Patent ID: 8263656

Claim:
A compound of formula I: or a pharmaceutically acceptable salt or ester thereof, wherein: R 1 is hydrogen, halogen, methoxy, or phenyl; and R 2 is hydrogen, fluoro, chloro, or alkyl; with the proviso that R 1 and R 2 are not both hydrogen; R 3 is hydrogen or methyl; and R 4 is phenyl substituted by two substituents independently selected from the group consisting of: (1) halogen, (2) lower alkyl optionally substituted by halogen, (3) lower alkanoyl, (4) lower alkoxy, (5) lower alkylsulfanyl, lower alkylsulfinyl, or lower alkylsulfonyl, and (6) lower cycloalkylsulfanyl, lower cycloalkylsulfinyl, or lower cycloalkylsulfonyl; or alternatively, R 4 is pyridine substituted by one or two substituents independently selected from the group consisting of: (1) halogen, (2) lower alkyl optionally substituted by halogen, and (3) phenyl or pyridine, wherein said phenyl or pyridine is optionally substituted by lower alkyl, lower alkylsulfanyl, lower alkylsulfonyl, lower cycloalkylsulfanyl, or lower cycloalkylsulfonyl.