Patent ID: 7691863

Claim:
A compound of the formula: or a pharmaceutically acceptable salt thereof, wherein: (a) R 2 is hydrogen and R 1 is selected from the group consisting of: (1) lower alkyl, (2) lower hydroxyalkyl, (3) cycloalkyl, which is optionally substituted by a substituent selected from the group consisting of hydroxy, lower alkoxy and lower hydroxyalkyl, (4) lower cycloalkylalkyl, (5) lower heterocyclylalkyl, (6) —CR 5 R 6 —COOR 7 , and (7) —CR 5 R 6 —CONH 2 ; (b) one of R 3 and R 4 is —OR 8 and the other one of R 3 and R 4 is selected from the group consisting of: (1) lower alkylamino, (2) lower dialkylamino, (3) cycloalkylamino, and (4) a heterocyclic ring selected from the group consisting of azetidinyl, pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl and azepanyl, wherein said heterocyclic ring is optionally substituted by halogen; (c) R 5 is hydrogen or lower alkyl; (d) R 6 is hydrogen or lower alkyl, (e) R 7 is lower alkyl; (f) R 8 is selected from the group consisting of: (1) lower alkyl, (2) lower halogenalkyl, (3) lower cycloalkylalkyl, (4) lower phenylalkyl, wherein the phenyl is optionally substituted by a substituent selected from the group consisting of lower alkyl, lower alkoxy and halogen, (5) lower heteroarylalkyl, (6) lower alkoxyalkyl, and (7) lower hydroxyalkyl.