Tetrazole-substituted arylamides as P2X3 and P2X2/3 antagonists

FIELD OF THE INVENTION

This invention pertains to compounds useful for treatment of diseases associated with P2X purinergic receptors, and more particularly to P2X₃and/or P2X_2/3antagonists usable for treatment of genitourinary, pain, gastrointestinal and respiratory diseases, conditions and disorders.

BACKGROUND OF THE INVENTION

The urinary bladder is responsible for two important physiological functions: urine storage and urine emptying. This process involves two main steps: (1) the bladder fills progressively until the tension in its walls rises above a threshold level; and (2) a nervous reflex, called the micturition reflex, occurs that empties the bladder or, if this fails, at least causes a conscious desire to urinate. Although the micturition reflex is an autonomic spinal cord reflex, it can also be inhibited or mediated by centers in the cerebral cortex or brain.

Purines, acting via extracellular purinoreceptors, have been implicated as having a variety of physiological and pathological roles. (See, Burnstock (1993) Drug Dev. Res. 28:195-206.) ATP, and to a lesser extent, adenosine, can stimulate sensory nerve endings resulting in intense pain and a pronounced increase in sensory nerve discharge. ATP receptors have been classified into two major families, the P2Y- and P2X-purinoreceptors, on the basis of molecular structure, transduction mechanisms, and pharmacological characterization. The P2Y-purinoreceptors are G-protein coupled receptors, while the P2X-purinoreceptors are a family of ATP-gated cation channels. Purinergic receptors, in particular, P2X receptors, are known to form homomultimers or heteromultimers. To date, cDNAs for several P2X receptors subtypes have been cloned, including: six homomeric receptors, P2X₁; P2X₂; P2X₃; P2X₄; P2X₅; and P2X₇; and three heteromeric receptors P2X_2/3, P2X_4/6, P2X_1/5(See, e.g., Chen, et al. (1995) Nature 377:428-431; Lewis, et al. (1995) Nature 377:432-435; and Burnstock (1997) Neuropharmacol. 36:1127-1139). The structure and chromosomal mapping of mouse genomic P2X₃receptor subunit has also been described (Souslova, et al. (1997) Gene 195:101-111). In vitro, co-expression of P2X₂and P2X₃receptor subunits is necessary to produce ATP-gated currents with the properties seen in some sensory neurons (Lewis, et al. (1995) Nature 377:432-435).

P2X receptor subunits are found on afferents in rodent and human bladder urothelium. Data exists suggesting that ATP may be released from epithelial/endothelial cells of the urinary bladder or other hollow organs as a result of distention (Burnstock (1999) J. Anatomy 194:335-342; and Ferguson et al. (1997) J. Physiol. 505:503-511). ATP released in this manner may serve a role in conveying information to sensory neurons located in subepithelial components, e.g., suburothelial lamina propria (Namasivayam, et al. (1999) BJU Intl. 84:854-860). The P2X receptors have been studied in a number of neurons, including sensory, sympathetic, parasympathetic, mesenteric, and central neurons (Zhong, et al. (1998) Br. J. Pharmacol. 125:771-781). These studies indicate that purinergic receptors play a role in afferent neurotransmission from the bladder, and that modulators of P2X receptors are potentially useful in the treatment of bladder disorders and other genitourinary diseases or conditions.

Recent evidence also suggests a role of endogenous ATP and purinergic receptors in nociceptive responses in mice (Tsuda, et al. (1999) Br. J. Pharmacol. 128:1497-1504). ATP-induced activation of P2X receptors on dorsal root ganglion nerve terminals in the spinal cord has been shown to stimulate release of glutamate, a key neurotransmitter involved in nociceptive signaling (Gu and MacDermott, Nature 389:749-753 (1997)). P2X₃receptors have been identified on nociceptive neurons in the tooth pulp (Cook et al., Nature 387:505-508 (1997)). ATP released from damaged cells may thus lead to pain by activating P2X₃and/or P2X_2/3containing receptors on nociceptive sensory nerve endings. This is consistent with the induction of pain by intradermally applied ATP in the human blister-base model (Bleehen, Br J Pharmacol 62:573-577 (1978)). P2X antagonists have been shown to be analgesic in animal models (Driessen and Starke, Naunyn Schmiedebergs Arch Pharmacol 350:618-625 (1994)). This evidence suggests that P2X₂and P2X₃are involved in nociception, and that modulators of P2X receptors are potentially useful as analgesics.

Other researchers have shown that P2X₃receptors are expressed in human colon, and are expressed at higher levels in inflamed colon than in normal colon (Y. Yiangou et al, Neurogastroenterol Mot (2001) 13:365-69). Other researchers have implicated the P2X₃receptor in detection of distension or intraluminal pressure in the intestine, and initiation of reflex contractions (X. Bian et al., J Physiol (2003) 551.1:309-22), and have linked this to colitis (G. Wynn et al., Am J Physiol Gastrointest Liver Physiol (2004) 287:G647-57).

Inge Brouns et al. (Am J Respir Cell Mol Biol (2000) 23:52-61) found that P2X₃receptors are expressed in pulmonary neuroepithelial bodies (NEBs), implicating the receptor in pain transmission in the lung. More recently, others have implicated P2X₂and P2X₃receptors in pO₂detection in pulmonary NEBs (W. Rong et al., J Neurosci (2003) 23(36):11315-21).

There is accordingly a need for compounds that act as modulators of P2X receptors, including antagonists of P2X₃and P2X_2/3receptors, as well as a need for methods of treating diseases, conditions and disorders mediated by P2X₃and/or P2X_2/3receptors. The present invention satisfies these needs as well as others.

SUMMARY OF THE INVENTION

The invention provides compounds of the formula (I):

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or a pharmaceutically acceptable salt thereof,

wherein:

R¹is optionally substituted tetrazolyl;

R²is optionally substituted phenyl, optionally substituted pyridinyl, optionally substituted pyrimidinyl, optionally substituted pyridazinyl or optionally substituted thiophenyl;

R³is:

- hydrogen;
- C_1-6alkyl;
- hetero-C_1-6alkyl; or
- cyano;

R⁴is:

- hydrogen;
- C_1-6alkyl; or
- hetero-C_1-6alkyl;

or R³and R⁴together with the atom to which they are attached may form a C_3-6carbocyclic ring;

R⁵is:

- C_1-6alkyl;
- hetero-C_1-6alkyl;
- halo-C_1-6alkyl;
- N—C_1-6alkylamino;
- N,N-di-(C_1-6alkyl)-amino;
- C_3-7cycloalkyl;
- aryl;
- heteroaryl;
- heterocyclyl;
- C_3-7cycloalkyl-C_1-6alkyl;
- heteroaryl-C_1-6alkyl;
- heterocyclyl-C_1-6alkyl;
- aryloxy-C_1-6alkyl;
- —(CR^aR^b)_m—C(O)—R⁸wherein:
  - m is 0 or 1;
  - R^aand R^beach independently is:
    - hydrogen; or
    - C_1-6alkyl; and
  - R⁸is:
    - hydrogen;
    - C_1-6alkyl;
    - hetero-C_1-6alkyl;
    - C_3-7cycloalkyl;
    - aryl;
    - heteroaryl;
    - heterocyclyl;
    - C_3-7cycloalkyl-C_1-6alkyl;
    - aryl-C_1-6alkyl;
    - heteroaryl-C_1-6alkyl;
    - heterocyclyl-C_1-6alkyl;
    - C_3-7cycloalkyloxy;
    - aryloxy;
    - heteroaryloxy;
    - heterocyclyloxy;
    - C_3-7cycloalkyloxy-C_1-6alkyl;
    - aryloxy-C_1-6alkyl;
    - heteroaryloxy-C_1-6alkyl;
    - heterocyclyloxy-C_1-6alkyl; or
    - —NR⁹R¹⁰, wherein:
      - R⁹is:
      - hydrogen; or
      - C_1-6alkyl; and
      - R¹⁰is:
      - hydrogen;
      - C_1-6alkyl;
      - hetero-C_1-6alkyl;
      - C_3-7cycloalkyl;
      - aryl;
      - heteroaryl;
      - heterocyclyl;
      - C_3-7cycloalkyl-C_1-6alkyl;
      - aryl-C_1-6alkyl;
      - heteroaryl-C_1-6alkyl; or
      - heterocyclyl-C_1-6alkyl; and

or R⁴and R⁵together with the atom to which they are attached may form a C_3-6carbocyclic ring that is optionally substituted with hydroxy;

or R⁴and R⁵together with the atom to which they are attached may form a C_4-6heterocyclic ring containing one or two heteroatoms each independently selected from O, N and S;

or R³, R⁴and R⁵together with the atom to which they are attached may form a six-membered heteroaryl containing one or two nitrogen atoms, and which is optionally substituted with halo, amino or C_1-6alkyl;

R⁶is:

- C_1-6alkyl;
- C_1-6alkyloxy;
- halo;
- C_1-6haloalkyl; or
- cyano;

provided that when R¹is tetrazol-1-yl, R²is 4-methyl-phenyl, R³is methyl, R⁴is hydrogen and R⁶is hydrogen, then R⁵is not furan-2-yl.

The invention also provides and pharmaceutical compositions comprising the compounds, methods of using the compounds, and methods of preparing the compounds.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Unless otherwise stated, the following terms used in this Application, including the specification and claims, have the definitions given below. It must be noted that, as used in the specification and the appended claims, the singular forms “a”, “an,” and “the” include plural referents unless the context clearly dictates otherwise.

“Agonist” refers to a compound that enhances the activity of another compound or receptor site.

“Alkyl” means the monovalent linear or branched saturated hydrocarbon moiety, consisting solely of carbon and hydrogen atoms, having from one to twelve carbon atoms. “Lower alkyl” refers to an alkyl group of one to six carbon atoms, i.e. C₁-C₆alkyl. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, isobutyl, sec-butyl, tert-butyl, pentyl, n-hexyl, octyl, dodecyl, and the like.

“Alkenyl” means a linear monovalent hydrocarbon radical of two to six carbon atoms or a branched monovalent hydrocarbon radical of three to six carbon atoms, containing at least one double bond, e.g., ethenyl, propenyl, and the like.

“Alkynyl” means a linear monovalent hydrocarbon radical of two to six carbon atoms or a branched monovalent hydrocarbon radical of three to six carbon atoms, containing at least one triple bond, e.g., ethynyl, propynyl, and the like.

“Alkylene” means a linear saturated divalent hydrocarbon radical of one to six carbon atoms or a branched saturated divalent hydrocarbon radical of three to six carbon atoms, e.g., methylene, ethylene, 2,2-dimethylethylene, propylene, 2-methylpropylene, butylene, pentylene, and the like.

“Alkoxy” and “alkyloxy”, which may be used interchangeably, mean a moiety of the formula —OR, wherein R is an alkyl moiety as defined herein. Examples of alkoxy moieties include, but are not limited to, methoxy, ethoxy, isopropoxy, and the like.

“Alkoxyalkyl” means a moiety of the formula R^a—O—R^b—, where R^ais alkyl and R^bis alkylene as defined herein. Exemplary alkoxyalkyl groups include, by way of example, 2-methoxyethyl, 3-methoxypropyl, 1-methyl-2-methoxyethyl, 1-(2-methoxyethyl)-3-methoxypropyl, and 1-(2-methoxyethyl)-3-methoxypropyl.

“Alkylcarbonyl” means a moiety of the formula —R′—R″, where R′ is oxo and R″ is alkyl as defined herein.

“Alkylsulfonyl” means a moiety of the formula —R′—R″, where R′ is —SO₂— and R″ is alkyl as defined herein.

“Alkylsulfonylalkyl means a moiety of the formula —R′—R″—R′″ where where R′ is alkylene, R″ is —SO₂— and R′″ is alkyl as defined herein.

“Alkylamino means a moiety of the formula —NR—R′ wherein R is hydrogen or alkyl and R′ is alkyl as defined herein.

“Alkoxyamino” means a moiety of the formula —NR—OR′ wherein R is hydrogen or alkyl and R′ is alkyl as defined herein.

“Alkylsulfanyl” means a moiety of the formula —SR wherein R is alkyl as defined herein.

“Aminoalkyl” means a group —R—R′ wherein R′ is amino and R is alkylene as defined herein. “Aminoalkyl” includes aminomethyl, aminoethyl, 1-aminopropyl, 2-aminopropyl, and the like. The amino moiety of “aminoalkyl” may be substituted once or twice with alkyl to provide “alkylaminoalkyl” and “dialkylaminoalkyl” respectively. “Alkylaminoalkyl” includes methylaminomethyl, methylaminoethyl, methylaminopropyl, ethylaminoethyl and the like. “Dialkylaminoalkyl” includes dimethylaminomethyl, dimethylaminoethyl, dimethylaminopropyl, N-methyl-N-ethylaminoethyl, and the like.

“Aminoalkoxy” means a group —OR—R′ wherein R′ is amino and R is alkylene as defined herein.

“Alkylsulfonylamido” means a moiety of the formula —NR′SO₂—R wherein R is alkyl and R′ is hydrogen or alkyl.

“Aminocarbonyloxyalkyl” or “carbamylalkyl” means a group of the formula —R—O—C(O)— NR′R″ wherein R is alkylene and R′, R″ each independently is hydrogen or alkyl as defined herein.

“Alkynylalkoxy” means a group of the formula —O—R—R′ wherein R is alkylene and R′ is alkynyl as defined herein.

“Antagonist” refers to a compound that diminishes or prevents the action of another compound or receptor site.

“Aryl” means a monovalent cyclic aromatic hydrocarbon moiety consisting of a mono-, bi- or tricyclic aromatic ring. The aryl group can be optionally substituted as defined herein. Examples of aryl moieties include, but are not limited to, optionally substituted phenyl, naphthyl, phenanthryl, fluorenyl, indenyl, pentalenyl, azulenyl, oxydiphenyl, biphenyl, methylenediphenyl, aminodiphenyl, diphenylsulfidyl, diphenylsulfonyl, diphenylisopropylidenyl, benzodioxanyl, benzofuranyl, benzodioxylyl, benzopyranyl, benzoxazinyl, benzoxazinonyl, benzopiperadinyl, benzopiperazinyl, benzopyrrolidinyl, benzomorpholinyl, methylenedioxyphenyl, ethylenedioxyphenyl, and the like, including partially hydrogenated derivatives thereof.

“Arylalkyl” and “Aralkyl”, which may be used interchangeably, mean a radical—R^aR^bwhere R^ais an alkylene group and R^bis an aryl group as defined herein; e.g., phenylalkyls such as benzyl, phenylethyl, 3-(3-chlorophenyl)-2-methylpentyl, and the like are examples of arylalkyl.

“Arylsulfonyl means a group of the formula —SO₂—R wherein R is aryl as defined herein.

“Aryloxy” means a group of the formula —O—R wherein R is aryl as defined herein.

“Aralkyloxy” means a group of the formula —O—R—R″ wherein R is alkylene and R′ is aryl as defined herein.

“Cyanoalkyl” means a moiety of the formula —R′—R″, where R′ is alkylene as defined herein and R″ is cyano or nitrile.

“Cycloalkyl” means a monovalent saturated carbocyclic moiety consisting of mono- or bicyclic rings. Cycloalkyl can optionally be substituted with one or more substituents, wherein each substituent is independently hydroxy, alkyl, alkoxy, halo, haloalkyl, amino, monoalkylamino, or dialkylamino, unless otherwise specifically indicated. Examples of cycloalkyl moieties include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like, including partially unsaturated derivatives thereof.

“Cycloalkylalkyl” means a moiety of the formula —R′—R″, where R′ is alkylene and R″ is cycloalkyl as defined herein.

“Heteroalkyl” means an alkyl radical as defined herein wherein one, two or three hydrogen atoms have been replaced with a substituent independently selected from the group consisting of —OR^a, —NR^bR^c, and —S(O)_nR^d(where n is an integer from 0 to 2), with the understanding that the point of attachment of the heteroalkyl radical is through a carbon atom, wherein R^ais hydrogen, acyl, alkyl, cycloalkyl, or cycloalkylalkyl; R^band R^care independently of each other hydrogen, acyl, alkyl, cycloalkyl, or cycloalkylalkyl; and when n is 0, R^dis hydrogen, alkyl, cycloalkyl, or cycloalkylalkyl, and when n is 1 or 2, R^dis alkyl, cycloalkyl, cycloalkylalkyl, amino, acylamino, monoalkylamino, or dialkylamino. Representative examples include, but are not limited to, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxy-1-hydroxymethylethyl, 2,3-dihydroxypropyl, 1-hydroxymethylethyl, 3-hydroxybutyl, 2,3-dihydroxybutyl, 2-hydroxy-1-methylpropyl, 2-aminoethyl, 3-aminopropyl, 2-methylsulfonylethyl, aminosulfonylmethyl, aminosulfonylethyl, aminosulfonylpropyl, methylaminosulfonylmethyl, methylaminosulfonylethyl, methylaminosulfonylpropyl, and the like.

“Heteroaryl” means a monocyclic or bicyclic radical of 5 to 12 ring atoms having at least one aromatic ring containing one, two, or three ring heteroatoms selected from N, O, or S, the remaining ring atoms being C, with the understanding that the attachment point of the heteroaryl radical will be on an aromatic ring. The heteroaryl ring may be optionally substituted as defined herein. Examples of heteroaryl moieties include, but are not limited to, optionally substituted imidazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, pyrazinyl, thienyl, benzothienyl, thiophenyl, furanyl, pyranyl, pyridyl, pyrrolyl, pyrazolyl, pyrimidyl, quinolinyl, isoquinolinyl, benzofuryl, benzothiophenyl, benzothiopyranyl, benzimidazolyl, benzooxazolyl, benzooxadiazolyl, benzothiazolyl, benzothiadiazolyl, benzopyranyl, indolyl, isoindolyl, triazolyl, triazinyl, quinoxalinyl, purinyl, quinazolinyl, quinolizinyl, naphthyridinyl, pteridinyl, carbazolyl, azepinyl, diazepinyl, acridinyl and the like, including partially hydrogenated derivatives thereof.

Heteroarylalkyl” or “heteroaralkyl” means a group of the formula —R—R′ wherein R is alkylene and R′ is heteroaryl as defined herein.

“Heteroarylsulfonyl means a group of the formula —SO₂—R wherein R is heteroaryl as defined herein.

“Heteroaryloxy” means a group of the formula —O—R wherein R is heteroaryl as defined herein.

“Heteroaralkyloxy” means a group of the formula —O—R—R″ wherein R is alkylene and R′ is heteroaryl as defined herein.

The terms “halo”, “halogen” and “halide”, which may be used interchangeably, refer to a substituent fluoro, chloro, bromo, or iodo.

“Haloalkyl” means alkyl as defined herein in which one or more hydrogen has been replaced with same or different halogen. Exemplary haloalkyls include —CH₂Cl, —CH₂CF₃, —CH₂CCl₃, perfluoroalkyl (e.g., —CF₃), and the like.

“Haloalkoxy” means a moiety of the formula —OR, wherein R is a haloalkyl moiety as defined herein. An exemplary haloalkoxy is difluoromethoxy.

“Heterocycloamino” means a saturated ring wherein at least one ring atom is N, NH or N-alkyl and the remaining ring atoms form an alkylene group.

“Heterocyclyl” means a monovalent saturated moiety, consisting of one to three rings, incorporating one, two, or three or four heteroatoms (chosen from nitrogen, oxygen or sulfur). The heterocyclyl ring may be optionally substituted as defined herein. Examples of heterocyclyl moieties include, but are not limited to, optionally substituted piperidinyl, piperazinyl, homopiperazinyl, azepinyl, pyrrolidinyl, pyrazolidinyl, imidazolinyl, imidazolidinyl, pyridinyl, pyridazinyl, pyrimidinyl, oxazolidinyl, isoxazolidinyl, morpholinyl, thiazolidinyl, isothiazolidinyl, quinuclidinyl, quinolinyl, isoquinolinyl, benzimidazolyl, thiadiazolylidinyl, benzothiazolidinyl, benzoazolylidinyl, dihydrofuryl, tetrahydrofuryl, dihydropyranyl, tetrahydropyranyl, thiamorpholinyl, thiamorpholinylsulfoxide, thiamorpholinylsulfone, dihydroquinolinyl, dihydrisoquinolinyl, tetrahydroquinolinyl, tetrahydrisoquinolinyl, and the like.

“Heterocyclylalkyl” means a moiety of the formula —R—R′ wherein R is alkylene and R′ is heterocyclyl as defined herein.

“Heterocyclyloxy” means a moiety of the formula —OR wherein R is heterocyclyl as defined herein.

“Heterocyclylalkoxy” means a moiety of the formula —OR—R′ wherein R is alkylene and R′ is heterocyclyl as defined herein.

“Hydroxyalkoxy” means a moiety of the formula —OR wherein R is hydroxyalkyl as defined herein.

“Hydroxyalkylamino” means a moiety of the formula —NR—R′ wherein R is hydrogen or alkyl and R′ is hydroxyalkyl as defined herein.

“Hydroxyalkylaminoalkyl” means a moiety of the formula —R—NR′—R″ wherein R is alkylene, R′ is hydrogen or alkyl, and R″ is hydroxyalkyl as defined herein.

“Hydroxycarbonylalkyl” or “carboxyalkyl” means a group of the formula —R—(CO)—OH where R is alkylene as defined herein.

“Hydroxyalkyloxycarbonylalkyl” or “hydroxyalkoxycarbonylalkyl” means a group of the formula —R—C(O)—O—R—OH wherein each R is alkylene and may be the same or different.

“Hydroxyalkyl” means an alkyl moiety as defined herein, substituted with one or more, preferably one, two or three hydroxy groups, provided that the same carbon atom does not carry more than one hydroxy group. Representative examples include, but are not limited to, hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 2-hydroxy-1-hydroxymethylethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl and 2-(hydroxymethyl)-3-hydroxypropyl

“Hydroxycycloalkyl” means a cycloalkyl moiety as defined herein wherein one, two or three hydrogen atoms in the cycloalkyl radical have been replaced with a hydroxy substituent. Representative examples include, but are not limited to, 2-, 3-, or 4-hydroxycyclohexyl, and the like.

“Urea” or “ureido” means a group of the formula —NR′—C(O)—NR″R′″ wherein R′, R″ and R′″ each independently is hydrogen or alkyl.

“Carbamate” means a group of the formula —O—C(O)—NR′R″ wherein R′ and R″ each independently is hydrogen or alkyl.

“Carboxy” means a group of the formula —O—C(O)—OH.

“Sulfonamido” means a group of the formula —SO₂—NR′R″ wherein R′, R″ and R′″ each independently is hydrogen or alkyl.

“Optionally substituted”, when used in association with “aryl”, phenyl”, “heteroaryl” “cycloalkyl” or “heterocyclyl”, means an aryl, phenyl, heteroaryl, cyclohexyl or heterocyclyl which is optionally substituted independently with one to four substituents, preferably one or two substituents selected from alkyl, cycloalkyl, cycloalkylalkyl, heteroalkyl, hydroxyalkyl, halo, nitro, cyano, hydroxy, alkoxy, amino, acylamino, mono-alkylamino, di-alkylamino, haloalkyl, haloalkoxy, heteroalkyl, —COR (where R is hydrogen, alkyl, phenyl or phenylalkyl), —(CR′R″)_n—COOR (where n is an integer from 0 to 5, R′ and R″ are independently hydrogen or alkyl, and R is hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl), or —(CR′R″)_n—CONR^aR^b(where n is an integer from 0 to 5, R′ and R″ are independently hydrogen or alkyl, and R^aand R^bare, independently of each other, hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl). Certain preferred optional substituents for “aryl”, phenyl”, “heteroaryl” “cycloalkyl” or “heterocyclyl” include alkyl, halo, haloalkyl, alkoxy, cyano, amino and alkylsulfonyl. More preferred substituents are methyl, fluoro, chloro, trifluoromethyl, methoxy, amino and methanesulfonyl.

“Leaving group” means the group with the meaning conventionally associated with it in synthetic organic chemistry, i.e., an atom or group displaceable under substitution reaction conditions. Examples of leaving groups include, but are not limited to, halogen, alkane- or arylenesulfonyloxy, such as methanesulfonyloxy, ethanesulfonyloxy, thiomethyl, benzenesulfonyloxy, tosyloxy, and thienyloxy, dihalophosphinoyloxy, optionally substituted benzyloxy, isopropyloxy, acyloxy, and the like.

“Modulator” means a molecule that interacts with a target. The interactions include, but are not limited to, agonist, antagonist, and the like, as defined herein.

“Optional” or “optionally” means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not.

“Disease” and “Disease state” means any disease, condition, symptom, disorder or indication.

“Inert organic solvent” or “inert solvent” means the solvent is inert under the conditions of the reaction being described in conjunction therewith, including for example, benzene, toluene, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, chloroform, methylene chloride or dichloromethane, dichloroethane, diethyl ether, ethyl acetate, acetone, methyl ethyl ketone, methanol, ethanol, propanol, isopropanol, tert-butanol, dioxane, pyridine, and the like. Unless specified to the contrary, the solvents used in the reactions of the present invention are inert solvents.

“Pharmaceutically acceptable” means that which is useful in preparing a pharmaceutical composition that is generally safe, non-toxic, and neither biologically nor otherwise undesirable and includes that which is acceptable for veterinary as well as human pharmaceutical use.

“Pharmaceutically acceptable salts” of a compound means salts that are pharmaceutically acceptable, as defined herein, and that possess the desired pharmacological activity of the parent compound. Such salts include:

- acid addition salts formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like; or formed with organic acids such as acetic acid, benzenesulfonic acid, benzoic, camphorsulfonic acid, citric acid, ethanesulfonic acid, fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, glycolic acid, hydroxynaphtoic acid, 2-hydroxyethanesulfonic acid, lactic acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, muconic acid, 2-naphthalenesulfonic acid, propionic acid, salicylic acid, succinic acid, tartaric acid, p-toluenesulfonic acid, trimethylacetic acid, and the like; or
- salts formed when an acidic proton present in the parent compound either is replaced by a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or an aluminum ion; or coordinates with an organic or inorganic base. Acceptable organic bases include diethanolamine, ethanolamine, N-methylglucamine, triethanolamine, tromethamine, and the like. Acceptable inorganic bases include aluminum hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate and sodium hydroxide.

The preferred pharmaceutically acceptable salts are the salts formed from acetic acid, hydrochloric acid, sulphuric acid, methanesulfonic acid, maleic acid, phosphoric acid, tartaric acid, citric acid, sodium, potassium, calcium, zinc, and magnesium.

It should be understood that all references to pharmaceutically acceptable salts include solvent addition forms (solvates) or crystal forms (polymorphs) as defined herein, of the same acid addition salt.

“Protective group” or “protecting group” means the group which selectively blocks one reactive site in a multifunctional compound such that a chemical reaction can be carried out selectively at another unprotected reactive site in the meaning conventionally associated with it in synthetic chemistry. Certain processes of this invention rely upon the protective groups to block reactive nitrogen and/or oxygen atoms present in the reactants. For example, the terms “amino-protecting group” and “nitrogen protecting group” are used interchangeably herein and refer to those organic groups intended to protect the nitrogen atom against undesirable reactions during synthetic procedures. Exemplary nitrogen protecting groups include, but are not limited to, trifluoroacetyl, acetamido, benzyl (Bn), benzyloxycarbonyl (carbobenzyloxy, CBZ), p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl, tert-butoxycarbonyl (BOC), and the like. The artisan in the art will know how to chose a group for the ease of removal and for the ability to withstand the following reactions.

“Solvates” means solvent additions forms that contain either stoichiometric or non stoichiometric amounts of solvent. Some compounds have a tendency to trap a fixed molar ratio of solvent molecules in the crystalline solid state, thus forming a solvate. If the solvent is water the solvate formed is a hydrate, when the solvent is alcohol, the solvate formed is an alcoholate. Hydrates are formed by the combination of one or more molecules of water with one of the substances in which the water retains its molecular state as H₂O, such combination being able to form one or more hydrate.

“Subject” means mammals and non-mammals. Mammals means any member of the mammalia class including, but not limited to, humans; non-human primates such as chimpanzees and other apes and monkey species; farm animals such as cattle, horses, sheep, goats, and swine; domestic animals such as rabbits, dogs, and cats; laboratory animals including rodents, such as rats, mice, and guinea pigs; and the like. Examples of non-mammals include, but are not limited to, birds, and the like. The term “subject” does not denote a particular age or sex.

“Disorders of the urinary tract” or “uropathy” used interchangeably with “symptoms of the urinary tract” means the pathologic changes in the urinary tract. Examples of urinary tract disorders include, but are not limited to, incontinence, benign prostatic hypertrophy (BPH), prostatitis, detrusor hyperreflexia, outlet obstruction, urinary frequency, nocturia, urinary urgency, overactive bladder, pelvic hypersensitivity, urge incontinence, urethritis, prostatodynia, cystitis, idiophatic bladder hypersensitivity, and the like.

“Disease states associated with the urinary tract” or “urinary tract disease states” or “uropathy” used interchangeably with “symptoms of the urinary tract” mean the pathologic changes in the urinary tract, or dysfunction of urinary bladder smooth muscle or its innervation causing disordered urinary storage or voiding. Symptoms of the urinary tract include, but are not limited to, overactive bladder (also known as detrusor hyperactivity), outlet obstruction, outlet insufficiency, and pelvic hypersensitivity.

“Overactive bladder” or “detrusor hyperactivity” includes, but is not limited to, the changes symptomatically manifested as urgency, frequency, altered bladder capacity, incontinence, micturition threshold, unstable bladder contractions, sphincteric spasticity, detrusor hyperreflexia (neurogenic bladder), detrusor instability, and the like.

“Outlet obstruction” includes, but is not limited to, benign prostatic hypertrophy (BPH), urethral stricture disease, tumors, low flow rates, difficulty in initiating urination, urgency, suprapubic pain, and the like.

“Outlet insufficiency” includes, but is not limited to, urethral hypermobility, intrinsic sphincteric deficiency, mixed incontinence, stress incontinence, and the like.

“Pelvic Hypersensitivity” includes, but is not limited to, pelvic pain, interstitial (cell) cystitis, prostatodynia, prostatitis, vulvadynia, urethritis, orchidalgia, overactive bladder, and the like.

“Respiratory disorder” refers to, without limitation, chronic obstructive pulmonary disease (COPD), asthma, bronchospasm, and the like.

“Gastrointestinal disorder” (“GI disorder”) refers to, without limitation, Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), biliary colic and other biliary disorders, renal colic, diarrhea-dominant IBS, pain associated with GI distension, and the like.

“Pain” includes, without limitation, inflammatory pain; surgical pain; visceral pain; dental pain; premenstrual pain; central pain; pain due to burns; migraine or cluster headaches; nerve injury; neuritis; neuralgias; poisoning; ischemic injury; interstitial cystitis; cancer pain; viral, parasitic or bacterial infection; post-traumatic injury; or pain associated with irritable bowel syndrome.

“Therapeutically effective amount” means an amount of a compound that, when administered to a subject for treating a disease state, is sufficient to effect such treatment for the disease state. The “therapeutically effective amount” will vary depending on the compound, disease state being treated, the severity or the disease treated, the age and relative health of the subject, the route and form of administration, the judgment of the attending medical or veterinary practitioner, and other factors.

The terms “those defined above” and “those defined herein” when referring to a variable incorporates by reference the broad definition of the variable as well as preferred, more preferred and most preferred definitions, if any.

“Treating” or “treatment” of a disease state includes:

- (i) preventing the disease state, i.e. causing the clinical symptoms of the disease state not to develop in a subject that may be exposed to or predisposed to the disease state, but does not yet experience or display symptoms of the disease state.
- (ii) inhibiting the disease state, i.e., arresting the development of the disease state or its clinical symptoms, or
- (iii) relieving the disease state, i.e., causing temporary or permanent regression of the disease state or its clinical symptoms.

The terms “treating”, “contacting” and “reacting” when referring to a chemical reaction means adding or mixing two or more reagents under appropriate conditions to produce the indicated and/or the desired product. It should be appreciated that the reaction which produces the indicated and/or the desired product may not necessarily result directly from the combination of two reagents which were initially added, i.e., there may be one or more intermediates which are produced in the mixture which ultimately leads to the formation of the indicated and/or the desired product.

Nomenclature and Structures

In general, the nomenclature used in this Application is based on AUTONOMY™ v.4.0, a Beilstein Institute computerized system for the generation of IUPAC systematic nomenclature. Chemical structures shown herein were prepared using ISIS® version 2.2. Any open valency appearing on a carbon, oxygen or nitrogen atom in the structures herein indicates the presence of a hydrogen atom. Where a chiral center exists in a structure but no specific stereochemistry is shown for the chiral center, both enantiomers associated with the chiral structure are encompassed by the structure.

All patents and publications identified herein are incorporated herein by reference in their entirety.

Compounds of the Invention

The invention provides compounds of the formula I:

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or a pharmaceutically acceptable salt thereof,

wherein:

R¹is optionally substituted tetrazolyl;

R²is optionally substituted phenyl, optionally substituted pyridinyl, optionally substituted pyrimidinyl, optionally substituted pyridazinyl or optionally substituted thiophenyl;

R³is:

- hydrogen;
- C_1-6alkyl;
- hetero-C_1-6alkyl; or
- cyano;

R⁴is:

- hydrogen;
- C_1-6alkyl; or
- hetero-C_1-6alkyl;

or R³and R⁴together with the atom to which they are attached may form a C_3-6carbocyclic ring;

R⁵is:

- C_1-6alkyl;
- hetero-C_1-6alkyl;
- halo-C_1-6alkyl;
- N—C_1-6alkylamino;
- N,N-di-(C_1-6alkyl)-amino;
- C_3-7cycloalkyl;
- aryl;
- heteroaryl;
- heterocyclyl;
- C_3-7cycloalkyl-C_1-6alkyl;
- heteroaryl-C_1-6alkyl;
- heterocyclyl-C_1-6alkyl;
- aryloxy-C_1-6alkyl;
- —(CR^aR^b)_m—C(O)—R⁸wherein:
  - m is 0 or 1;
  - R^aand R^beach independently is:
    - hydrogen; or
    - C_1-6alkyl; and
  - R⁸is:
    - hydrogen;
    - C_1-6alkyl;
    - hetero-C_1-6alkyl;
    - C_3-7cycloalkyl;
    - aryl;
    - heteroaryl;
    - heterocyclyl;
    - C_3-7cycloalkyl-C_1-6alkyl;
    - aryl-C_1-6alkyl;
    - heteroaryl-C_1-6alkyl;
    - heterocyclyl-C_1-6alkyl;
    - C_3-7cycloalkyloxy;
    - aryloxy;
    - heteroaryloxy;
    - heterocyclyloxy;
    - C_3-7cycloalkyloxy-C_1-6alkyl;
    - aryloxy-C_1-6alkyl;
    - heteroaryloxy-C_1-6alkyl;
    - heterocyclyloxy-C_1-6alkyl; or
    - —NR⁹R¹⁰, wherein:
      - R⁹is:
      - hydrogen; or
      - C_1-6alkyl; and
      - R¹⁰is:
      - hydrogen;
      - C_1-6alkyl;
      - hetero-C_1-6alkyl;
      - C_3-7cycloalkyl;
      - aryl;
      - heteroaryl;
      - heterocyclyl;
      - C_3-7cycloalkyl-C_1-6alkyl;
      - aryl-C_1-6alkyl;
      - heteroaryl-C_1-6alkyl; or
      - heterocyclyl-C_1-6alkyl; and

or R⁴and R⁵together with the atom to which they are attached may form a C_3-6carbocyclic ring that is optionally substituted with hydroxy;

or R⁴and R⁵together with the atom to which they are attached may form a C_4-6heterocyclic ring containing one or two heteroatoms each independently selected from O, N and S;

R⁶is:

- C_1-6alkyl;
- C_1-6alkyloxy;
- halo;
- C_1-6haloalkyl; or
- cyano;

provided that when R¹is tetrazol-1-yl, R²is 4-methyl-phenyl, R³is methyl, R⁴is hydrogen and R⁶is hydrogen, then R⁵is not furan-2-yl.

In many embodiments of formula I, R²is optionally substituted phenyl, such as phenyl optionally substituted once, twice or three times, preferably once or twice, with any of C_1-6alkyl, C_1-6alkyloxy, halo, C_1-6haloalkyl, hetero-C_1-6alkyl, C_1-6alkylsulfonyl or cyano.

In certain embodiments R²is phenyl substituted once or twice with halo or methyl.

In many embodiments of formula I, R²is phenyl substituted at the 4-position with methyl or halo and optionally substituted at the 2- and 6-positions with halo.

In many embodiments of formula I, R²is phenyl substituted at the 4-position with methyl or halo and optionally substituted at the 2-position with halo.

In certain embodiments of formula I, R²is 4-methyl-phenyl, 2-fluoro-4-methyl-phenyl, 2-chloro-4-fluoro-phenyl, 4-chloro-2-fluoro-phenyl, 2,4-dichloro-phenyl, 2,4-difluoro-phenyl, or 2-chloro-4-methyl-phenyl.

In certain embodiments of formula I, R²is 4-methyl-phenyl or 4-chloro-phenyl.

In certain embodiments of formula I, R²is 4-methyl-phenyl.

In certain embodiments of formula I, R²is 2-fluoro-4-methyl-phenyl.

In certain embodiments of formula I, R²is 2-chloro-4-fluoro-phenyl.

In certain embodiments of formula I, R²is 4-chloro-2-fluoro-phenyl.

In certain embodiments of formula I, R²is 2,4-dichloro-phenyl.

In certain embodiments of formula I, R²is 2,4-difluoro-phenyl.

In certain embodiments of formula I, R²is 2-chloro-4-methyl-phenyl.

In many embodiments of formula I, R²is optionally substituted pyridinyl. Exemplary pyridinyl include pyridin-2-yl, and pyridin-2-one-1-yl, each optionally substituted once, twice or three times, preferably once or twice, with any of C_1-6alkyl, C_1-6alkyloxy, halo, C_1-6haloalkyl, hetero-C_1-6alkyl, C_1-6alkylsulfonyl or cyano. Preferred pyridyl include 4-methyl-pyridin-2-yl, 4-fluoro-pyridin-2-yl and 4-methyl-pyridin-2-one-1-yl.

In certain embodiments of formula I, R²is pyridin 2-yl substituted with methyl or halo at the 5-position.

In certain embodiments of formula I, R²is pyridin 2-yl substituted with methyl or halo at the 5-position and optionally substituted with halo at the 3-position.

In certain embodiments of formula I, R²is 5-methyl-pyridin-2-yl, 5-chloro-pyridin-2-yl, 5-fluoro-pyridin-2-yl, 5-methyl-3-fluoro-pyridin-2-yl, 5-methyl-3-chloro-pyridin-2-yl, 3,5-difluoro-pyridin-2-yl or 3,5-dichloro-pyridin-2-yl.

In certain embodiments of formula I, R²is 5-methyl-pyridin-2-yl.

In certain embodiments of formula I, R²is 5-chloro-pyridin-2-yl.

In certain embodiments of formula I, R²is 5-fluoro-pyridin-2-yl.

In certain embodiments of formula I, R²is 5-methyl-3-fluoro-pyridin-2-yl.

In certain embodiments of formula I, R²is 5-methyl-3-chloro-pyridin-2-yl.

In certain embodiments of formula I, R²is 3,5-difluoro-pyridin-2-yl.

In certain embodiments of formula I, R²is 3,5-dichloro-pyridin-2-yl.

In certain embodiments of formula I, R²is optionally substituted pyridazinyl. In such embodiments R²may be 6-chloro-pyridazinyl or 6-methyl-pyridazinyl, preferably 6-chloro-pyridazinyl.

In certain embodiments of formula I, R²is optionally substituted thiophenyl. In such embodiments R²may be thiophen-2-yl optionally substituted with C_1-6alkyl or halo. Preferred thiophenyl include 3-methyl-thiophen-2-yl, 5-methyl-thiophen-2-yl and 5-chloro-thiophen-2-yl.

In many embodiments of formula I, R⁶is hydrogen. In certain embodiments of formula I, R⁶may be methyl.

In many embodiments of formula I, R³is hydrogen.

In many embodiments of formula I, R³is C_1-6alkyl. A preferred C_1-6alkyl in such embodiments is methyl.

In many embodiments of formula I, R⁴is C_1-6alkyl. A preferred C_1-6alkyl in such embodiments is methyl.

In many embodiments of formula I, R³is hydrogen and R⁴is C_1-6alkyl, preferably methyl.

In certain embodiments of formula I, R³and R⁴are hydrogen.

In certain embodiments of formula I, R³and R⁴together with the atom to which they are attached may form a C_3-6carbocyclic ring.

In certain embodiments of formula I, R³and R⁴together with the atom to which they are attached may form a cyclopropyl group.

In certain embodiments of formula I, R⁴and R⁵together with the atom to which they are attached form a C_3-6carbocyclic ring that is optionally substituted with hydroxy.

In certain embodiments of formula I, R⁴and R⁵together with the atom to which they are attached form a cyclopropyl.

In certain embodiments of formula I, R³is hydrogen and R⁴and R⁵together with the atom to which they are attached form a cyclopropyl.

In certain embodiments of formula I, R³is hydrogen and R⁴and R⁵together with the atom to which they are attached form a cyclopentyl optionally substituted with hydroxy.

In certain embodiments of formula I, R⁴and R⁵together with the atom to which they are attached form a C_4-6heterocyclic ring containing one or two heteroatoms each independently selected from O, N and S.

In certain embodiments of formula I, R⁴and R⁵together with the atom to which they are attached form a piperidinyl group or oxetanyl ring group.

In certain embodiments of formula I, R⁴and R⁵together with the atom to which they are attached form a piperidin-3-yl group or an oxetan-3-yl group.

In certain embodiments of formula I, R³, R⁴and R⁵together with the atom to which they are attached form a six-membered heteroaryl containing one or two nitrogen atoms, and which is optionally substituted with halo, amino or C_1-6alkyl.

In certain embodiments of formula I, R³, R⁴and R⁵together with the atom to which they are attached form a heteroaryl selected from 2-oxo-1,2-dihydro-pyrimidinyl, pyridinyl, pyrimidinyl, pyridazinyl or pyridazinyl, each optionally substituted with methyl or amino.

In certain embodiments of formula I, R³, R⁴and R⁵together with the atom to which they are attached form a heteroaryl selected from 2-oxo-1,2-dihydro-pyrimidin-4-yl, 2-oxo-1,2-dihydro-pyrimidin-4-yl, 1-methyl-2-oxo-1,2-dihydro-pyrimidin-4-yl, 6-methyl-pyridin-3-yl, pyridazin-4-yl, 6-amino-pyridin-2-yl, 2-aminopyrimidin-4-yl or 2-amino-pyrimidin-3-yl.

In many embodiments of formula I, R¹is tetrazol-1-yl optionally substituted at the 5-position with C_1-6alkyl.

In certain embodiments of formula I, R¹is tetrazol-5-yl optionally substituted at the 1-position with C_1-6alkyl, halo-C_1-6alkyl, hetero-C_1-6alkyl, C_3-6-cycloalkyl, C_3-6cycloalkyl-C_1-6alkyl or cyano. Preferably in such embodiments the 1-position is substituted with C_1-6alkyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl optionally substituted at the 5-position with C_1-6alkyl, halo-C_1-6alkyl, hetero-C_1-6alkyl, C_3-6-cycloalkyl, C_3-6cycloalkyl-C_1-6alkyl or cyano.

In certain embodiments of formula I, R¹is tetrazol-1-yl substituted at the 5-position with C_1-6alkyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl substituted at the 5-position with halo-C_1-4alkyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl substituted at the 5-position with hetero-C_1-6alkyl selected from hydroxy-C_1-6alkyl, C_1-6alkoxy-C_1-6alkyl, C_1-6alkylamino-C_1-6alkyl, or N,N-di-(C_1-6alkyl)-amino-C_1-6alkyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl substituted at the 5-position with halo-C_1-6alkyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl optionally substituted at the 5-position with methyl, ethyl, n-propyl, n-butyl, isopropyl, isobutyl, tert-butyl, cyclopropyl, cyclopropylmethyl, trifluoromethyl, pentafluoro-ethyl, 1,1-difluoro-ethyl, 1-methoxy-ethyl, 1-ethoxy-ethyl, 2-methoxy-1-methyl-ethyl, 1-hydroxy-ethyl, or dimethylamino-methyl.

In certain embodiments of formula I, R¹is tetrazol-1-yl substituted at the 5-position with methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl or cyclopropylmethyl.

In certain embodiments of formula I, R⁵is: C_1-6alkyl; C_1-6alkyloxy-C_1-6alkyl; hydroxy-C_1-6alkyl; C_1-6alkylsulfanyl-C_1-6alkyl; C_1-6alkylsulfonyl-C_1-6alkyl; amino-C_1-6alkyl; N—C_1-6alkyl-amino-C_1-6alkyl; N,N-di-C_1-6alkyl-amino-C_1-6alkyl; C_3-7cycloalkyl; optionally substituted phenyl; heteroaryl, or heterocyclyl-C_1-6alkyl.

In certain embodiments of formula I, R⁵is N—C_1-6alkyl-amino-C_1-6alkyl substituted with halo.

In certain embodiments of formula I, R⁵is: C_1-6alkyloxy-C_1-6alkyl; hydroxy-C_1-6alkyl; heteroaryl, or heterocyclyl-C_1-6alkyl.

In certain embodiments of formula I, R⁵is C_1-6alkyloxy-C_1-6alkyl. One preferred C_1-6alkyloxy-C_1-6alkyl is methoxymethyl.

In certain embodiments of formula I, R⁵is hydroxy-C_1-6alkyl. One preferred hydroxy-C_1-6alkyl is hydroxymethyl.

In certain embodiments of formula I, R⁵is heteroaryl.

In certain embodiments where R⁵is heteroaryl, such heteroaryl may be pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, pyrazolyl, imidazolyl, thienyl, thiazolyl, oxazolyl, isoxazolyl, triazolyl, oxadiazolyl, 3-oxo-2,3-dihydro-isoxazolyl, tetrazolyl, imidazo[2,1-b]thiazolyl, imidazo[1,2-a]pyridinyl, imidazo[4,5-b]pyridinyl, and benzimidazolyl, each of which may be optionally substituted one, two or three times with a group or groups independently selected from C_1-6alkyl, C_1-6alkoxy, C_1-6alkoxy-C_1-6alkyl, halo-C_1-6alkyl, halo, amino, N—C_1-6alkyl-amino, or N,N-di-(C_1-6alkyl)-amino. More preferably, such heteroaryl may be optionally substituted once or twice with a group or groups independently selected from methyl, ethyl, n-propyl, fluoro, chloro, trifluoromethyl, amino, methylamino or dimethylamino.

In certain embodiments where R⁵is heteroaryl, such heteroaryl may be pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, pyrazolyl or thiazolyl, each of which may be optionally substituted once or twice with a group or groups independently selected from methyl, ethyl, n-propyl, fluoro, chloro, amino, methylamino or dimethylamino.

In certain embodiments where R⁵is heteroaryl, such heteroaryl may be pyridinyl, pyrimidinyl, or pyrazinyl, each of which may be optionally substituted once or twice with a group or groups independently selected from methyl, fluoro, chloro, amino, methylamino or dimethylamino.

In certain embodiments of formula I, where R⁵is heteroaryl, such heteroaryl may be thiophen-2-yl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, oxazol-2-yl, pyrimidin-2-yl, pyridazin-4-yl, pyrazin-2-yl, 5-methyl-pyrazin-2-yl, imidazol-1-yl, pyrazol-1-yl, 3,5-dimethyl-pyrazol-1-yl, 2-methyl-thiazol-4-yl, 3-(2-chloro-phenyl)-[1,2,4]-oxadiazol-5-yl, 3-(pyridin-4-yl)-[1,2,4]-oxadiazol-5-yl, pyridazin-3-yl, 2-methyl-pyrazol-3-yl, thiazol-5-yl, 1-methyl-imidazol-2-yl, 6-chloro-pyrimidin-4-yl, 4-ethyl-[1,2,4]-triazol-3-yl, 1,3,5-trimethyl-pyrazol-4-yl, 1,5-dimethyl-pyrazol-4-yl, 1,3-dimethyl-pyrazol-4-yl, 3-(2-methoxy-ethyl)-[1,2,4]-oxadiazol-5-yl, 3-(pyridin-3-yl-[1,2,4]-oxadiazol-5-yl, tetrazol-5-yl, pyrazol-3-yl, 4-amino-2-methyl-pyrimidin-5-yl, 2-amino-pyrimidin-4-yl, 6-methoxy-pyridazin-3-yl, 3-oxo-2,3-dihydro-isoxazol-5-yl, 3-methyl-thiophen-2-yl, 5-methyl-[1,3,4]-oxadizol-2-yl, 4-methyl-isoxazol-3-yl, 3-trifluoromethyl-pyrazol-1-yl, 1-methyl-pyrazol-3-yl, 3-methyl-pyrazol-1-yl, 5-methyl-3-trifluoromethyl-pyrazol-1-yl, 5-cyclopropyl-3-trifluoromethyl-pyrazol-1-yl, imidazo[2,1-b]-thiazol-6-yl, thiazol-4-yl, 2-propyl-pyrazol-3-yl, 2-ethyl-pyrazol-3-yl, 5-amino-pyridazin-2-yl, 3-amino-pyridazin-2-yl, 3-chloro-pyridazin-2-yl, 2-amino-pyrimidin-5-yl, 1-methyl-imidazol-4-yl, 6-amino-pyridin-3-yl, 6-amino-pyridazin-2-yl, 2-amino-pyridin-4-yl, 2-dimethylamino-pyrimidin-5-yl, 6-amino-pyridin-2-yl, 2-methylamino-pyridin-4-yl, 2-dimethylamino-pyridin-4-yl, 3-methyl-2-dimethylamino-pyridin-4-yl, pyrimidin-5-yl, 2-methyl-pyridin-4-yl, 6-methylamino-pyridin-3-yl, 6-dimethylamino-pyridin-3-yl, 6-methylamino-pyrimidin-4-yl, 6-dimethylamino-pyridin-3-yl, 6-methylamino-pyridin-3-yl, 2-methylamino-pyrimidin-5-yl, 6-methyl-pyridin-3-yl, 4-methyl-thiazol-2-yl, 2,6-dimethyl-pyridin-3-yl, imidazo[1,2-a]pyridin-2-yl, 6-methyl-pyridin-2-yl, 1-ethyl-pyrazol-3-yl, 3-methyl-pyridin-2-yl, 4-methyl-thiazol-5-yl, 1-ethyl-imidazol-2-yl, 1-methyl-pyrazol-4-yl, imidazo[4,5-b]pyridin-2-yl, 3,5-difluoro-pyridin-2-yl, 6-fluoro-pyridin-2-yl, 1,5-dimethyl-pyrazol-3-yl, 5-methyl-pyridin-2-yl, 6-trifluoromethyl-pyridin-3-yl, 5-methyl-isoxazol-3-yl, 5-methyl-imidazol-2-yl, 5-methoxy-benzimidazol-2-yl, [1,2,4]triazol-3-yl, and 8-methyl-imidazo[1,2-a]pyridin-2-yl.

In certain embodiments of formula I, R⁵is heterocyclyl-C_1-6alkyl.

In embodiments where R⁵is heterocyclyl-C_1-6alkyl, such heterocyclyl-C_1-6alkyl may be heterocyclyl-methyl such as morpholinomethyl, piperidinyl-methyl, piperazinyl-methyl, thiomorpholinylmethyl, pyrrolidinylmethyl, or azetidinylmethyl, the heterocyclyl portion of each of which may be optionally substituted once or twice with a group or groups independently selected from methyl, methoxy, halo, methanesulfonyl, oxo or acetyl.

In embodiments where R⁵is heterocyclyl-methyl, such heterocyclylmethyl may be morpholin-4-yl-methyl, 4-methanesulfonyl-piperazin-1-yl-methyl, 4-acetyl-piperazin-1-yl-methyl, piperidin-1-yl, thiomorpholin-4-yl-methyl, 4-methyl-piperazin-1-yl-methyl, 3-oxo-piperazin-1-yl-methyl, 3-methoxy-piperidin-1-yl-methyl, 4-methoxy-piperidin-1-yl-methyl, 4-hydroxy-piperidin-1-yl-methyl, 1-oxo-thiomorpholin-4-yl-methyl, 3-hydroxy-pyrrolidin-1-yl-methyl, azetidin-3-yl-methyl, 4-methanesulfonyl-piperidin-1-yl-methyl, 4-fluoro-piperidin1-yl-methyl, 4-acetyl-3-methyl-piperazin-1-yl-methyl, 4-acetyl-3,5-dimethyl-piperazin-1-yl-methyl, 2,6-dimethyl-morpholin-4-yl-methyl, 4,4-difluoro-piperidin1-yl-methyl, 3-fluoro-piperidin1-yl-methyl, 4-methyl-4-hydroxy-piperidin-1-yl-methyl, or 3-fluoro-4-methoxy-piperidin1-yl-methyl.

In certain embodiments of formula I, R⁵is hydroxymethyl, methoxymethyl, pyrazin-2-yl or 5-methyl-pyrazin-2-yl.

In certain embodiments of formula I, R⁵is hydroxymethyl.

In certain embodiments of formula I, R⁵is methoxymethyl.

In certain embodiments of formula I, R⁵is pyrazin-2-yl.

In certain embodiments of formula I, R⁵is 5-methyl-pyrazin-2-yl.