| abstract |
Compounds of the general formula (I), or pharmacologically acceptable salts, esters, or other derivatives thereof, exhibiting excellent immunosuppressive activities wherein R1 and R2 are each hydrogen or an amino-protecting group; R3 is hydrogen or a hydroxyl-protecting group; R4 is lower alkyl; n is an integer of 1 to 6; X is ethylene; Y is C1-10 alkylene which may be mono- to tri-substituted with one to more members selected from groups a and b of substituents; R5 is aryl; and R6 and R7 are each hydrogen or a member select ed from group a of substituents, with the proviso that when R5 is hydrogen, Y i s a group exclusive of single bond and linear C1-10 alkylene. |