Patent ID: 8450497

Claim:
A compound of formula (I) wherein: a is an integer from 0 to 2; each R 0 is independently selected from the group consisting of halogen, C 1-2 alkyl, and fluorinated C 1-2 alkyl; R 2 is hydrogen; R 1 is selected from the group consisting of lower alkyl, fluorinated lower alkyl and monocyclic cycloalkyl-(lower alkyl)-; alternatively R 2 and R 1 are taken together as R 3 is phenyl; wherein the phenyl is optionally substituted with a substituent selected from the group consisting of halogen and fluorinated lower alkyl; R 4 is selected from the group consisting of benzyl, 4-fluoro-benzyl, 3,4-difluoro-benzyl, 3-chloro-4-fluoro-benzyl, 4-difluoromethyl-benzyl, 3-trifluoromethyl-benzyl, 4-trifluoromethyl-benzyl, 3-trifluoromethoxy-benzyl, 4-trifluoromethoxy-benzyl, 3-fluoro-4-trifluoromethyl-benzyl, 3-trifluoromethyl-4-fluoro-benzyl, 2-fluoro-5-trifluoromethyl-benzyl and 4-trifluoromethyl-thio-benzyl; provided that when a is 0, R 1 is methyl, R 2 is hydrogen and R 4 is methyl; then R 3 is other than methyl, phenyl, or 4-methylphenyl; or pharmaceutically acceptable salt thereof.