Patent ID: 6960575

Claim:
A compound represented by the following formula [I] or a salt thereof, wherein X is S, R 1 and R 2 , being the same or different, are hydrogen, lower alkyl, cycloalkyl or aryl, R 3 and R 4 , being the same or different, are hydrogen, lower alkyl, cycloalkyl, aryl or an aromatic heterocycle, R 5 is hydrogen, lower alkyl, cycloalkyl, aryl or -A 3 -A 4 -R 7 , R 7 is hydrogen, lower alkyl, hydroxy, lower alkoxy, aryl, aryloxy, amino, lower alkylamino, arylamino, an aromatic heterocycle or a nonaromatic heterocycle, A 1 is lower alkylene, A 3 is lower alkylene, A 4 is carbonyl or oxalyl, each lower alkyl defined above is unsubstituted or substituted by halogen, hydroxy, lower alkoxy, aryl or aryloxy, each lower alkoxy defined above is unsubstituted or substituted by aryl, and each lower alkylene defined above is unsubstituted or substituted by aryl.