Grove, Ill.
Peparation of Racemic 4-oxo-3-allyl-1,2,3,4-tetrahydrophenanthrene (CS-2)
Transformation of the ketone, 4-oxo-1,2,3,4-tetrahydrophenanthrene (Compound E, Table 14), which ketone has been reported by Premasager, V. et al. in J. Org. Chem., 46, pp. 2974 (1981) to CS-2 followed the method in Example 1 for CS-10.
Alkylation of the ketone (Compound E, Table 14) with allyl bromide gave Compound F (Table 14). Reductive amination of Compound F (Table 14) followed by acylation with 3,5-dinitrobenzoyl chloride gave CS-2. .sup.1 H NMR (200 M Hz, CDCl.sub.3) .delta.: 1.60 (m, 1H), 2.10 (m, 3H), 2.65 (m, 1H), 3.19 (m, 2H), 5.12 (m, 2H), 6.00 (m, 1H), 6.18 (dd, 1H, J=10 Hz and 3 Hz), 6.34 (d, 1H, J=10 Hz), 7.29 (d, 1H), 7.45 (m, 2H), 7.79 (m, 2H), 8.05 (d, 1H, J=8.4 Hz), 8.88 (d, 2H, J=2.3 Hz).
Separation of the Enantiomers of CS-2
The enantiomers of CS-2 were chromatographically separated on a 25 mm.times.900 mm column containing a chiral stationary phase derived from (S)-N-(1-naphthyl)leucine chiral stationary phase which was prepared as described by Pirkle, Demirig and Burke in Chirality, 3:183-187 (1991) the contents of which are incorporated herein by reference.
Separation of the enantiomers of CS-2 was performed using this chiral stationary phase derived from (S)-N-(1-naphthyl)leucine at a flow rate of 40 ml/min. of 10% 2-propanol in hexane with continuous redistillation and recycling of mobile phase. Two bands were obtained. Samples of the nearly pure fast-eluting enantiomer of CS-2 having the (R,R) configuration were isolated, as were samples of the slow-eluting enantiomer of CS-2 having the (S,S) configuration (0.85 g).
Chiral Stationary Phase of CS-2
The synthetic sequence used to prepare to chiral stationary phase of CS-2 is shown in Table 15, below.
TABLE 15__________________________________________________________________________ ##STR83## ##STR84##__________________________________________________________________________
Hydrosilation of CS-2
The second eluting enantiomer of CS-2 (0.85 g) assigned the (S,S) absolute configuration by a combination of HPLC, NMR, and x-ray crystallographic evidence was dissolved in a mixture of 10 mL of dimethylchorosilane and 10 mL of dichloromethane. Elemental analysis of residual packing (C 4.95%; H 0.61%; N 0.56%) showed a loading of 2.0.times.10.sup.-4 moles of chiral selector per gram of stationary phase. The residual silanol groups were endcapped by passing a solution of 2 mL of hexamethyldisilazane in 50 mL dichloromethane through the dichloromethane equilibrated column at a flow rate of 1 mL/min.
Analytes and their Separation
All chromatographic experiments were carried out at a nominal flow rate of 2.00 mL/min. unless otherwise indicated. Column void time was measured by injection of tri-t-butylbenzene, a presumed unretained solute as reported by Pirkle, et al. in J. Liq. Chromatogr., 14, 1, (1991) incorporated herein by reference. .sup.1 H NMR chemical shifts were reported in ppm (.delta.) relative to tetramethylsilane. Variable temperature data were collected with the mobile phase reservoir and pump at ambient temperature, and with the column immersed in a large constant temperature bath. About two feet of 0.009 in ID stainless steel tubing was used to connect the column to the injector and was wrapped around the inverted column as a heat exchanger to thermally equilibrate the mobile phase prior to column entry.
Enantiomeric mixtures of naproxen and selected .alpha.-arylacetic acid compounds of interest were subjected to separation with HPLC columns to compare the effectiveness of CS-2 of the present invention, when it forms the active part of the stationary phase of the column. The separation afforded by CS-2 under these circumstances was compared with CS-10 of the present invention as prepared according to Example 1; each separately formed the active part of the stationary phase (denoted as CSP-2 and CSP-10) in the respective columns.
The mobile phase utilized comprised 20% 2-propanol in hexane containing 1 g/L ammonium acetate.
Chromatographic data for naproxen and seven other .alpha.-arylacetic acid compounds were obtained using the S,S configurations of CS-2 and CS-10 of the invention. The results are presented below in Table 16.
TABLE 16______________________________________Separation of Underivatized Naproxen andOther Arylacetic Acid Compounds on CSP-10 and CSP-2 CSP-10 CSP-2Compound k'.sub.1 k'.sub.2 .alpha. k'.sub.1 k'.sub.2 .alpha.______________________________________Naproxen 3.96 8.95 2.26 1.71 5.01 2.93Ibuprofen 0.94 1.05 1.12 0.19 0.28 1.47Ketoprofen 4.53 5.03 1.11 1.39 1.79 1.29Flurbiprofen 1.63 1.94 1.19 0.37 0.59 1.59Pirprofen 2.53 3.49 1.38 0.85 1.54 1.81Fenoprofen 1.48 1.81 1.22 0.38 0.61 2.50Cicloprofen 3.03 5.18 1.71 1.16 2.50 2.15Tiaprofenic Acid 6.15 6.70 1.09 2.02 2.48 1.23______________________________________ Conditions: Flow rate = 2.0 mL/min.; mobile phase = 20% 2propanol in hexane containing 1 g/L ammonium acetate; k'.sub.1 = Capacity factor for first eluted enantiomer. k'.sub.2 = Capacity factor for second eluted enantiomer. .alpha. = The chromatographic separation factor.
From these data, it can be seen that CSP-2 achieved an even higher degree of chromatographic separation (.alpha.) of the underivatized analytes than CSP-10, with an .alpha. for CSP-2 of nearly three (2.93, at room temperature) being obtained for naproxen. Analyte capacity factors (k's), as apparent in Table 16, were consistently less on the short-tethered CSP-2 as opposed to the longer tethered CSP-10. This was especially true for the less retained enantiomer.
EXAMPLE 3
Preparation of CS-8
Apparatus and Materials
Melting points were taken on a Buchi apparatus and are uncorrected. .sup.1 H NMR spectra were recorded on a Varian XL-200 spectrometer in CDCl.sub.3 and were referenced to tetramethylsilane or residual CHCl.sub.3 (7.24 ppm). IR spectra were taken on a IBM IR/32 FTIR spectrometer. High resolution mass spectra were obtained on a Varian 731 mass spectrometer at SCS Mass Spectrometry Laboratory, University of Illinois at Urbana-Champaign.
Chromatography was performed with a HPLC system which consists of an Anspec-Blschoff model 2200 HPLC pump, a Rheodyne 7125 injector with 20 .mu.l sample loop, a Milton Roy UV Monitor.TM.D fixed wavelength detector operating at 254 nm and a Kipp & Zonen BD 41 recorder.
Preparation of 3-(6,7-Dimethyl-1 and 2-naphthoyl)propanoic Acid
Anhydrous AlCl.sub.3 (19 g, 0.14 mole) was added to 200 ml of CH.sub.2 Cl.sub.2 with stirring at 0.degree. C. To the stirred heterogeneous solution was added succinic anhydride (12 g, 0.12 mole) and then 2,3-dimethylnaphthalene (15.6 g, 0.1 mole) at 0.degree. C. After stirring overnight at room temperature, 200 ml of 1N HCl, 10 ml of 12N HCL and then 300 ml of ethylacetate were added to the reaction mixture. The whole mixture was shaken vigorously in a separatory funnel and then the two phases (organic phase:upper phase) were separated. The organic phase was extracted with 1N NaOH. The NaOH solution was washed with ether (200 ml) and then acidified with 12N HCl to afford yellow solid material in the aqueous phase. The whole mixture was extracted with ethylacetate. The ethylacetate solution was dried over anhydrous Na.sub.2 SO.sub.4 and then concentrated to afford yellow solid material. This solid material was crystallized from ethylacetate. The first crop (6.58 g, 25.7% yield) was found to be pure 3-(6,7,-dimethyl-2-naphthoyl)propanoic acid (.beta.-isomer) and the second crop (6.85 g, 26.8% yield) was 3-(6,7-dimethyl-1-naphthoyl)propanoic acid (.alpha.-isomer) by NMR. .beta.-Isomer: yellow needle crystal, mp 183.0.degree.-185.0.degree. C., .sup.1 H NMR (CDCl.sub.3) .delta. 2.45 (s, 6H), 2.87 (t, J=6.7 Hz, 2H), 3.45 (t, J=6.7 Hz, 2H), 7.63 (s, 1H), 7.71 (s, 1H), 7.77 (d, J=8.5 Hz, 1H), 7.95 (d, J=8.5 Hz, 1H), 8.41 (s, 1H), IR (KBr) cm.sup.-1 3300-2800, 1698, 1678, 1610, 1597, Anal. calcd. for C.sub.16 H.sub.16 O.sub.3 : C, 74.98; H, 6.29. Found: C, 74.63; H, 6.17.
.alpha.-isomer: yellowish solid, mp 162.0.degree.-163.0.degree. C., .sup.1 H NMR (CDCl.sub.3) .delta. 2.42 (s, 3H), 2.44 (S, 3H), 2.89 (t, J=6.3 Hz, 2H), 3.40 (t, J=6.3 Hz, 2H), 7.37-7.44 (m, 1H), 7.62 (s, 1H), 7.87 (d, J=6.8 Hz, 1H), 7.89 (d, J=8.3 Hz, 1H), 8.43 (s, 1H), IR (KBr) cm.sup.-1 3330-2800, 1698, 1669, 1580, 1500, Anal. Calcd. for C.sub.16 H.sub.16 O.sub.3 : C, 74.98; H, 6.29. Found: C, 75.22; H, 6.18.
Preparation of 4-(6,7-Dimethyl-2-naphthyl)butanoic acid
The .beta.-isomer, 3-(6,7-dimethyl-2-naphthoyl)propanoic acid (6.58 g, 0.026 mole) was dissolved into 200 ml of THF in a hydrogenation pressure bottle. To the solution was carefully added 30% Pd/C (700 mg). The whole mixture was shaken for 15 hrs under H.sub.2 (40 psi) at room temperature. After releasing pressure, Pd/C was removed by passing the THF solution through the celite pad. The solution was concentrated to afford 4-(6,7-Dimethyl-2-naphthyl)butanoic acid as a gray solid material (6.21 g, 0.026 mole, 100% yield). mp 141.0.degree.-142.0.degree. C., .sup.1 H NMR (CDCl.sub.3) .delta. 1.98-2.12 (m, 2H), 2.36-2.41 (m, 8H), 2.81 (t, J=7.4 Hz, 2H), 7.22 (d, J=8.3 Hz, 1H), 7.49-7.55 (m, 3H), 7.65 (d, J=8.3 Hz, 1H), IR (KBr) cm.sup.-1 3700-3450,2920,1698, Anal. Calcd. for C.sub.16 H.sub.18 O.sub.2 : C, 79.31; H, 7.49. Found: C, 79.28; H, 7.49.
Preparation of 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene
4-(6,7-Dimethyl-2-naphthyl)butanoic acid (6.21 g, 0.026 mole) was added to 40 ml of CH.sub.3 SO.sub.3 H. The mixture was heated to 90.degree. C. until all solid material disappeared (about 30 min.). The mixture was poured into ice and then extracted twice with ethylacetate. Combined ethylacetate solution was dried over anhydrous Na.sub.2 SO.sub.4 and then concentrated. After flash chromatography on silica gel, 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene was obtained as a pale yellow solid material (4.96 g, 0.022 mole, 85% yield). mp 114.0.degree.-115.0.degree. C., .sup.1 H NMR (CDCl.sub.3) .delta. 2.12-2.20 (m, 2H), 2.41 (s, 3H), 2.47 (s, 3H), 2.77 (t, J=6.4 Hz, 2H), 3.09 (t, J=6.4 Hz, 2H), 7.21 (d, J=8.3 Hz, 1H), 7.54 (s, 1H), 7.31 (d, J=8.3 Hz, 1H), 9.20 (s, 1H), IR (KBr) cm.sup.-1 2930, 1669, 1590, 1510, Anal. Calcd. for C.sub.16 H.sub.16 O: C, 85.67; H, 7.19. Found: C, 86.00; H, 7.18.
Preparation of 6,7-Dimethyl-4-oxo-3-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene
t-BuOK (3.6 g, 0.032 mole) was dissolved in 250 ml of dry benzene at 40.degree.-50.degree. C. To the stirred solution was added 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene (3.6 g, 0.016 mole) in 50 ml of dry benzene and then, 10-undecenyl iodide (4.58 g, 0.016 mole) at 30.degree. C. under N.sub.2. The mixture was heated to 60.degree. C. for 2.5 hr under N.sub.2. After cooling the reaction mixture to room temperature, water was added. The whole mixture was extracted twice with diethylether. The combined diethylether solution was dried over anhydrous MgSO.sub.4 and then concentrated. Flash column chromatography of the residue on silica gel afforded 6,7-Dimethyl-4-oxo-3-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene as a sticky brown solid (2.36 g, 0.0063 mole, 39% yield) as a desired product, and unreacted 6,7-Dimethyl-4-oxo-1,2,3,4-tetrahydrophenanthrene (1.70 g, 47% recovered). .sup.1 H NMR (CDCl.sub.3) .delta. 1.29-1.62 (m, 14H), 1.86-2.08 (m, 4H), 2.21-2.35 (m, 2H), 2.40 (s, 3H), 2.46 (s, 3H), 2.52-2.63 (m, 1H), 3.07-3.13 (m, 2H), 4.90-5.04 (m, 2H), 5.75-5.89 (m, 1H), 7.17 (d, J=8.2 Hz, 1H), 7.53 (s, 1H), 7.77 (d, J=8.2 Hz, 1H), 9.10 (s, 1H), IR (KBr) cm.sup.-1 2920, 2850, 1669, 1600, exact (EI) mass. calcd. for C.sub.27 H.sub.36 O: 376.2766, Found: 376.2766.
Preparation of 6,7-Dimethyl-4-�N-(3,5-dinitrobenzoyl)!amino-3-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene C(S-8)
6,7-Dimethyl-4-oxo-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene (6.6 g, 0.018 mole) was dissolved in 300 ml of methyl alcohol in a pressure bottle. To the solution was added 60 g of ammonium acetate and 10 g of sodiumcyanoborohydride. The whole mixture was heated to 100.degree.-105.degree. C. for 48 hrs in the closed pressure bottle. After cooling down the reaction mixture to room temperature, the pressure bottle was opened carefully. After adding 200 ml of 1N HCl to the reaction mixture (which resulted in the generation of HCN gas), methyl alcohol was removed from the reaction mixture using a rotary evaporator. The residual aqueous solution was made basic (pH>10) by adding KOH pellets, and was then extracted twice with diethyl ether. The organic phase was dried over anhydrous Na.sub.2 SO.sub.4 and then concentrated to afford a viscous oily material. This viscous oily material was dissolved in 100 ml of dry CH.sub.2 Cl.sub.2. To the stirred solution was added 3,5-dinitrobenzoyl chloride (5.52 g, 0.028 mole) and triethylamine (4.2 ml, 0.030 mole). After stirring for 15 min. at room temperature, the reaction mixture was washed with 0.5N HCl, 0.5N NaOH, and then brine solution. The organic solution was dried over anhydrous Na.sub.2 SO.sub.4 and then concentrated. The residue was purified by flash column chromatography on silica gel to afford a yellowish solid material (7.66 g, 0.0134 mole, 76% yield). This solid material was found to be the mixture of cis and trans isomers of CS-8 (the ratio of cis:trans=4.9:1) by analysis on a chiral HPLC column.
Separation of the Enantiomers of CS-8
By chromatographing the mixture of cis and trans isomers of CS-8 on a (S)-N-(1-naphthyl)leucine chiral stationary phase packed into a MPLC column, which chiral stationary phase is described by Pirkle, Deming and Burke in Chirality, 3:183-187 (1991) the contents of which are incorporated herein by reference, 2.68 g of enantiomerically pure cis CS-8, i.e., (cis)-6,7-Dimethyl-4-�N-(3,5-dinitrobenzoyl)!amino-3-(10-undecenyl)-1,2,3,4-tetrahydrophenanthrene, (last eluted enantiomer) was obtained, as were samples of the trans form of CS-8 (the first eluted enantiomer). Physical data for cis CS-8, obtained as a yellowish solid, were as follows: mp 181.degree.-182.degree. C., .sup.1 H NMR (CDCl.sub.3) .delta. 1.19-1.39 (m, 14H), 1.42-1.77 (m, 3H), 1.96-2.07 (m, 4H), 2.36 (s, 3H), 2.40 (s, 3H), 3.03-3.10 (m, 2H), 4.89-5.03 (m, 2H), 5.74-5.88 (m, 1H), 6.08 (dd, J=9.2 Hz, J=2.8 Hz, 1H), 6.20 (d, J=9.2 Hz, 1H), 7.16 (d, J=8.2 Hz, 1H), 7.52 (s, 1H), 7.61 (d, J=8.2 Hz, 1H), 7.85 (s, 1H), 8.84 (d, J=1.7 Hz, 2H), 9.08 (t, J=1.7 Hz, 1H), IR (KBr) CM.sup.-1 3440, 2920, 2850, 1680, 1650, 1540, 1500, exact (EI) mass. calcd. for C.sub.34 H.sub.41 N.sub.3 O.sub.5 : 571.3046, Found: 571.3046, �.alpha.!D.sup.20 -126.2(c 091, CH.sub.2 Cl.sub.2).
Chiral Stationary Phase of (cis)-CS-8 Hydrosilation of (cis)-CS-8
Preparation of (Cis)-6,7-Dimethyl-4-�N-3,5-Dinitrobenzoyl)!amino-3-(10-dimethylethoxysilylundecyl)-1,2,3,4-tetrahydrophenanthrene
(Cis)-CS-8 (1.75 g, 3.06.times.10.sup.-3 mole) was dissolved in 20 ml of methylene chloride. To the solution were added 20 ml of dimethylchlorosilane and 0.2 ml of a H.sub.2 PtCl.sub.6 solution (72 mg of H.sub.2 PtCl.sub.6 in 5 ml of isopropyl alcohol). This mixture was refluxed under nitrogen with stirring. After refluxing for 1.5 hr., excess dimethylchlorosilane and methylene chloride were removed by simple distillation followed by application of high vacuum. The oily residue was dissolved in 30 ml of dry methylene chloride and then the mixture of ethyl alcohol and triethylamine (3 ml, 1:1 mixture) was added. After stirring for 10 min. at room temperature, all solvent was removed and the residue was purified by flash column chromatography on silica gel to afford (cis)-6,7-Dimethyl-4-�N-(3,5-Dinitrobenzoyl)!amino-3-(10-dimethylethoxysilylundecyl-1,2,3,4-tetrahydrophenanthrene as a yellowish dense liquid (0.7 g, 34% yield). .sup.1 H NMR (CDCl.sub.3) .delta. 0.09 (s, 6H), 0.54-0.62 (m, 2H), 1.18 (t, J=7.0 Hz, 3H), 1.22-1.44 (broad m, 18H), 1.50-1.80 (m, 3H), 1.95-2.13 (m, 2H), 2.34 (s, 3H), 2.40 (s, 3H), 3.05-3.08 (m, 2H), 3.65 (q, J=7.0 Hz, 2H), 6.09 (dd, J=9.2 Hz, J=3.2 Hz, 1H), 6.25 (d, J=9.2 Hz, 1H), 7.13 (d, J=8.3 Hz, 1H), 7.47 (s, 1H), 7.56 (d, J=8.3 Hz, 1H), 7.85 (s, 1H), 8.82 (d, J=2.2 Hz, 2H), 9.00 (t, J=2.2 Hz, 1H), IR (KBr) cm.sup.-1 3350, 2910, 2850, 1630, 1550, 1510, exact (EI) mass. calcd, for C.sub.38 H.sub.53 N.sub.3 O.sub.6 Si: 675.3704, Found: 675.3706, �.alpha.!D.sup.20 -82.3 (c 1.00, CH.sub.2 Cl.sub.2).
Bonding to Silica to form CSP-8
A 200 ml flask equipped with a Dean-Stark trap and a condenser was charged with 4.5 g of 5 .mu.m Rexchrom silica gel and 60 ml of benzene. After heating at reflux until water was completely removed, enantiomerically pure (cis)-6,7-Dimethyl-4-�N-(3,5-Dinitrobenzoyl)!amino-3-(10-dimethylethoxysilylundecyl)-1,2,3,4-tetrahydrophenanthrene (700 mg) in 10 ml of dry benzene was added and heated to reflux again to remove water. After removal of water, 1 ml of dimethylformamide was added and then the solvent was carefully evaporated to dryness under reduced pressure. The whole mixture was heated to 100.degree.-105.degree. C. for 2 hrs. in a Kugelrohr oven under vacuum. The silica gel was washed sequentially with benzene, methanol, ethylacetate, methylene chloride, hexane and pentane and then dried at 80.degree. C. under vacuum. Anal. Found: C 7.55%, H 0.93%, N 0.55%, calcd. loading: 0.16 mmoles of chiral selector per gram of stationary phase based on C. The modified silica gel was slurried in methanol and packed into a 4.6 mm.times.250 mm stainless steel column using a conventional method. The residual silanols were endcapped by eluting a solution of 2 ml of hexamethyldisilazane in 50 ml of methylene chloride through the CSP column previously charged with methylene chloride.
Analytes and their Separation
All chromatographic experiments were carried out at a nominal flow rate of 2.00 mL/min. unless otherwise indicated. Column void time was measured by injection of tri-t-butylbenzene, a presumed unretained solute, in the manner described by Pirkle, et al. in J. Liq. Chromatogr., 14, 1, (1991), incorporated herein by reference.
Mobile phases consisting of alkanes and lower molecular weight alcohols and, optionally containing lower molecular weight carboxylic acids and/or lower molecular weight amines were used to permit separation of enantiomers of naproxen and other analytes.
Enantiomeric mixtures of naproxen and selected .alpha.-arylacetic acid compound of interests and various analogues thereof were subjected to separation with HPLC columns to compare the effectiveness of CS-8 of the present invention when forming the active part of the stationary phase (CSP-8) in the column. The chromatographic data was obtained using the cis configuration of CS-8 of the invention. The results are presented below in Tables 17, 18, 19 and 20, which tables separately identify the mobile phases utilized.
TABLE 17______________________________________Separation of underivatized naproxen and other2-arylpropionic acids and analogues thereof on CSP-8 Mobile Elution2-Arylpropionic Acid k.sub.1 ' k.sub.2 ' .alpha. Phase Order______________________________________Naproxen 4.97 11.33 2.28 D SIbuprofen 0.69 0.83 1.20 EFlurbiprofen 1.47 2.07 1.41 EFenoprofen 1.00 1.89 1.89 ECarprofen 8.17 10.33 1.31 DPirprofen 4.50 7.11 1.58 ECicloprofen 3.29 5.59 1.70 DTiaprofenic acid 4.29 4.71 1.10 DEtodolac 3.33 4.46 1.34 E ##STR85## 5.88 19.20 3.27 D ##STR86## 4.33 12.60 2.91 D ##STR87## 3.51 12.07 3.44 D ##STR88## 2.20 2.33 1.06 D ##STR89## 0.71 1.17 1.66 D______________________________________ Mobile Phase D was 0.1% acetic acid and 5% isopropyl alcohol in hexane. Mobile Phase E was 0.1% acetic acid and 2% isopropyl alcohol in hexane. Flow rate was 2 ml/min. k.sub.1 ' = The capacity factor for the first eluted enantiomer using the indicated mobile phases and flow rates. k.sub.2 ' = The capacity factor for the second eluted enantiomer using th indicated mobile and flow rates. .alpha. = The chromatographic separation factor.
From the date of Table 17, it can be seen that CSP-8 achieved a high degree of chromatographic separation (.alpha.) of the underivatized analytes, especially naproxen.
Chromatographic data for the separation of underivatized naproxen and other arylacetic acid compounds using the cis-configuration of CSP-8 and Mobile Phase F which comprises 20% isopropyl alcohol in hexane containing 1.00 ml acetic acid/L (0.1%) and 1 ml of triethylamine/L (0.1%), is shown in Table 18 below.
TABLE 18______________________________________Separation of Underivatized Naproxen andOther Acrylacetic Acids on CSP-8 using Mobile Phase FSolutes k.sub.1 ' k.sub.2 ' .alpha.______________________________________Naproxen 5.36 15.04 2.81Ibuprofen 0.43 0.60 1.40Ketoprofen 3.00 4.26 1.42Flurbiprofen 1.36 2.44 1.80Fenoprofen 0.87 1.94 2.23Carprofen 3.39 4.71 1.39Piprofen 2.73 5.26 1.93Cicloprofen 4.00 8.39 2.10Tiaprofenic acid 7.94 10.36 1.30Etodolac 2.13 2.40 1.13 ##STR90## 4.47 14.59 3.26______________________________________ k.sub.1 ' = The capacity factor for the first eluted enantiomer using the indicated mobile phase and flow rate. k.sub.2 ' = The capacity factor for the second eluted enantiomer using th indicated mobile phase and flow rate. .alpha. = The chromatographic separation factor.
As can be seen from the data elucidated in Table 18 high levels of chromatographic separation were obtained. Indeed, as compared to that elucidated in Table 17 (using CSP-8 and Mobile Phases D and E), an increase in chromatographic separation (.alpha.) for naproxen, ibuprofen and etodolac was obtained using CSP-8 in conjunction with Mobile Phase F.
Chromatographic data for the separation of enantiomers of 3,5-Dinitrobenzamides of 1-(p-methoxyphenyl)alkylamines on CSP-8 (cis configuration) using-Mobile Phase G which comprised 30% isopropyl alcohol in hexane, is shown in Table 19, below. Flow rate was 20 ml/min.
TABLE 19______________________________________Separation of Enantiomers of 3,5-Dinitrobenzamides of 1-(p-methoxyphenyl)alkylanines on CSP-8 using Mobile Phase G ##STR91## k.sub.1 ' k.sub.2 ' .alpha.______________________________________R = CH.sub.3 15.07 36.26 2.41R = CH.sub.2 CH.sub.3 10.99 24.86 2.26R = (CH.sub.2).sub.2 CH.sub.3 11.69 24.41 2.09R = (CH.sub.2).sub.3 CH.sub.3 11.01 24.86 2.26R = (CH.sub.2).sub.4 CH.sub.3 10.71 23.29 2.17R = (CH.sub.2).sub.5 CH.sub.3 10.20 22.86 2.24R = (CH.sub.2).sub.6 CH.sub.3 9.84 22.57 2.29R = (CH.sub.2).sub.7 CH.sub.3 9.40 22.03 2.34R = (CH.sub.2).sub.8 CH.sub.3 8.90 21.50 2.42R = (CH.sub.2).sub.9 CH.sub.3 7.57 18.69 2.47R = (CH.sub.2).sub.10 CH.sub.3 7.30 18.43 2.52R = (CH.sub.2).sub.12 CH.sub.3 6.93 18.41 2.66R = (CH.sub.2).sub.14 CH.sub.3 6.29 17.40 2.77R = (CH.sub.2).sub.16 CH.sub.3 5.64 16.29 2.89______________________________________ k.sub.1 ' = The capacity factor for the first eluted enantiomer using the indicated mobile phase and flow rate. k.sub.2 ' = The capacity factor for the second eluted enantiomer using th indicated mobile phase and flow rate. .alpha. = The chromatographic separation factor.
As seen from the data of Table 19, high levels of chromatographic separation (.alpha.) was achieved for all the 3,5-dinitrobenzamides of 1-(p-methoxyphenyl)alkylamines that were studied using CSP-8 and Mobile Phase G.
Chromatographic data for the separation of a variety of other racemic compounds on CSP-8 (cis configuration) are shown in Table 20 below. The mobile phases utilized for the experiments reported in Table 20 comprised the percentage of isopropyl alcohol indicated in Table 20, in hexane. Flow rate was 2 ml/min.
TABLE 20__________________________________________________________________________Separation of a variety of RacemicCompounds on CSP-8 using the Mobile Phase havingthe Percentage of Isopropyl Alcohol indicated in Hexane % isopropylSolutes k.sub.1 ' k.sub.2 ' .alpha. alcohol in hexane__________________________________________________________________________ ##STR92## 7.56 10.14 1.34 10% ##STR93## 5.60 8.21 1.47 10% ##STR94## 3.43 10.43 3.04 5% ##STR95## 0.43 1.37 3.20 20% ##STR96## 0.47 1.17 2.48 20% ##STR97## 2.79 6.89 2.47 20% ##STR98## 0.57 0.90 1.58 20% ##STR99## 1.14 1.83 1.60 20% ##STR100## 1.14 1.86 1.63 20% ##STR101## 0.67 1.20 1.79 20% ##STR102## 0.99 2.29 2.32 20% ##STR103## 0.99 1.29 1.30 20% ##STR104## 2.06 2.91 1.42 20% ##STR105## 1.44 1.90 1.32 20% ##STR106## 8.57 23.43 2.73 20% ##STR107## 3.13 3.63 1.16 10% ##STR108## 3.70 7.91 2.14 20% ##STR109## 1.14 2.00 1.75 10%__________________________________________________________________________ k.sub.1 ' = The capacity factor for the first eluted enantiomer using the mobile phase and flow rate indicated. k.sub.2 ' = The capacity factor for the second eluted enantiomer using th mobile phase and flow rate indicated. .alpha. = The chromatographic separation factor.
As apparent from Table 20, CS-8 of the present invention, forming the active portion of chiral stationary phase CSP-8, showed high degrees of chromatographic separation (.alpha.) over a wide range of different racemates.
EXAMPLE 4
Preparation of CST1-1
The synthetic sequence to prepare CST1-1 is shown below: ##STR110##
The compounds and procedures employed to prepare compounds 1, 2 and 3 are fully described in Example 2.
Procedure for Step 1 above
The amine, 3, is dissolved in toluene in a round bottomed flask. 1.1 eq. 3,5-dinitrobenzoyl azide is added, and the mixture is heated to reflux for 30 minutes, then allowed to cool to room temperature. Solvent removed by rotary evaporation, and compound 7 (CST1-1) is purified by flash chromatography on silica.
The preparation of 3,5-dinitrobenzoyl azide and its use for making urea derivatives of amines 1s described in "Separation of the Enantiomers of 3,5Dinitrophenyl Carbamates and 3,5-Dinitrophenyl Ureas", Pirkle, W. H., et al.; J. Liq. Chromatogr. 9, 443-453 (1986).
EXAMPLE 5
Preparation of CSPT1-1
Compound 7 from Example 4 is resolved, hydrosilylated, quenched and bonded to silica in the manner described in Example 2 to thus form the chiral stationary phase denoted herein as CSPT1-1.
EXAMPLE 6
Preparation of CST4-1
The synthetic sequence to prepare CST4-1 is shown below: ##STR111##
The preparation of compound 3 is described in Example 2.
Procedure for Step 1 above:
The amine, 3, is placed In a round bottomed flask. 1 eq. tetrachlorophthalic anhydride (Aldrich) is added, and the mixture is heated at 120.degree. overnight. The following morning the reaction is cooled to room temperature, and the crude product, 8, (CST4-1) is purified by flash chromatography on silica.
EXAMPLE 7
Preparation of CSPT4-1
Compound 8 from Example 6 is resolved using an N-2-naphthylalanine chiral stationary phase or other suitable CSP, hydrosilylated, quenched and bonded to silica in the manner described in Example 2 to thus form the chiral stationary phase denoted herein as CSPT4-1.
EXAMPLE 8
Preparation of CST4-2
The synthetic sequence to prepare CST4-2 is shown below: ##STR112##
The preparation of compound 3 is described in Example 2.
Procedure for Step 1 above:
The amine, 3, is placed in a round bottomed flask fitted with a Dean-Stark trap. 2,4,5,7-tetranitrofluorenone (1.1 eq.) is added as a toluene solution, and the mixture is heated with azeotropic water removal for 12 h. The reaction mixture is then cooled, and solvent is removed under reduced pressure to afford crude product, 9 (CST4-2), which is purified by flash chromatography on silica.
EXAMPLE 9
Preparation of CSPT4-2
Compound 9 from Example 8 is resolved using an N-2-naphthylalanine chiral stationary phase or other suitable CSP, hydrosilylated, quenched and bonded to silica in the manner described in Example 2 to thus form CSPT4-2.
EXAMPLE 10
Preparation of CST5-1
The synthetic sequence to prepare CST5-1 is shown below: ##STR113##
The preparation of compound3 is described in Example 2.
Procedure for Step 1 above:
The, amine, 3, is placed in a round bottomed in dichloromethane. 1.1 equivalents of triethylamine is added with stirring, and the flask is cooled in an ice-water bath. 1-naphthoyl chloride (1.0 eq., Aldrich) is then added, keeping the reaction temperature below 5.degree. C. The solution is allowed to stir for 30 minutes, then the ice bath is removed, and the reaction is allowed to stir for an additional hour while warming to room temperature. The reaction mixture is then transferred to a separatory funnel, and washed 3.times. with 1M HCl solution. The dichloromethane layer is washed once with brine, dried over anhydrous magnesium sulfate, and evaporated to dryness to afford the crude product, 10 (CST5-1), which is purified by flash chromatography on silica.
EXAMPLE 11
Preparation of CSPT5-1
The enantiomers of Compound 10 are resolved using a DNB-phenylglycine chiral stationary phase (Pirkle 1A, Regis Technologies).
The thus resolved enantiomers are hydrosilylated, quenched and bonded to silica in the manner described in Example 2 to thus form CSPT5-1.
EXAMPLE 12
Preparation of CST5-2 and CSPT5-2
The general procedure for the preparation of CST5-2 and CSTP5-2 is as described in Examples 10 and 11 for the preparation of CST5-1 and CSTP5-1, except that various acid chlorides can be substituted for 1-naphthoyl chloride. The resolution of the resulting amide enantiomers is accomplished on DNB-phenylglycine CSP.sup.- (Pirkle 1A, Regis Technologies), the remaining protocol being the same.
EXAMPLE 13
Preparation of CST1-2
The synthetic sequence to prepare CST1-2 is shown below: ##STR114## Procedure for Step 1 above:
The ketone, 2, is place in a round bottomed flask equipped with a magnetic stir bar and nitrogen atmosphere. Dry ether is then added, and 1 eq. lithium aluminum hydride (LAH, Adlrich) is then carefully added to the stirring cooled (ice bath) reaction mixture. The mixture is allowed to stir for 30 minutes, then carefully quenched by the addition of ethanol. Solvent is removed by evaporation and the crude alcohol 11, is purified by flash chromatography on silica. (Two different diastereomers, cis and trans, are possible in this reduction).
Procedure for Step 2 above:
The alcohol, 11, is dissolved in toluene in a round bottomed flask. 1.1 eq. 3,5-dinitrobenzoyl azide is added, and the mixture is heated to reflux for 30 minutes, then allowed to cool to room temperature. Solvent removed by rotary evaporation, and compound 12 (CST1-2) is purified by flash chromatography on silica.
The preparation of 3,5-dinitrobenzoyl azide and its use for making urea derivative of amines is described in "Separation of Enantiomers of 3,5-Dinitrophenyl Carbamates and 3,5-Dinitrophenyl Ureas", Pirkle, et al. J. Liq. Chromatogr. 9, 443-453 (1986).
EXAMPLE 14
Preparation of CSPT1-2
Compound 12 from Example 13 is resolved, hydrosilylated, quenched and bonded to silica in the manner described in Example 2 to thus form the chiral stationary phase denoted herein as CSTP1-2.
EXAMPLE 15
Preparation of CST2-1 and CSPT2-1
The procedure to prepare CST2-1 and CSPT2-1 is as described in Example 2 with the exception that the starting ketone is: ##STR115##
EXAMPLE 16
Preparation of CST2-2, CST2-3, CSPT2-2 and CSPT2-3
The procedure to prepare CST2-2 and CST2-3 is as described in Example 2 with the exception that the starting ketone is a substituted naphthylene having the formula: ##STR116##
The resolution, hydrosilylation, quenching and bonding to silica to prepare CSPT2-2 and CSPT2-3 from CST2-2 and CST2-3 is as described in Example 2.
EXAMPLE 17
Preparation of CST6-1 and CSPT6-1
The procedure to prepare CST6-1 is as described in Example 2 with the exception that the starting ketone contains an olefin functionality and has the formula: ##STR117##
All subsequent steps, including reductive amination, acylation, resolution, hydrosilylation, quenching and silica immobilization are as set forth in Example 2.
EXAMPLE 18
Preparation of CST3-2 and CSPT3-2
The synthetic procedure to prepare CST3-2 is shown below: ##STR118##
1-bromo-2-methyl-naphthylene is prepared by conventional bromination of 2-methylnaphthylene, commercially available.
To a solution of 1-bromo-2-methyl naphthylene in dry ether are added clean magnesium turnings. The mixture is refluxed for several minutes until formation of the Grignard reagent is complete. The solution of Grignard reagent is then carefully transferred to an addition funnel under nitrogen atmosphere and slowly added to a solution of 2,2-dimethyl pentenoyl chloride at -78.degree. C. 2,2-dimethyl pentenoyl chloride can be made from the corresponding acid using oxalyl chloride. The 2,2-dimethyl pentenoic acid can be made from the corresponding aldehyde by oxidation. The synthesis of the aldehyde has been described by R. Salomon and J. Ghosh, Org. Synth. 63, 125 (1984).
The solution is stirred at -78.degree. C. for 2 hours, then warmed to room temperature. Solvent removal by rotary evaporation affords crude ketone which is purified by flash chromatography.
Subsequent steps of reductive amination, acylation, hydrosilylation and quenching and silica immobilization to eventually form CSPT3-2 are described in Example 2.
EXAMPLE 19
Preparation of CST5-3
Reductive amination of the ketone: ##STR119## using the reductive amination procedure described in Example 2 affords the amine having the formula: ##STR120##
Acylation of this amine with an acid chloride having a terminal olefin, e.g., pentencyl chloride (Aldrich), affords the amine product, CST5-3.
Resolution, hydrosilylation, quenching and silica immobilization, using the procedures described in Example 2, affords CSPT5-3.

Number	Name	Date
4318819	Malloy	Mar 1982
4318820	Malloy	Mar 1982
4322310	House	Mar 1982
4512898	Oi	Apr 1985
4604207	Oi	Aug 1986
4818394	Okamoto	Apr 1989
4824950	Barcza	Apr 1989
4909935	Bradshaw et al.	Mar 1990
4919803	Doyle et al.	Apr 1990
4959935	Bradshaw et al.	Oct 1990
5080795	Pirkle	Jan 1992
5256293	Pirkle	Oct 1993
5387338	Pirkle	Feb 1995
5484530	Pirkle	Jan 1996

	Number	Date	Country
Parent	89861	Jul 1993
Parent	847449	Mar 1992

	Number	Date	Country
Parent	321200	Oct 1994
Parent	763043	Sep 1991

Face-to-face/face-to-edge interactive chiral selectors and related apparatuses

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