Patent ID: 7511052

Claim:
A compound of formula I: wherein: R 1 is selected from the group consisting of C 1 to C 4 alkyl, C 1 to C 4 haloalkyl, heteroaryl, and â€”NR 5 R 6 wherein R 5 and R 6 are independently selected from the group consisting of hydrogen and C 1 to C 4 alkyl, or R 5 and R 6 together with the nitrogen atom pendent thereto form a heterocyclic ring; R 2 is selected from the group consisting of C 1 to C 4 alkyl, C 2 to C 4 alkenyl, and C 2 to C 4 alkynyl; and R 3 and R 4 are independently C 1 to C 3 alkyl or R 3 and R 4 together with the nitrogen atom pendent thereto join to form a heterocyclic ring; or a pharmaceutically acceptable salt; or an ester of the carboxylic acid alpha to the amino group thereof.