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Review | Regular issue | Vol 20, No. 7, 1983, pp.1407-1433
Published online, 1st January, 1970
DOI: 10.3987/R-1983-07-1407
Stereoselective Synthesis of the Geometric and Optical Isomers of Unsaturated 3-Mono- and 3,6-Disubstituted 2,5-Piperazinediones

Chung-gi Shin

*Departmnet of Applied Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

Abstract

Four kinds of naturally occurring 3,6-dibenzylidene (1)-, 3-(p)-anisilidene-6-benzylidene (2), -3-isobutylidene-6-benzylidene (3; antibiotic albonoursin)-, and 3-benzyl-6-benzylidene-2,5-piperazinediones (4), isolated from Streptomyces and Actinomyces strains, and their possible geometric and optical isomers were stereoselectively synthesized. Based on the spectral data and the independent preparation, the configuration and conformation of the natural products 1, 2, and 3 could be clearly determined to be (3Z, 6Z)-isomers and 4 to be (3R, 6Z)-isomer. Particularly, from the NMR and CD spectral data, the useful criterion for the configurational determination of the geometry of exocyclic C=C bond was obtained and the conformation of the half boat structure of 2,5-piperazinediones was unambiguously confirmed. Moreover, the methylation of 1, 2, and 3 was achieved to give mainly three kinds of derivatives, 1-, 4-mono-, and 1,4-dimethylated 1, 2, and 3 respectively.