2-氧代戊烷-1,5-二甲酸二乙酯

4'-benzyl-3-bromospiro[oxolane-2,2'-piperazine]-3',6'-dione

1-benzyl-3-(3-hydroxypropylidene)piperazine-2,5-dione

diethyl 2-[(2-chloroacetyl)amino]pent-2-enedioate

(Z)-1-benzyl-3-<2-(ethoxycarbonyl)ethylidene>-2,5-piperazinedione