Patent ID: 8183276

Claim:
A compound of formula I: or a pharmaceutically acceptable salt thereof; wherein: R 1 represents H, C 1-6 alkyl, C 3-6 cycloalkyl or C 2-6 alkenyl; R 2 represents C 1-6 alkyl, C 3-6 cycloalkyl or C 2-6 alkenyl; Het represents: W represents C═O or SO 2 ; each R 7 independently represents H or a substituent selected from: alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkylalkyl groups, all of up to 10 carbon atoms, phenyl, naphthyl, 5- or 6-membered heterocyclyl, halogen, CN, NO 2 , CF 3 , OR 4 , COR 4 , CO 2 R 4 , OCOR 3 , N(R 4 ) 2 , CON(R 4 ) 2 , SR 3 , SO 2 R 3 , and SO 2 N(R 4 ) 2 ; where said alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkylalkyl groups bear 0-1 substituents selected from halogen, CN, NO 2 , CF 3 , OR 6 , COR 6 , CO 2 R 6 , OCOR 5 , N(R 6 ) 2 , CON(R 6 ) 2 , SR 5 , S 2 R 5 , and SO 2 N(R 6 ) 2 ; and said phenyl, naphthyl and 5- or 6-membered heterocyclyl bear 0-3 substituents selected from halogen, CN, NO 2 , R 5 , OR 6 , COR 6 , CO 2 R 6 OCOR 5 , N(R 6 ) 2 , CON(R 6 ) 2 , SR 5 , SO 2 R 5 , and SO 2 N(R 6 ) 2 ; or two R 7 groups attached to adjacent ring atoms may together represent a fused ring system consisting of a phenyl or a 5- or 6-membered heteroaryl ring which is optionally fused to a further 5- or 6-membered carbocyclic or heterocyclic ring, said fused ring system bearing 0-3 substituents selected from halogen, CN, NO 2 , R 3 , OR 4 , COR 4 , CO 2 R 4 , OCOR 3 , N(R 4 ) 2 , CON(R 4 ) 2 , SR 3 , SO 2 R 3 , and SO 2 N(R 4 2 ; and R 8 represents H, C 1-6 alkyl, C 3-6 cycloalkyl, C 3-6 cycloalkyl,C 1-4 alkyl, phenyl or benzyl wherein said phenyl and benzyl bear 0-2 substituents selected from halogen, CF 3 and C 1-4 alkyl; R 3 represents C 1-6 alkyl, C 3-6 cycloalkyl, c 2-6 alkenyl, phenyl, benzyl or CF 3 ; R 4 represents H or R 3 or two R 4 groups attached to the same nitrogen atom optionally complete a heterocyclic group of up to 7 ring atoms which bears 0-3 substituents selected from halogen, CF 3 , C 1-4 alkyl, C 1-4 alkoxy and C 1-4 alkoxycarbonyl; R 5 represents C 1-6 alkyl, phenyl or CF 3 ; and R 6 represents H or R 5 or two R 6 groups attached to the same nitrogen atom optionally complete a heterocyclic group of up to 7 ring atoms which bears 0-3 substituents selected from halogen, CF 3 , C 1-4 alkyl, C 1-4 alkoxy and C 1-4 alkoxycarbonyl.