Asymmetric Synthesis of 2H-Azirine 2-Carboxylate Esters.
2H-Azirine 2-carboxylate esters (5), the smallest unsaturated nitrogen heterocycle, are readily prepared in enantiomerically pure form via the base-induced elimination of sulfenic acid (RSOH) from nonracemic N-sulfinylaziridine 2-carboxylate esters (4). Optimum yields were obtained when the aziridine was treated with TMSCl at -95 degrees C followed by LDA, which was attributed to the improved leaving group ability of an silicon-oxonium species. By using this new methodology the first asymmetric syntheses of the marine cytotoxic antibiotics (R)-(-)- and (S)-(+)-dysidazirine (2) were accomplished.
Davis
Franklin A.
FA
Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122.
Liu
Hu
H
Liang
Chang-Hsing
CH
Reddy
G. Venkat
GV
Zhang
Yulian
Y
Fang
Tianan
T
Titus
Donald D.
DD