Patent ID: 7795457

Claim:
A compound having a structure represented by formula I or a pharmaceutically acceptable salt thereof, where R 1 is H or methyl; R 2 is methyl or ethyl; R 3 is H; R 4 and R 5 are independently, for each occurrence thereof, H, C 1 -C 8 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, CHR 7 R 9 , or (CHR 9 ) n R 8 , or R 4 and R 5 together with the nitrogen to which they are bonded combine to form with the proviso that R 5 can also be C(═O)NH 2 ; R 6 is H or C(═O)NR 4 R 5 ; R 7 is unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted cycloaliphatic, unsubstituted or substituted heterocycloaliphatic, CO 2 R 9 , cyano, or COR 9 ; R 8 is unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted cycloaliphatic, unsubstituted or substituted heterocycloaliphatic, NR 4 R 5 , CO 2 R 9 , OH, halo, cyano, OR 9 , or COR 9 ; R 9 is, independently for each occurrence thereof, H, OH or C 1 -C 5 alkyl; and n is, independently for each occurrence thereof, 2, 3, 4, 5, or 6.