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Communication | Regular issue | Vol 36, No. 6, 1993, pp.1205-1208
Published online, 1st January, 1970
DOI: 10.3987/COM-92-6324
An Approach to Optically Active Pyrrolizidines by an Intramolecular Michael Reaction

Tatsunori Sato, Ken-ichiro Matsubayashi, Katsuhiro Tsujimoto, and Masazumi Ikeda*

*Kyoto Pharmaceutical University, Misasagi-Shichonocho, Yamashina, Kyorto 607-8414, Japan

Abstract

Treatment of a diastereomeric mixture (5:3) of the α-phenylsulfinylacetamide (3) with a catalytic amount of sodium ethoxide in ethanol at 0 °C for 10 min gave the bicyclic lactams (4a) and (4b) in high total yield but with extensive racemization. The cyclization of the diastereomerically pure sulfoxide (3) followed by chromatographic separation of the resulting lactams (4a) and (4b) and desulfurization of each lactam gave (1S,8S)-(-)- and (1R,8R)-(+)-ethyl hexahydro-3-oxo-3H-pyrrolizin-1-ylacetates (6), respectively. The (-)-isomers of 6 has already been transformed into (-)-trachelanthamidine (8).