@article{oai:kanagawa-u.repo.nii.ac.jp:00002937,
 author = {辛, 重基 and Shin, Chung-gi and 佐藤, 憲一 and Sato, Ken-ichi and Ohtsuka, Akira and Mikami, Kazutoshi and 吉村, 寿次 and Yoshimura, Juji},
 issue = {12},
 journal = {Bulletin of the Chemical Society of Japan},
 month = {Dec},
 note = {A general synthetic route to unsymmetric 3,6-dialkylidene and 3-alkylidene-6-arylidene-2,5-piperazinediones is described. The condensation reaction of ethyl 2-oxocarboxylates with chloroacetamide in the presence of several acidic catalysts afforded N-chloroacetyldehydroamino acid esters. These compounds were cyclized in saturated ethanolic ammonia to give 3-monoalkylidene and benzylidene-2,5-piperazinediones (2). Compound 2 and 1-monoacetyl- or 1,4-diacetyl-3-alkylidene and benzylidene-2,5-piperazinediones, derived from a reaction of 2 with acetic anhydride, were condensed with alkyl and arylaldehyde in the presence of bases to afford 5., Article},
 pages = {3876--3880},
 title = {α,β-Unsaturated Carboxylic Acid Derivatives. IV. General Synthesis of Unsaturated Unsymmetric 3,6-Disubstituted-2,5-piperazinediones},
 volume = {46},
 year = {1973}
}