2 H-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° C followed by LDA, which was attributed to the improved leaving group ability of an silicon-oxonium species. By ...