Patent ID: 8012982

Claim:
The compound of formula (Ia) or a pharmaceutically acceptable salt thereof: wherein R 4 is C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, (CH 2 ) 0-3 C 3-8 cycloalkyl, C 1-6 alkoxy, (CH 2 ) 0-3 aryl, (CH) 2 aryl, (C 2 ) 0-3 Oaryl, (CH 2 ) 0-3 heteroaryl and (CH 2 ) 0-3 Oheteroaryl, optionally substituted by hydroxy, halogen, CN, CF 3 , C 1-4 alkyl, C 1-4 alkoxy, (CH 2 ) 0-3 NR 11 C(O)OR 12 , (CH 2 ) 0-3 aryl or (CH 2 ) 0-3 heteroaryl, where R 11 and R 12 are each independently hydrogen or C 1-6 alkyl; and R 15′ is CN, CF 3 , C 2-4 alkenyl, phenyl, OBn, C(O)C 1-4 alkyl, or C(O)phenyl.