Patent ID: 8329730

Claim:
A compound of formula (I) or a salt thereof: wherein one of R 3 and R 4 is hydrogen and the other is (a) A is a phenyl or a 5 or 6-membered heteroaryl ring; R 1 is hydrogen or up to two substituents independently selected from halogen, C (1-4) alkyl, C (1-4) alkoxy, trifluoromethoxy, difluoromethoxy, (2,2,2-trifluoroethyl)oxy, cyclopropyloxy, (cyclopropylmethyl)oxy, 3-oxetanyloxy, trifluoromethyl, cyano, C (1-4) alkenoxy and pyrollidinyl substituted by halogen; R 2 is hydrogen, —(C 1-5 alkyl)COOH, or —NH(C 1-5 alkyl)COOH, —(C 1-5 alkyl)OH, —(C 1-4 alkyl)CONR 5 R 6 , —(C 1-2 alkyl)NR 5 R 6 , —(C 1-4 alkyl)NR 8 COR 9 , —(C 1-4 alkyl)NR 10 SO 2 R 11 , —(CH 2 ) 2 SO 2 Me, —NR 5 R 6 or any one of groups (i) to (xii): R 5-8 , R 10 and R 12 are each independently selected from hydrogen and C 1-3 alkyl; R 9 and R 11 are each independently selected from C 1-3 alkyl; and n is 1 or 2.