Patent ID: 6846953

Claim:
A compound of formula I wherein R 1 is hydrogen, C 1 -C 4 alkyl, or C 2 -C 4 alkenyl; R 2 and R 3 independently are hydrogen, C 1 -C 4 alkyl, phenyl or benzyl; X is (CH 2 ) n , CHMe-(CH 2 ) n-1 or (CH 2 ) n-1 —CHMe, n is 1, 2 or 3; R 4 is an aromatic or heteroaromatic group selected from wherein R 5 is hydrogen, halogen, C 1 -C 4 alkyl, nitro, N 3 or CF 3 and R 6 is hydrogen, C 1-4 alkyl, — and the pharmaceutically acceptable salts thereof, with the proviso that in formula I: when R 1 is H, (X) n is (CH 2 ) 2 and R 2 and R 3 are both ethyl, R 4 is not benzyl, 4-methylbenzyl, 4-chlorobenzyl, 2-chlorobenzyl, 4-bromobenzyl, 3-ethylbenzyl, 4 isopropylbenzyl, 4-n-propylbenzyl, 3-n-butylbenzyl, 2-t-butylbenzyl, 4-s-butylbenzyl or 2-bromobenzyl; when R 1 is H, (X) n is CH r and R 4 is benzyl, NR 2 R 3 is not NHCH 2 Ph, NH-t-butyl, N(CH 3 ) 2 or N(CH 2 CH 3 ) 2 ; and when R 1 is n-butyl, (X) n is (CH 2 ) 2 and R 4 is benzyl, NR 2 R 3 is not NHCH 2 Ph.