2,3-diketopiperazine derivatives or their salts

摘要

The present invention relates to a 2,3-diketopiperazine derivative or a salt thereof, which has inhibitory effect on platelet aggregation because of glycoprotein IIb/IIIa receptor antagonism and hence is useful as a prophylactic and therapeutic agent for diseases associated with platelet aggregation. General formula wherein R1 represents a protected or unprotected amidino group; R2 represents a hydrogen atom or a carboxyl-protecting group; A represents a substituted or unsubstituted lower alkylene group; B represents -O-, -CONH-, -NHCO- or -SO2NH-; Y represents a substituted or unsubstituted lower alkylene group; and the broken line represents a single bond or a double bond.