The present invention relates to novel derivatives of general formula (I) ##STR00001## in which R3 is a (1 6C)alkyl, aryl, aryl(1 6C)alkyl, heteroaryl, heteroaryl(1 6C)alkyl, aryl or heteroaryl fused to a (1 10C)cycloalkyl, heterocycle, heterocycloalkyl, cycloalkyl, adamantyl, polycycloalkyl, alkenyl, alkynyl, CONR1R2, COOR1, SO.sub.2R1, C(.dbd.NH)R1 or C(.dbd.NH)NR1 radical; R5 and R6 are, independently of one another, chosen from the following radicals: halogen, CN, NO.sub.2, NH.sub.2, OH, COOH, C(O)OR8, --O--C(O)R8, NR8R9, NHC(O)R8, C(O)NR8R9, NHC(S)R8, C(S)NR8R9, SR8, S(O)R8, SO.sub.2R8, NHSO.sub.2R8, SO.sub.2NR8R9, --O--SO.sub.2R8, --SO.sub.2--O--R8, trifluoromethyl, trifluoromethoxy, (1 6C)alkyl, (1 6C)alkoxy, aryl, aryl(1 6C)alkyl, heteroaryl, heteroaryl(1 6C)alkyl, heterocycle, cycloalkyl, alkenyl, alkynyl, adamantyl or polycycloalkyl.