Patent ID: 7491723

Claim:
A compound of formula I; or a pharmaceutically salt thereof; wherein; W is OR 9 ; R 1 and R 2 are, independently, H, OH, alkyl, alkoxy, halo, trifluoromethyl, alkanoyloxy, or together form, methylenedioxy; R 5 is H or (C 1 -C 6 )alkyl; R 6 and R 7 are, independently, (C 1 -C 6 )alkyl or (C 3 -C 6 )cycloalkyl; R 8 is H or (C 1 -C 6 )alkyl; R 9 is H, (C 1 -C 4 )alkyl, or (C 1 -C 4 )alkyl-C(═O); t is 1, 2, or 3; and x is 1.