The cyclization reaction of D-aspartic acid was studied, the carboxyl groups of D-aspartic acid were protected by benzyl alcohol to give compound D-dibenzyl aspartate. Then (4R)-benzyl azetidine-2-one-4-carboxylate and meso-3,6-disubstituted piperazine2,5-diones were synthesized via intramolecular cyclization and intermolecular cyclization of D-dibenzyl aspartate, respectively, and their structures were confirmed by H-1 NMR and MS. Both cyclization reaction conditions were also investigated in detail. (c) 2007 Si Ping Pang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.