Cox-2 inhibiting pyridine derivatives

This application is a 371 Application of PCT/EP2003/011065, filed 12 Sep. 2003, which claims priority to GB Application Ser. No. 0221443.5 filed 16 Sep. 2002.

This invention relates to pyridine derivatives, to processes for their preparation, to pharmaceutical compositions containing them and to their use in medicine.

The enzyme cyclooxygenase (COX) has recently been discovered to exist in two isoforms, COX-1 and COX-2. COX-1 corresponds to the originally identified constitutive enzyme while COX-2 is rapidly and readily inducible by a number of agents including mitogens, endotoxin, hormones, cytokines and growth factors. Prostaglandins generated by the action of COX have both physiological and pathological roles. It is generally believed that COX-1 is largely responsible for the important physiological functions such as maintenance of gastrointestinal integrity and renal blood flow. In contrast the inducible form, COX-2, is believed to be largely responsible for the pathological effects of prostaglandins where rapid induction of the enzyme occurs in response to such agents as inflammatory agents, hormones, growth factors and cytokines. A selective inhibitor of COX-2 would therefore have anti-inflammatory, anti-pyretic and analgesic properties, without the potential side effects associated with inhibition of COX-1. We have now found a novel group of compounds which are both potent and selective inhibitors of COX-2.

The invention thus provides a compound of formula (I)

or a pharmaceutically acceptable salt thereof in which:

X is selected from the group consisting of oxygen or NR 2 ; Y is selected from the group consisting of CH or nitrogen; R 1 is selected from the group consisting of H, C 1-6 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylOC 1-3 alkyl, C 3-6 alkenyl, C 3-6 alkynyl, C 3-10 cycloalkylC 0-6 alkyl, C 4-7 cycloalkyl substituted by C 1-3 alkyl or C 1-3 alkoxy, C 4-12 bridged cycloalkyl, A(CR 6 R 7 ) n and B(CR 6 R 7 ) n ; R 2 is selected from the group consisting of H and C 1-6 alkyl; or R 1 and R 2 , together with the nitrogen atom to which they are attached form a 4-8 membered saturated heterocyclic ring such as a pyrrolidine, morpholine or piperidine ring, or a 5-membered heteroaryl ring which is unsubstituted or substituted by one R 8 ; R 3 is selected from the group consisting of C 1-5 alkyl and C 1-2 alkyl substituted by one to five fluorine atoms; R 4 is selected from the group consisting of C 1-6 alkyl, NH 2 and R 9 CONH; R 5 is selected from the group consisting of hydrogen, C 1-3 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylO 2 C, halogen, cyano, (C 1-3 alkyl) 2 NCO, C 1-3 alkylS and C 1-3 alkylO 2 S; R 6 and R 7 are independently selected from H or C 1-6 alkyl; A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R 8 ; R 8 is selected from the group consisting of halogen, C 1-6 alkyl, C 1-6 alkyl substituted by one more fluorine atoms, C 1-6 alkoxy, C 1-6 alkoxy substituted by one or more F, NH 2 SO 2 and C 1-6 alkylSO 2 ; B is selected from the group consisting of

where defines the point of attachment of the ring;

R 9 is selected from the group consisting of H, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkylOC 1-6 alkyl, phenyl, HO 2 CC 1-6 alkyl, C 1-6 alkylOCOC 1-6 alkyl, C 1-6 alkylOCO, H 2 NC 1-6 alkyl, C 1-6 alkylOCONHC 1-6 alkyl and C 1-6 alkylCONHC 1-6 alkyl; R 10 is selected from the group consisting of H and halogen; and n is 0 to 4.

The term ‘halogen’ is used to represent fluorine, chlorine, bromine or iodine.

The term ‘alkyl’ as a group or part of a group means a straight or branched chain alkyl group, for example a methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl or t-butyl group.

The term ‘saturated heterocyclic’ means a saturated ring containing at least one atom other than carbon.

The term ‘5-membered heteroaryl’ means a heteroaryl selected from the following:

The term ‘6-membered heteroaryl’ means a heteroaryl selected from the following:

The term ‘6-membered aryl’ means:

It is to be understood that the present invention encompasses all isomers of the compounds of formula (I) and their pharmaceutically acceptable derivatives, including all geometric, tautomeric and optical forms, and mixtures thereof (e.g. racemic mixtures). In particular when the ring B lacks a plane of symmetry the compounds of formula (I) contain a chiral centre as indicated therein by the asterisk *. Furthermore, it will be appreciated by those skilled in the art that when R 6 and R 7 in formula (I) are different the corresponding compounds contain at least one chiral centre, by virtue of the asymmetric carbon atom defined thereby, and that such compounds exist in the form of a pair of optical isomers (i.e. enantiomers).

It will be appreciated that in some instances, compounds of the present invention may include a basic function such as an amino group as a substituent. Such basic functions may be used to form acid addition salts, in particular pharmaceutically acceptable salts. Pharmaceutically acceptable salts include those described by Berge, Bighley, and Monkhouse, J. Pharm. Sci., 1977, 66, 1-19. Such salts may be formed from inorganic and organic acids. Representative examples thereof include maleic, fumaric, benzoic, ascorbic, pamoic, succinic, bismethylenesalicylic, methanesulfonic, ethanedisulfonic, acetic, propionic, tartaric, salicylic, citric, gluconic, aspartic, stearic, palmitic, itaconic, glycolic, p-aminobenzoic, glutamic, taurocholic acid, benzenesulfonic, p-toluenesulfonic, hydrochloric, hydrobromic, sulfuric, cyclohexylsulfamic, phosphoric and nitric acids.

It will be appreciated that in some instances, compounds of the present invention may include a carboxy group as a substituent. Such carboxy groups may be used to form salts, in particular pharmaceutically acceptable salts. Pharmaceutically acceptable salts include those described by Berge, Bighley, and Monkhouse, J. Pharm. Sci., 1977, 66, 1-19. Preferred salts include alkali metal salts such as the sodium and potassium salts.

In one aspect the invention provides a compound of formula (IA)

or a pharmaceutically acceptable salt thereof in which:

X is selected from the group consisting of oxygen or NR 2 ; Y is selected from the group consisting of CH or nitrogen; R 1 is selected from the group consisting of H, C 1-6 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylOC 1-3 alkyl, C 3-6 alkenyl, C 3-6 alkynyl, C 3-10 cycloalkylC 0-6 alkyl, C 4-12 bridged cycloalkyl, A(CR 6 R 7 ) n , and B(CR 6 R 7 ) n ; R 2 is selected from the group consisting of H and C 1-6 alkyl; or R 1 and R 2 , together with the nitrogen atom to which they are attached form a 4-8 membered saturated heterocyclic ring such as a pyrrolidine, morpholine or piperidine ring; R 3 is selected from the group consisting of C 1-5 alkyl and C 1-2 alkyl substituted by one to five fluorine atoms; R 4 is selected from the group consisting of C 1-6 alkyl, NH 2 and R 9 CONH; R 5 is selected from the group consisting of hydrogen, C 1-3 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, halogen, cyano, (C 1-3 alkyl) 2 NCO, C 1-3 alkylS and C 1-3 alkylO 2 S; R 6 and R 7 are independently selected from H or C 1-6 alkyl; A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R 8 ; R 8 is selected from the group consisting of halogen, C 1-6 alkyl, C 1-6 alkyl substituted by one more fluorine atoms, C 1-6 alkoxy, C 1-6 alkoxy substituted by one or more F, NH 2 SO 2 and C 1-6 alkylSO 2 ; B is selected from the group consisting of

where defines the point of attachment of the ring;

R 9 is selected from the group consisting of H, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkylOC 1-6 alkyl, phenyl, HO 2 CC 1-6 alkyl, C 1-6 alkylOCOC 1-6 alkyl, C 1-6 alkylOCO, H 2 NC 1-6 alkyl, C 1-6 alkylOCONHC 1-6 alkyl and C 1-6 alkylCONHC 1-6 alkyl; R 10 is selected from the group consisting of H and halogen; and n is 0 to 4.

In another aspect the invention provides a compound of formula (IB)

or a pharmaceutically acceptable salt thereof, in which all substituents are as for a compound of formula (I) defined hereinabove.

In another aspect the invention provides a compound of formula (IC)

or a pharmaceutically acceptable salt thereof in which:

X is selected from the group consisting of oxygen or NR 2 ; Y is selected from the group consisting of CH or nitrogen; R 1 is selected from the group consisting of H, C 1-6 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylOC 1-3 alkyl, C 3-6 alkenyl, C 3-6 alkynyl, C 3-10 cycloalkylC 0-6 alkyl, C 4-7 cycloalkyl substituted by C 1-3 alkyl or C 1-3 alkoxy, C 4-12 bridged cycloalkyl, A(CR 6 R 7 ) n and B(CR 6 R 7 ) n ; R 2 is selected from the group consisting of H and C 1-6 alkyl; or R 1 and R 2 , together with the nitrogen atom to which they are attached form a 4-8 membered saturated heterocyclic ring such as a pyrrolidine, morpholine or piperidine ring, or a 5-membered heteroaryl ring which is unsubstituted or substituted by one R 8 ; R 3 is selected from the group consisting of C 1-5 alkyl and C 1-2 alkyl substituted by one to five fluorine atoms; R 4 is selected from the group consisting of C 1-6 alkyl, NH 2 and R 9 CONH; R 5 is selected from the group consisting of hydrogen, C 1-3 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylO 2 C, halogen, cyano, (C 1-3 alkyl) 2 NCO, C 1-3 alkylS and C 1-3 alkylO 2 S; R 6 and R 7 are independently selected from H or C 1-6 alkyl; A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R 8 ; R 8 is selected from the group consisting of halogen, C 1-6 alkyl, C 1-6 alkyl substituted by one more fluorine atoms, C 1-6 alkoxy, C 1-6 alkoxy substituted by one or more F, NH 2 SO 2 and C 1-6 alkylSO 2 ; B is selected from the group consisting of

where defines the point of attachment of the ring;

R 9 is selected from the group consisting of H, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkylOC 1-6 alkyl, phenyl, HO 2 CC 1-6 alkyl, C 1-6 alkylOCOC 1-6 alkyl, C 1-6 alkylOCO, H 2 NC 1-6 alkyl, C 1-6 alkylOCONHC 1-6 alkyl and C 1-6 alkylCONHC 1-6 alkyl; R 10 is selected from the group consisting of H and halogen; and n is 1 to 4.

In another aspect of the invention Y is carbon.

In another aspect of the invention R 1 is selected from the group consisting of, C 1-6 alkyl, C 3-10 cycloalkylC 0-6 alkyl, C 5-6 cycloalkyl substituted by C 1-2 alkyl or C 1-2 alkoxy, C 1-3 alkylOC 1-3 alkyl and C 1-2 alkyl substituted by one to five fluorine atoms.

Representative examples of R 1 include cyclohexylmethyl, cyclohexyl, n-butyl, n-pentyl, cyclopentyl, 2-methylpropyl, 2,2-dimethylpropyl, 2,2,2-trifluoroethyl, 2-methoxyethyl and ethyl.

Further representative examples of R 1 include 1-methylethyl, 1-ethylpropyl, cycloheptyl, cis-4-methylcyclohexyl, trans-4-methylcyclohexyl, cyclobutyl, cyclopentanemethyl, and trans-4-(ethoxy)cyclohexyl.

In another aspect of the invention R 1 is selected from the group consisting of A(CR 6 R 7 ) n and B(CR 6 R 7 ) n .

Further representative examples of R 1 include benzyl, 4-chlorobenzyl, 2-furylmethyl, 4-methylphenyl, 4-fluorophenyl, 4-methoxyphenyl, 3-pyridyl, 2-chlorophenyl, 3,5-difluorobenzyl, 3-pyridylmethyl, 2-methylbenzyl, 2-chlorobenzyl, (S)-α-methylbenzyl, (R)-α-methylbenzyl, 6-methylpyridin-3-yl, 4-methoxybenzyl, 4-fluorobenzyl, 2-(5-methylfuryl)methyl, 4-methylbenzyl, 4-pyridylmethyl, 2-pyridylmethyl, 2-(6-methylpyridine)methyl, 2-thiophenylmethyl, 4-pyranylmethyl, 2-tetrahydrofurylmethyl, 2-(5-methylpyrazine)methyl and 4-ethoxybenzyl.

Further representative examples of R 1 include 1H-imidazol-2-ylmethyl, 1H-pyrazol-4-ylmethyl, (1-methyl-1H-imidazol-2-yl)methyl, (3-methyl-1H-pyrazol-4-yl)methyl, (1-methyl-1H-pyrazol-3-yl)methyl, (1-methyl-1H-pyrazol-4-yl)methyl, (3-methyl-1H-pyrazol-5-yl)methyl, (1-methyl-1H-pyrazol-5-yl)methyl, (1-methyl-1H-1,2,4-triazol-5-yl)methyl, (5-methyl-3-isoxazolyl)methyl, tetrahydro-2H-pyran-4-yl, tetrahydro-2H-pyran-4-ylmethyl, (6-methyl-3-pyridyl)methyl, 2-pyrazinylmethyl, (2-methyl-1H-imidazol-4-yl)methyl, (4-methyl-1H-imidazol-5-yl)methyl, (4-methyl-1H-imidazol-2-yl)methyl, (1-ethyl-1H-imidazol-2-yl)methyl, (1,3-dimethyl-1H-pyrazol-4-yl)methyl, (1,5-dimethyl-1H-pyrazol-4-yl)methyl, (3-methyl-5-isothiazolyl)methyl, (4-methyl-1,3-thiazol-2-yl)methyl, (3-methyl-4-isothiazolyl)methyl, [1-(fluoromethyl)-1H-pyrazol-4-yl]methyl, (2-methyl-3-pyridyl)methyl, (6-methyl-3-pyridyl)methyl, (1-methyl-1H-imidazol-2-yl)methyl, (5-chloro-2-pyridyl)methyl, 1H-imidazol-2-ylmethyl, 4-ethoxyphenyl, 3-chloro-4-methylphenyl, (5-chloro-2-pyridyl)methyl, (6-methyl-3-pyridyl)methyl, 2-methyl-3-pyridyl, 6-methyl-2-pyridyl, 2-pyrazinylmethyl, 2,6-dimethyl-3-pyridyl, 3,4-dichlorobenzyl, 5-chloro-3-pyridyl, 6-chloro-3-pyridazinyl, 3,5-dichlorobenzyl, 2-carboxyphenyl, (5-methyl-2-pyridyl)methyl, 4-chloro-3-(trifluoromethyl)benzyl, (5-bromo-2-pyridyl)methyl, (4-bromo-4-pyridyl)methyl, (3-methyl-4-isoxazolyl)methyl, 5-pyrimidinylmethyl, (3-methyl-1,2,4-oxadiazol-5-yl)methyl, (5-methyl-1,2,4-oxadiazol-3-yl)methyl and (1-ethyl-1H-1,2,4-triazol-5-yl)methyl.

In another aspect of the invention R 1 is selected from the group consisting of C 3-6 alkenyl and C 3-6 alkynyl.

Further representative examples of R 1 include propargyl and allyl.

In another aspect of the invention R 2 is H or C 1-2 alkyl.

Representative examples of R 2 include H, methyl and ethyl.

In another aspect of the invention R 3 is CHF 2 , CH 2 F, CF 3 or C 1-4 alkyl.

Representative examples of R 3 include CF 3 , CH 3 and ethyl.

Further representative examples of R 3 include CH 2 F.

In another aspect of the invention R 4 is C 1-6 alkyl, such as C 1-3 alkyl.

Representative examples of R 4 include CH 3 .

In another aspect of the invention R 4 is NH 2 .

Further representative examples of R 4 include NH 2 .

In another aspect of the invention R 5 is hydrogen or C 1-3 alkyl.

Representative examples of R 5 include H or CH 3 .

In another aspect of the invention R 5 is CN, halogen or CO 2 Et.

Further representative examples of R 5 include CN, F, Cl, CO 2 Et.

In another aspect of the invention R 6 and R 7 are independently selected from H or methyl. In another aspect R 6 and R 7 are both H.

In another aspect of the invention A is selected from the group consisting of

where defines the point of attachment of the ring

and A is unsubstituted or substituted by one or two R 8 .

In another aspect of the invention A is selected from the group consisting of

where defines the point of attachment of the ring

In another aspect of the invention R 8 is selected from the group consisting of halogen, C 1-3 alkyl, C 1-3 alkyl substituted by one to three fluorine atoms (e.g. CF 3 ), and C 1-3 alkoxy.

Representative examples of R 8 include F, Cl, CH 3 , methoxy and ethoxy.

Further representative examples of R 8 include ethyl, fluoromethyl, CF 3 and Br.

Representative examples of B include

In another aspect of the invention R 9 is selected from the group consisting of C 1-6 alkyl (e.g. ethyl), phenyl and aminomethyl.

In another aspect of the invention R 10 is H.

In another aspect of the invention in compounds of formula (I), (IA) and (IB) n is 0 to 2 (e.g. 1) or in compounds of formula (IC) n is 1 or 2.

In another aspect the invention provides a compound of formula (I) or a pharmaceutically acceptable salt thereof in which:

X is oxygen; Y is CH; R 1 is A(CR 6 R 7 ) n ; R 3 is selected from the group consisting of C 1-5 alkyl and C 1-2 alkyl substituted by one to five fluorine atoms; R 4 is C 1-6 alkyl; R 5 is selected from the group consisting of hydrogen, C 1-3 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 1-3 alkylO 2 C, halogen, and C 1-3 alkylS; A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R 8 ; R 8 is selected from the group consisting of halogen, C 1-6 alkyl, C 1-6 alkyl substituted by one more fluorine atoms, C 1-6 alkoxy, and C 1-6 alkoxy substituted by one or more F; R 10 is selected from the group consisting of H and halogen; and n is 0.

Preferred compounds of the invention are:

4-ethyl-6-[4-(methylsulfonyl)phenyl]-N-(tetrahydro-2H-pyran-4-ylmethyl)-2-pyridinamine; 4-methyl-N-[(1-methyl-1H-pyrazol-4-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; N-[(1,5-dimethyl-1H-pyrazol-4-yl)methyl]-4-methyl-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; N-[(1,3-dimethyl-1H-pyrazol-4-yl)methyl]-4-methyl-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; 4-(6-{[(1,3-dimethyl-1H-pyrazol-4-yl)methyl]amino}-4-ethyl-2-pyridinyl)benzenesulfonamide; N-[(1,3-dimethyl-1H-pyrazol-4-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-[(1,5-dimethyl-1H-pyrazol-4-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; 4-{4-methyl-6-[(tetrahydro-2H-pyran-4-ylmethyl)amino]-2-pyridinyl}benzenesulfonamide; 4-methyl-N-[(1-methyl-1H-pyrazol-3-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; N-(cyclohexylmethyl)-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-cyclohexyl-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; 2-[4-(methylsulfonyl)phenyl]-6-[(2-pyridinylmethyl)oxy]-4-(trifluoromethyl)pyridine; 4-methyl-N-[(3-methyl-4-isoxazolyl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; 6-[4-(methylsulfonyl)phenyl]-N-(2-pyridinylmethyl)-4-(trifluoromethyl)-2-pyridinamine; N-cycloheptyl-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-(cis-4-methylcyclohexyl)-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-(1-ethylpropyl)-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-[(3-methyl-1,2,4-oxadiazol-5-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-[(5-methyl-1,2,4-oxadiazol-3-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; 4-methyl-N-[(1-methyl-1H-pyrazol-5-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; N-(cyclopentylmethyl)-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; N-[(1-ethyl-1H-1,2,4-triazol-5-yl)methyl]-4-methyl-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; 4-ethyl-6-[4-(methylsulfonyl)phenyl]-2-[(2-pyridinylmethyl)amino]-3-pyridinecarbonitrile; 4-ethyl-2-{[(5-methyl-2-pyridinyl)methyl]amino}-6-[4-(methylsulfonyl)phenyl]-3-pyridinecarbonitrile; 4-ethyl-2-{[(6-methyl-3-pyridinyl)methyl]amino}-6-[4-(methylsulfonyl)phenyl]-3-pyridinecarbonitrile; 4-ethyl-2-{[(1-methyl-1H-pyrazol-4-yl)methyl]amino}-6-[4-(methylsulfonyl)phenyl]-3-pyridinecarbonitrile; 4-ethyl-6-[4-(methylsulfonyl)phenyl]-2-{[(4-methyl-1,3-thiazol-2-yl)methyl]amino}-3-pyridinecarbonitrile; 4-ethyl-6-[4-(methylsulfonyl)phenyl]-2-[(2-pyridinylmethyl)oxy]-3-pyridinecarbonitrile; 4-ethyl-N-[(1-ethyl-1H-1,2,4-triazol-5-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine; 4-ethyl-2-{[(6-methyl-3-pyridinyl)methyl]oxy}-6-[4-(methylsulfonyl)phenyl]-3-pyridinecarbonitrile; 6-[4-(methylsulfonyl)phenyl]-N-[(1-methyl-1H-1,2,4-triazol-5-yl)methyl]-4-(trifluoromethyl)-2-pyridinamine.

Particularly preferred compounds of the invention are:

N-cyclohexyl-6-[4-(methylsulfonyl)phenyl]-4-(trifluoromethyl)-2-pyridinamine; 2-[4-(methylsulfonyl)phenyl]-6-[(2-pyridinylmethyl)oxy]-4-(trifluoromethyl)pyridine; 4-methyl-N-[(1-methyl-1H-pyrazol-4-yl)methyl]-6-[4-(methylsulfonyl)phenyl]-2-pyridinamine.

It is to be understood that the invention covers all combinations of particular aspects of the invention as described hereinabove.

Since the compounds of the present invention, in particular compounds of formula (I), are intended for use in pharmaceutical compositions, it will be understood that they are each provided in substantially pure form, for example at least 50% pure, more suitably at least 75% pure and preferably at least 95% pure (% are on a wt/wt basis). Impure preparations of the compound of formula (I) may be used for preparing the more pure forms used in pharmaceutical compositions. Although the purity of intermediate compounds of the present invention is less critical, it will be readily understood that the substantially pure form is preferred as for the compounds of formula (I). Preferably, whenever possible, the compounds of the present invention are available in crystalline form.

When some of the compounds of this invention are allowed to crystallise or are recrysallised from organic solvents, solvent of recrystallisation may be present in the crystalline product. This invention includes within its scope such solvates. Similarly, some of the compounds of this invention may be crystallised or recrystallised from solvents containing water. In such cases water of hydration may be formed. This invention includes within its scope stoichiometric hydrates as well as compounds containing variable amounts of water that may be produced by processes such as lyophilisation. In addition, different crystallisation conditions may lead to the formation of different polymorphic forms of crystalline products. This invention includes within its scope all the polymorphic forms of the compounds of formula (I).

Compounds of the invention are potent and selective inhibitors of COX-2. This activity is illustrated by their ability to selectively inhibit COX-2 over COX-1.

In view of their selective COX-2 inhibitory activity, the compounds of the present invention are of interest for use in human and veterinary medicine, particularly in the treatment of the pain (both chronic and acute), fever and inflammation of a variety of conditions and diseases mediated by selective inhibition of COX-2. Such conditions and diseases are well known in the art and include rheumatic fever; symptoms associated with influenza or other viral infections, such as the common cold; lower back and neck pain; headache; toothache; sprains and strains; myositis; sympathetically maintained pain; synovitis; arthritis, including rheumatoid arthritis; degenerative joint diseases, including osteoarthritis; gout and ankylosing spondylitis; tendinitis; bursitis; skin related conditions, such as psoriasis, eczema, burns and dermatitis; injuries, such as sports injuries and those arising from surgical and dental procedures.

The compounds of the invention are also useful for the treatment of neuropathic pain. Neuropathic pain syndromes can develop following neuronal injury and the resulting pain may persist for months or years, even after the original injury has healed. Neuronal injury may occur in the peripheral nerves, dorsal roots, spinal cord or certain regions in the brain. Neuropathic pain syndromes are traditionally classified according to the disease or event that precipitated them. Neuropathic pain syndromes include: diabetic neuropathy; sciatica; non-specific lower back pain; multiple sclerosis pain; fibromyalgia; HIV-related neuropathy; neuralgia, such as post-herpetic neuralgia and trigeminal neuralgia; and pain resulting from physical trauma, amputation, cancer, toxins or chronic inflammatory conditions. These conditions are difficult to treat and although several drugs are known to have limited efficacy, complete pain control is rarely achieved. The symptoms of neuropathic pain are incredibly heterogeneous and are often described as spontaneous shooting and lancinating pain, or ongoing, burning pain. In addition, there is pain associated with normally non-painful sensations such as “pins and needles” (paraesthesias and dysesthesias), increased sensitivity to touch (hyperesthesia), painful sensation following innocuous stimulation (dynamic, static or thermal allodynia), increased sensitivity to noxious stimuli (thermal, cold, mechanical hyperalgesia), continuing pain sensation after removal of the stimulation (hyperpathia) or an absence of or deficit in selective sensory pathways (hypoalgesia).

The compounds of the invention are also useful for the treatment of other conditions mediated by selective inhibition of COX-2.

For example, the compounds of the invention inhibit cellular and neoplastic transformation and metastatic tumour growth and hence are useful in the treatment of certain cancerous diseases, such as colonic cancer and prostate cancer. The compounds of the invention are also useful in reducing the number of adenomatous colorectal polyps and thus reduce the risk of developing colon cancer. The compounds of the invention are also useful in the treatment of cancer associated with overexpression of HER-2/neu, in particular breast cancer.

Compounds of the invention also prevent neuronal injury by inhibiting the generation of neuronal free radicals (and hence oxidative stress) and therefore are of use in the treatment of stroke; epilepsy; and epileptic seizures (including grand mal, petit mal, myoclonic epilepsy and partial seizures).

Compounds of the invention also inhibit prostanoid-induced smooth muscle contraction and hence are of use in the treatment of dysmenorrhoea and premature labour.

Compounds of the invention are also useful in the treatment of liver disease, such as inflammatory liver disease, for example chronic viral hepatitis B, chronic viral hepatitis C, alcoholic liver injury, primary biliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitis and liver transplant rejection.

Compounds of the invention inhibit inflammatory processes and therefore are of use in the treatment of asthma, allergic rhinitis and respiratory distress syndrome; gastrointestinal conditions such as inflammatory bowel disease, Crohn's disease, gastritis, irritable bowel syndrome and ulcerative colitis; and the inflammation in such diseases as vascular disease, migraine, periarteritis nodosa, thyroiditis, aplastic anaemia, Hodgkin's disease, sclerodoma, type I diabetes, myasthenia gravis, multiple sclerosis, sorcoidosis, nephrotic syndrome, Bechet's syndrome, polymyositis, gingivitis, conjunctivitis and myocardial ischemia.

Compounds of the invention are also useful in the treatment of ophthalmic diseases such as retinitis, retinopathies, uveitis and of acute injury to the eye tissue.

Compounds of the invention are also useful for the treatment of cognitive disorders such as dementia, particularly degenerative dementia (including senile dementia, Alzheimer's disease, Pick's disease, Huntington's chorea, Parkinson's disease and Creutzfeldt-Jakob disease), and vascular dementia (including multi-infarct dementia), as well as dementia associated with intracranial space occupying lesions, trauma, infections and related conditions (including HIV infection), metabolism, toxins, anoxia and vitamin deficiency; and mild cognitive impairment associated with ageing, particularly Age Associated Memory Impairment.

Compounds of the invention are also useful in the treatment of disorders ameliorated by a gastroprokinetic agent. Disorders ameliorated by gastroprokinetic agents include ileus, for example post-operative ileus and ileus during sepsis; gastroesophageal reflux disease (GORD, or its synonym GERD); gastroparesis, such as diabetic gastroparesis; and other functional bowel disorders, such as non-ulcerative dyspepsia (NUD) and non-cardiac chest pain (NCCP).

According to a further aspect of the invention, we provide a compound of formula (I) for use in human or veterinary medicine.

According to a further aspect of the invention, we provide a method of treating a human or animal subject suffering from a condition which is mediated by COX-2 which comprises administering to said subject an effective amount of a compound of formula (I).

According to a further aspect of the invention, we provide a method of treating a human or animal subject suffering from an inflammatory disorder, which method comprises administering to said subject an effective amount of a compound of formula (I).

According to another aspect of the invention, we provide the use of a compound of formula (I) for the manufacture of a therapeutic agent for the treatment of a condition which is mediated by COX-2.

According to another aspect of the invention, we provide the use of a compound of formula (I) for the manufacture of a therapeutic agent for the treatment of an inflammatory disorder.

It is to be understood that reference to treatment includes both treatment of established symptoms and prophylactic treatment, unless explicitly stated otherwise.

It will be appreciated that the compounds of the invention may advantageously be used in conjunction with one or more other therapeutic agents. Examples of suitable agents for adjunctive therapy include a 5HT 1 agonist, such as a triptan (e.g. sumatriptan or naratriptan); an adenosine A1 agonist; an EP ligand; an NMDA modulator, such as a glycine antagonist; a sodium channel blocker (e.g. lamotrigine); a substance P antagonist (e.g. an NK 1 antagonist); a cannabinoid; acetaminophen or phenacetin; a 5-lipoxygenase inhibitor; a leukotriene receptor antagonist; a DMARD (e.g. methotrexate); gabapentin and related compounds; a tricyclic antidepressant (e.g. amitryptilline); a neurone stabilising antiepileptic drug; a mono-aminergic uptake inhibitor (e.g. venlafaxine); a matrix metalloproteinase inhibitor; a nitric oxide synthase (NOS) inhibitor, such as an iNOS or an nNOS inhibitor; an inhibitor of the release, or action, of tumour necrosis factor α; an antibody therapy, such as a monoclonal antibody therapy; an antiviral agent, such as a nucleoside inhibitor (e.g. lamivudine) or an immune system modulator (e.g. interferon); an opioid analgesic; a local anaesthetic; a stimulant, including caffeine; an H 2 -antagonist (e.g. ranitidine); a proton pump inhibitor (e.g. omeprazole); an antacid (e.g. aluminium or magnesium hydroxide; an antiflatulent (e.g. simethicone); a decongestant (e.g. phenylephrine, phenylpropanolamine, pseudoephedrine, oxymetazoline, epinephrine, naphazoline, xylometazoline, propylhexedrine, or levo-desoxyephedrine); an antitussive (e.g. codeine, hydrocodone, carmiphen, carbetapentane, or dextramethorphan); a diuretic; or a sedating or non-sedating antihistamine. It is to be understood that the present invention covers the use of a compound of formula (I) in combination with one or more other therapeutic agents.

The compounds of formula (I) are conveniently administered in the form of pharmaceutical compositions. Thus, in another aspect of the invention, we provide a pharmaceutical composition comprising a compound of formula (I) adapted for use in human or veterinary medicine. Such compositions may conveniently be presented for use in conventional manner in admixture with one or more physiologically acceptable carriers or excipients.

As will be appreciated by the person skilled in the art the compounds of the invention may be milled using known milling procedures such as wet milling to obtain a particle size appropriate for tablet formation and for other formulation types. In particular, for those compounds which demonstrate poor bioavailability, finely divided (nanoparticulate) preparations of the compounds of the invention may be prepared by processes known in the art, for example see International Patent Application No. WO 02/00196 (SmithKline Beecham).

The compounds of formula (I) may be formulated for administration in any suitable manner. They may, for example, be formulated for topical administration or administration by inhalation or, more preferably, for oral, transdermal or parenteral administration. The pharmaceutical composition may be in a form such that it can effect controlled release of the compounds of formula (I).

For oral administration, the pharmaceutical composition may take the form of, for example, tablets (including sub-lingual tablets), capsules, powders, solutions, syrups or suspensions prepared by conventional means with acceptable excipients.

For transdermal administration, the pharmaceutical composition may be given in the form of a transdermal patch, such as a transdermal iontophoretic patch.

For parenteral administration, the pharmaceutical composition may be given as an injection or a continuous infusion (e.g. intravenously, intravascularly or subcutaneously). The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. For administration by injection these may take the form of a unit dose presentation or as a multidose presentation preferably with an added preservative.

Alternatively for parenteral administration the active ingredient may be in powder form for reconstitution with a suitable vehicle.

The compounds of the invention may also be formulated as a depot preparation. Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds of the invention may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

As stated above, the compounds of the invention may also be used in combination with other therapeutic agents. The invention thus provides, in a further aspect, a combination comprising a compound of formula (I) together with a further therapeutic agent.

The combinations referred to above may conveniently be presented for use in the form of a pharmaceutical formulation and thus pharmaceutical formulations comprising a combination as defined above together with a pharmaceutically acceptable carrier or excipient comprise a further aspect of the invention. The individual components of such combinations may be administered either sequentially or simultaneously in separate or combined pharmaceutical formulations.

When a compound of formula (I) is used in combination with a second therapeutic agent active against the same disease state the dose of each compound may differ from that when the compound is used alone. Appropriate doses will be readily appreciated by those skilled in the art.

A proposed daily dosage of a compound of formula (I) for the treatment of man is 0.01 mg/kg to 500 mg/kg, such as 0.05 mg/kg to 100 mg/kg, e.g. 0.1 mg/kg to 50 mg/kg, which may be conveniently administered in 1 to 4 doses. The precise dose employed will depend on the age and condition of the patient and on the route of administration. Thus, for example, a daily dose of 0.25 mg/kg to 10 mg/kg may be suitable for systemic administration.

Compounds of formula (I) may be prepared by any method known in the art for the preparation of compounds of analogous structure.

Compounds of formula (I) may be prepared by a process which comprises:

reacting a compound R 1 XH of formula (II), or a protected derivative thereof, with a compound of formula (III)

where X is as defined and Z is halogen, such as F, Cl, Br or I, or a sulfonate, such as (4-methyl)benzenesulfonate or trifluoromethanesulfonate and thereafter and if necessary,

interconverting a compound of formula (I) into another compound of formula (I); and/or deprotecting a protected derivative of compound of formula (I).

The overall synthesis of a compound of formula (I) is shown in Scheme 1 below in which, R 1 to R 3 , R 5 , X and Y are as defined in formula (I) unless otherwise stated, R 4 is C 1-6 alkyl and Z is a halogen, such as F, Cl, Br or I, or a sulfonate, such as (4-methyl)benzenesulfonate or trifluoromethanesulfonate; LDA is lithium diisopropylamide; THF is tetrahydrofuran.

Referring to Scheme 1, pyridines of formula (I) where R 5 =Cl can be obtained by treatment of pyridines of formula (I) where R 5 =H with a chlorinating agent, such as N-chlorosuccinimide, in a solvent, such as acetic acid and at ambient temperature.

Referring to Scheme 1, when X=NR 2 , compounds of formula (I) may be prepared via the treatment of compounds of formula (III) with an amine of formula (II). This is conveniently carried out in a solvent, such as a nitrile (e.g. methylnitrile) and at elevated temperature (e.g. from about 50° C. to reflux). An excess of the amine may be used in place of the solvent.

Alternatively, the treatment of compounds of formula (III) with an amine of formula (II) is conveniently carried out in a solvent, such as a tertiary amine (e.g. NMP, N-methylpyrrolidinone) and at elevated temperature (e.g. from 120° C. to 250° C.) and with or without microwave irradiation.

Alternatively, the treatment of compounds of formula (III) with an amine of formula (II) may be carried out in the presence of a catalytic quantity of a palladium salt, such as palladium (II) acetate, a phosphine ligand, such as 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP), and a base, such as cesium carbonate or sodium tert-butoxide. The reaction is conveniently carried out in a solvent such as toluene or 1,4-dioxan and at elevated temperature.

Alternatively, the treatment of compounds of formula (III) with an amine of formula (II) may be carried out in the presence of a base, such as sodium hydride. The reaction is conveniently carried out in a solvent, such as THF, DMF (N,N-dimethylformamide) or NMP (N-methylpyrrolidinone), at between ambient and elevated temperature (e.g. elevated temperature) and with or without microwave irradiation.

Referring to Scheme 1, when X=O, compounds of formula (I) may be prepared by the treatment of compounds of formula (III) with an alcohol of formula (II) in the presence of a base such as sodium hydride. The reaction is conveniently carried out in a solvent such as THF and at between ambient temperature and reflux.

Alternatively, when X=O, compounds of formula (I) may be prepared by treatment of 2-pyridones of formula (IV) with an alkyl halide in the presence of a base, such as silver carbonate, and in a solvent, such as DMF (N,N-dimethylformamide) or n-pentane.

Alternatively, when X=O, 2-pyridones of formula (IV) may be converted to compounds of formula (I) by a Mitsunobu reaction, employing an alcohol of formula (II), a dialkylazodicarboxylate, such as diisopropylazodicarboxylate, a trialkyl- or triarylphosphine, such as tributylphosphine or triphenylphosphine. The reaction is conveniently carried out in a solvent, such as chloroform or THF.

Referring to Scheme 1,2-pyridones of formula (IV) where R 5 =H can be converted to 2-pyridones of formula (IV) where R 5 =F by treatment with a fluorinating agent, such as SELECTFLUOR™ [1-(chloromethyl)-4-fluoro-1,4,-diazoniabicyclo[2.2.2]octane bis-tetrafluoroborate], in a solvent such as acetonitrile, and at between ambient and elevated temperature (eg elevated temperature)

Referring to Scheme 1,2-pyridones of formula (IV) where R 5 =H can be converted to 2-pyridones of formula (IV) where R 5 =Cl or Br by treatment with a halogenating agent, such as N-chlorosuccinimide or N-bromosuccinimide, in a solvent, such as acetic acid and at ambient temperature.

Referring to Scheme 1, the conversion of 2-pyridones of formula (IV) to the corresponding pyridines of formula (III) where Z is chlorine or bromine, is conveniently carried out employing a phosphorous halide species (e.g. phosphorous (V) chloride) in a solvent, such as a phosphorous oxyhalide (e.g. phosphorous oxychloride), and at between ambient and elevated temperature (e.g. elevated temperature). Compounds of formula (III) where Z is chlorine or bromine may be converted to compounds of formula (III) where Z is fluorine or iodine using standard interconversion techniques such as those described in ‘Comprehensive Organic Transformations: a guide to functional group preparations’ by Richard Larock (VCH, 1989), incorporated herein by reference.

Alternatively, the conversion of 2-pyridones of formula (IV) to the corresponding pyridines of formula (III) where Z is a sulfonate, is conveniently carried out in a solvent, such as a nitrogen-containing solvent (e.g. pyridine) and employing a reagent such as a sulfonyl halide (e.g. (4-methyl)benzenesulfonyl chloride) or a sulfonic anhydride (e.g. trifluoromethanesulfonic anhydride).

Conveniently the oxidation shown in Scheme 1 is carried out using a monopersulfate compound, such as potassium peroxymonopersulfate (known as Oxone™) and the reaction is carried out in a solvent, such as an aqueous alcohol (e.g. aqueous methanol) and at between −78° C. and ambient temperature.

Alternatively, the oxidation shown in Scheme 1 may be effected using hydrogen peroxide in the presence of sodium tungstate dihydrate. The reaction may be carried out in a solvent such as acetic acid and at between ambient temperature and reflux (e.g. 50° C.).

Referring to Scheme 1, pyridones of formula (V) are conveniently prepared by treating α,β-unsaturated acids of formula (VII) with two equivalents of LDA in THF at −78° C., followed by a nitrile of formula (VI), according to the procedure described by E. M. Brown, S. Gil, R. Mestres and M. Pavra in Synthesis, 2000, 2, pp 273-280, incorporated herein by reference.

Alternatively, pyridones of formulae (IV) and (V) may be prepared as shown in Scheme 2 below.

Referring to Scheme 2, compounds of formula (V) (R 5 =H) may be prepared by treatment of compounds of formula (XIV) with ammonia. The reaction is conveniently carried out in a mixture of concentrated aqueous ammonia and dioxane at elevated temperature and in a sealed vessel.

Referring to Scheme 2, compounds of formula (XIV) may be obtained by treatment of compounds of formula (XVII) with a dialkyl malonate (e.g. diethyl malonate) in the presence of a base, such as sodium hydride or a metal alkoxide (e.g. sodium ethoxide). The reaction is conveniently carried out in a solvent, such as THF or an alcohol (e.g. ethanol).

Referring to Scheme 2, compounds of formula (IV) (R 5 ≠H) may be prepared by treatment of compounds of formula (XV) with a compound of formula (XVI) in the presence of a base, such as sodium hydride or a metal alkoxide (e.g. sodium ethoxide). The reaction is conveniently carried out in a solvent, such as THF or an alcohol (e.g. ethanol).

Referring to Scheme 2 compounds of formula (XIX) may be converted to compounds of formula (XVII) by treatment with an alkynylmetal species, such as an alkynyllithium species or an alkynyl Grignard reagent. The reaction is conveniently carried out in a solvent, such as THF, and at between −78° C. and ambient temperature.

Referring to Scheme 2, compounds of formula (XIX) may be obtained by treatment of compounds of formula (XX) with morpholine in the presence of an amide coupling reagent, such as dicyclohexylcarbodiimide (DCC) or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) in a solvent such as THF. The reaction may also be carried out in the presence of a base, such as triethylamine or (N,N-diisopropyl)ethylamine.

The synthesis of an intermediate of formula (III) in which R 3 , R 5 and Y are as defined for compounds of formula (I), Z is a halogen, such as F, Cl, Br or I, or a sulfonate such as (4-methyl)benzenesulfonate or trifluoromethanesulfonate, and R 4 is NH 2 , is shown in Scheme 3 below. P represents a suitable protecting group.

Referring to Scheme 3, compounds of formula (IX) may be prepared from compounds of formula (VII) in an analogous manner to that described in Scheme 1. Protection of the sulfonamide functionality of the benzonitrile (VIII) may be achieved using a silicon protecting group, such as the 2-(trimethylsilyl)-ethoxymethyl (SEM) group which can be introduced under standard conditions.

Referring to Scheme 3, the conversion of 2-pyridones of formula (IX) to the corresponding pyridines of formula (III) where Z is halogen, is conveniently carried out employing a phosphorous halide species (e.g. phosphorous (V) chloride) in a solvent, such as a phosphorous oxyhalide (e.g. phosphorous oxychloride), and at between ambient and elevated temperature (e.g. elevated temperature).

Alternatively, the conversion of 2-pyridones of formula (IX) to the corresponding pyridines of formula (III) where Z is a sulfonate, is conveniently carried out in a solvent, such as a nitrogen-containing solvent (e.g. pyridine) and employing a reagent such as a sulfonyl halide (e.g. (4-methyl)benzenesulfonyl chloride) or a sulfonic anhydride (e.g. trifluoromethanesulfonic anhydride).

In all alternatives described hereinabove in relation to Scheme 3 for the conversion of (IX) to (III), removal of the protecting groups can be achieved using a source of fluoride, such as tetrabutylammonium fluoride (TBAF), in a suitable organic solvent such as THF, at a temperature between ambient and reflux.

Conversion of the intermediates of formula (III) to compounds of formula (I) can be achieved as described for Scheme 1. In one variation the nitrogen protecting groups on the sulfonamide functionality may be retained during the transformation of intermediates of formula (III) to compounds of formula (I). In some circumstances removal of the protecting groups occurs during the treatment of intermediate (III) with R 1 XH (II). Alternatively, the protecting groups may be removed after treatment of (III) with (II) using the standard deprotection conditions described above.

In one variation of Scheme 1, compounds of formula (III) in which Z is halogen, such as F, Cl, Br and I and Y═C, may be synthesised according to Scheme 4 below. R 1 to R 3 , R 5 and Y are as defined in formula (I) unless otherwise stated, R 4 is C 1-6 alkyl, M represents B(OH) 2 or B(OR) 2 and m is 0, 1 or 2.

Referring to Scheme 4, compounds of formula (XIII) may be converted to compounds of formula (XI) via a Suzuki coupling reaction employing a palladium source, such as palladium tetrakistriphenylphosphine Pd(PPh 3 ) 4 , or Pd 2 (dba) 3 and a ligand, such as triphenylphosphine or tri(tertbutyl)phosphine, and a base, such as sodium carbonate, potassium phosphate or potassium fluoride, in a solvent such as a water/toluene mix, a water/dimethoxyethane mix or 1,4-dioxan.

Conveniently, the oxidation shown in Scheme 4 is carried out using 3-chloroperoxybenzoic acid (m-CPBA) in a chlorinated solvent, such as dichloromethane or chloroform, or a mixture of a chlorinated solvent and aqueous sodium bicarbonate (NaHCO 3 ). The oxidation is performed at between 0° C. and ambient temperature.

Alternatively, the oxidation shown in Scheme 4 may be conveniently carried out in a two-step process, treating compounds of formula (XI) (m=0) firstly with oxone, and secondly with mCPBA in a chlorinated solvent, such as dichloromethane or chloroform, or a mixture of a chlorinated solvent and aqueous sodium bicarbonate (NaHCO 3 ). The oxidation is performed at between 0° C. and ambient temperature.

The transformation of (X) to the intermediate (III) may conveniently be achieved via treatment of (X) with a phosphorous halide species (e.g. phosphorous (V) chloride) in a solvent, such as a phosphorous oxyhalide (e.g. phosphorous oxychloride), and at between ambient and elevated temperature (e.g. elevated temperature).

Pyridines of formula (XIII) are either known compounds or, when R 3 is C 1-2 alkyl substituted by one to five fluorine atoms, may be prepared from 2-chloroisonicotinic acid by standard transformations. For example, when R 3 is CH 2 F or CHF 2 , this can be conveniently achieved by reduction of 2-chloroisonicotinic acid using borane followed by fluorination of the resulting alcohol using a suitable reagent such as DAST, or oxidation of the alcohol, followed by fluorination of the resulting aldehyde with a suitable reagent such as DAST.

It will be appreciated by those skilled in the art that certain of the procedures described in Schemes 1 to 4 for the preparation of compounds of the formula (I) or intermediates thereto may not be applicable to some of the possible substituents.

It will be further appreciated by those skilled in the art that it may be necessary to carry out the transformations described in Schemes 1 to 4 in a different order from that described, or to modify one or more of the transformations, to provide the desired compound of formula (I).

It will be appreciated by those skilled in the art that compounds of formula (I) may be prepared by interconversion, utilising other compounds of formula (I) as precursors. Suitable interconversions, such as alkylations, are well known to those skilled in the art and are described in many standard organic chemistry texts, such as ‘Advanced Organic Chemistry’ by Jerry March, fourth edition (Wiley, 1992), incorporated herein by reference. For example, compounds of formula (I) wherein R 1 is C 1-6 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 3-6 alkenyl, C 3-6 alkynyl, C 3-10 cycloalkylC 0-6 alkyl, C 4-12 bridged cycloalkyl, A(CR 6 R 7 ) n (with the proviso that n is not zero) or B(CR 6 R 7 ) n may be prepared by alkylating the corresponding compound of formula (I) wherein R 1 is H.

Acylation of compounds of formula (I) wherein R 4 is NH 2 , to provide compounds of formula (I) wherein R 4 is R 9 CONH, may be carried out by conventional means, for example by employing conventional acylating agents such as those described in ‘Advanced Organic Chemistry’, pp 417-424, incorporated herein by reference.

As will be appreciated by those skilled in the art it may be necessary or desirable at any stage in the synthesis of compounds of formula (I) to protect one or more sensitive groups in the molecule so as to prevent undesirable side reactions. The protecting groups used in the preparation of compounds of formula (I) may be used in conventional manner. See, for example, those described in ‘Protective Groups in Organic Synthesis’ by Theodora W. Greene and Peter G. M. Wuts, third edition, (Wiley, 1999), incorporated herein by reference, which also describes methods for the removal of such groups.

Amines and alcohols of formula (II) are either known compounds or may be prepared by literature methods, such as those described in ‘Comprehensive Organic Transformations: a guide to functional group preparations’ by Richard Larock (VCH, 1989), incorporated herein by reference.

Benzonitriles of formula (VI) are either known compounds or may be prepared by literature methods, such as that described by G. Atwell et al in Anti - Cancer Drug Design 1996, 11, 553, incorporated herein by reference. Where Y═N, nitriles of formula (VI) may be obtained by treating 5-bromo-2-pyridinecarbonitrile with a suitable nucleophile, such as sodium methanethiolate.

α,β-Unsaturated acids of formula (VII) are either known compounds or may be prepared by literature methods, such as that described by C. Kuroda et al in Tetrahedron 2000, 56, 6441, incorporated herein by reference.

Certain intermediates described above are novel compounds, and it is to be understood that all novel intermediates herein form further aspects of the present invention. Compounds of formulae (III) and (IV) are key intermediates and represent a particular aspect of the present invention.

Conveniently, compounds of the invention are isolated following work-up in the form of the free base. Pharmaceutically acceptable addition salts of the compounds of the invention may be prepared using conventional means.

Solvates (e.g. hydrates) of a compound of the invention may be formed during the work-up procedure of one of the aforementioned process steps.

The Intermediates and Examples that follow illustrate the invention but do not limit the invention in any way. All temperatures are in ° C. Silica chromatography refers to either flash column chromatography performed using Biotage column chromatography cartridges or Solid Phase Extraction (SPE) chromatography, using Varian Mega Bond Elut (Si) cartridges (Anachem) under 15 mmHg. Thin layer chromatography (Tlc) was carried out on silica plates. Nuclear magnetic resonance (NMR) spectra were recorded using a Bruker DPX400 spectrometer. Analytical HPLC was conducted on a Supelcosil LCABZ+PLUS column (3.3 cm×4.6 mm ID) eluting with 0.1% HCO 2 H and 0.01 M ammonium acetate in water (solvent A), and 0.05% HCO 2 H 5% water in acetonitrile (solvent B), using the following elution gradient 0-0.7 minutes 0% B, 0.7-4.2 minutes linear gradient to 100% B, 4.2-5.3 minutes 0% B, 5.3-5.5 minutes 0% B at a flow rate of 3 ml/minutes. The mass spectra (MS) were recorded on a Waters ZQ mass spectrometer using electrospray positive [(ES+ve to give MH+ and M(NH4)+ molecular ions] or electrospray negative [(ES−ve to give (M−H)— molecular ion] modes. Mass-directed preparative HPLC was conducted on a Supelco ABZ+ column (10 cm×10 mm ID, 5 μm) eluting with 0.1% HCO 2 H in water (solvent A), and 0.05% HCO 2 H/5% water in acetonitrile (solvent B), using the following 10-minute elution gradients according to the LC retention time: 1.5-2.2 mins, 0-30% B; 2.0-2.8 mins, 5-30% B; 2.5-3.0 mins, 15-55% B; 2.8-4.0 mins, 30-80% B; 3.8-5.5 mins, 50-90% B. The mass spectra (MS) were recorded on a Micromass ZMD mass spectrometer using electrospray positive [(ES+ve to give MH+ and M(NH4)+ molecular ions] or electrospray negative [(ES−ve to give (M−H)— molecular ion] modes. In addition to those already defined, the following abbreviations are used: Me, methyl; NMP, N-methylpyrrolidinone; and THF, tetrahydrofuran.

Intermediate 1

4-Methyl-6-[4-(methylthio)phenyl]-2-pyridone

To a stirred solution of lithium diisopropylamide (50 mL of a 2M solution in heptane/THF/ethyl benzene, 0.1 mol) in THF (50 mL) at −78° C. and under an atmosphere of nitrogen was added dropwise a solution of 3-methyl-2-butenoic acid (5 g, 0.05 mol) in THF (50 mL). The reaction was warmed to 0° C. for 30 minutes. After cooling to −78° C., a solution of 4-(methylthio)benzonitrile (7.45 g, 0.05 mol) in THF (50 mL) was added dropwise. Upon complete addition, the reaction was warmed to room temperature and stirred for 3 hours. Water (150 mL) and ethyl acetate (100 mL) were added to the reaction mixture and the resulting precipitate filtered, washed with ethyl acetate and dried to give the title compound (4.96 g, 43%) LC retention time 2.75 mins, MS m/z 232 (MH + ).

Intermediate 2

4-Methyl-6-[4-(methylsulfonyl)phenyl]-2-pyridone

To a stirred mixture of intermediate 1 (3.7 g, 16.0 mmol) in methanol (150 mL) at 0° C. was added portionwise a suspension of Oxone™ (29.5 g, 48.0 mmol) in water (100 mL). The reaction was warmed to room temperature and stirred for 14 hours. The methanol was removed in vacuo and the resulting residue partitioned between saturated aqueous sodium bicarbonate (1 L) and chloroform (500 mL) and separated. The aqueous layer was further extracted with chloroform (3×200 mL) and the combined organic layers were dried over sodium sulfate, filtered and concentrated to give the title compound (3.20 g, 76%) LC retention time 2.20 mins, MS m/z 264 (MH + ).

Intermediate 3

4-Methyl-6-[4-(methylsulfonyl)phenyl]pyridine-2-trifluoromethanesulfonate

To a stirred solution of intermediate 2 (3.20 g, 12.2 mmol) in pyridine (150 mL) at 0° C. and under an atmosphere of nitrogen was added dropwise trifluoromethanesulfonic anhydride (2.46 mL, 14.6 mmol). After stirring for 1 hr at 0° C., the pyridine was removed in vacuo and the residue partitioned between water (200 mL) and dichloromethane (200 mL). The layers were separated and the aqueous phase further extracted with dichloromethane (3×100 mL). The combined organic layers were dried over sodium sulfate, filtered and concentrated in vacuo to give the title compound (4.27 g, 89%) LC retention time 3.48 mins, MS m/z 396 (MH + ).