Patent ID: 7153874

Claim:
A compound of formula I wherein R 1 is C 1 –C 6 alkyl; R 2 is C 1 –C 6 alkyl or C 3 –C 12 cycloalkyl; R 3 is aryl that is unsubstituted or substituted by one, two or three substituents selected from halogen, C 1 –C 6 alkyl, S—C 1 –C 6 alkyl, C 1 –C 6 alkyl-halogen, C 1 –C 6 alkoxy, halogen-C 1 –C 6 alkoxy, C 3 –C 12 cycloalkyl, C 1 –C 6 alkylamino, di-C 1 –C 6 alkylamino, C 1 –C 6 alkoxyamino, (C 1 –C 6 alkoxy)C 1 –C 6 alkylamino, C 3 –C 12 cycloalkylamino, benzylamino and cyano; and R 4 is hydrogen, C(O)H or CH 2 R 5 wherein R 5 is hydrogen, OH, C 1 –C 6 alkyl or C 3 –C 12 cycloalkyl or a pharmaceutically acceptable salt thereof.