Patent ID: 7968580

Claim:
A compound of formula (I) R 1 is hydrogen; R 2 is lower alkyl or halogen substituted lower alkyl and R 3 is carboxy, —C(O)-(lower alkyl), or —C(O)—N(R B ) 2 ; wherein each R B is independently selected from hydrogen, lower alkyl and aryl provided that if present, only one R B is aryl; wherein the aryl is optionally substituted with one or more substituents independently selected from halogen, hydroxy, carboxy, lower alkyl, halogen substituted lower alkyl, lower alkoxy, halogen substituted lower alkoxy, cyano, nitro, amino, lower alkylamino or di(lower alkyl)amino; R 4 is selected from the group consisting halogen, hydroxy, carboxy, lower alkyl, halogen substituted lower alkyl, lower alkoxy, halogen substituted lower alkoxy, cyano, nitro, amino, lower alkylamino, di(lower alkyl)amino, —C(O)-(lower alkyl), —C(O)-(lower alkoxy), —C(O)—N(R A ) 2 , —S(O) 0-2 -(lower alkyl), —SO 2 —N(R A ) 2 , —N(R A )—C(O)-(lower alkyl), —N(R A )—C(O)-(halogen substituted lower alkyl) and aryl; wherein each R A is independently selected from hydrogen or lower alkyl; wherein the aryl is optionally substituted with one or more substituents independently selected from halogen, hydroxy, carboxy, lower alkyl, halogen substituted lower alkyl, lower alkoxy, halogen substituted lower alkoxy, cyano, nitro, amino, lower alkylamino or di(lower alkyl)amino; a is an integer from 0 to 4; b is an integer from 0 to 1; or a pharmaceutically acceptable salt thereof.