Patent ID: 7122680

Claim:
A compound of formula I: wherein: R 1 is H, CN, halo, C 1 –C 6 alkyl, C 1 –C 4 haloalkyl, CO 2 R 8 , CONHR 8 , NHCOR 8 , NHR 8 , OR 8 , SR 8 , SOR 8 , SO 2 R 8 or SO 2 NHR 8 ; R 1a is H, halo or C 1 –C 6 alkyl; R 2 is H, C 1 –C 6 alkyl or benzyl; R 3 is C 1 –C 6 alkyl or benzyl; provided that if R 3 is C 2 –C 6 alkyl or benzyl, then R 2 must be hydrogen; R 4 is H or C 1 –C 6 alkyl; R 5 and R 6 are independently H or C 1 –C 6 alkyl; R 7 is hydrogen, optionally substituted phenyl or optionally substituted heterocycle; R 8 is H or C 1 –C 6 alkyl; X is OCH 2 , SCH 2 or a bond; and X 1 is a bond or a C 1 –C 5 divalent hydrocarbon moiety; and X 2 is O, S, NH, NHSO 2 , SO 2 NH, CH 2 or a bond; or a pharmaceutical salt thereof.