Patent ID: 7425639

Claim:
A process for preparation of a compound of Formula (IA) or a pharmaceutically acceptable salt thereof: wherein: R 1 represents an aryl or phenoxymethyl group, each of which is optionally substituted by one or more substituents selected from: halogen, C 1-6 alkoxy, C 1-6 alkyl, nitro, cyano, trifluoromethyl, —NR 8 R 9 and —NHSO 2 R 8 ; R 2 represents hydrogen or C 1-6 alkyl; R 3 represents hydrogen or C 1-6 alkyl; X 1 and X 2 independently represent (a) hydrogen, (b) C 1-6 alkylCO, or (c) an aryl CO group optionally substituted by halogen or a C 1-6 alkyl group, with the proviso that when one is (b) or (c) the other is hydrogen (a); R 4 represents a group (W): wherein A represents an aryl, pyridine, thiophene or furan group; R 5 represents cyano, tetrazol-5-yl, —CO 2 H or —CO 2 R 8 ; R 6 and R 7 independently represent hydrogen, C 1-6 alkyl, —CO 2 H, —CO 2 R 8 , cyano, tetrazol-5-yl, halogen, trifluoromethyl or C 1-6 alkoxy, or when R 6 and R 7 are bonded to adjacent carbon atoms, R 6 and R 7 may, together with the carbon atoms to which they are bonded, form a fused 5- or 6- membered ring optionally having one or two nitrogen, oxygen or sulfur atoms; each R 12 independently represents substituents selected from: C 1-6 alkyl, halogen, trifluoromethyl and C 1-6 alkoxy, and n represents an integer from 0-4; and R 8 and R 9 independently represent C 1-6 alkyl; comprising hydrolysis of a compound of Formula (IB) or a pharmaceutically acceptable salt thereof: wherein: R 1 represents an aryl or phenoxymethyl group, each of which is optionally substituted by one or more substituents selected from: halogen, C 1-6 alkoxy, C 1-6 alkyl, nitro, cyano, trifluoromethyl, —NR 8 R 9 and —NHSO 2 R 8 ; R 2 represents hydrogen or C 1-6 alkyl; R 3 represents hydrogen or C 1-6 alkyl; R 4 represents a group (W): wherein A represents an aryl, pyridine, thiophene or furan group; R 5 represents cyano, tetrazol-5-yl or —CO 2 R 8 ; R 6 and R 7 independently represent hydrogen, C 1-6 alkyl, —CO 2 R 8 , cyano, tetrazol-5-yl, halogen, trifluoromethyl, or C 1-6 alkoxy, or when R 6 and R 7 are bonded to adjacent carbon atoms, R 6 and R 7 may, together with the carbon atoms to which they are bonded, form a fused 5- or 6- membered ring optionally having one or two nitrogen, oxygen or sulfur atoms; each R 12 independently represents substituents selected from: C 1-6 alkyl, halogen, trifluoromethyl and C 1-6 alkoxy, and n represents an integer from 0-4; R 8 and R 9 independently represent C 1-6 alkyl; and R 11 represents C 1-6 alkyl or aryl optionally substituted by C 1-6 alkyl or halogen.