Patent ID: 8124633

Claim:
A compound of the formula I: or a pharmaceutically acceptable salt thereof and individual enantiomers and diastereomers thereof wherein: R 1 is X is independently selected from the group consisting of: (1) hydrogen, and (2) fluorine; Y is independently selected from the group consisting of: (1) hydrogen, and (2) methyl; and Z is independently selected from the group consisting of: (1) hydrogen, (2) C 1-6 alkyl, which is unsubstituted or substituted with halogen, hydroxyl or phenyl, (3) —(CO)—C 1-6 alkyl, (4) —(CO)-Aryl (5) —(CO)O—C 1-6 alkyl, (6) —(CO)—NH 2 , (7) —(CO)—NHC 1-6 alkyl, and (8) —(CO)—N(C 1-6 alkyl)(C 1-6 alkyl).