Chemistry of Oxaziridines. 3. Asymmetric Oxidation of Organosulfur Compounds Using Chiral 2-Sulfonyloxaziridines

Abstract

Chiral 2-sulfonyloxaziridines, 9–12, afford the best enantioselectivity of any chiral oxidizing reagent for the asymmetric oxidation of sulfides and disulfides to sulfoxides and thiosulfinates, respectively, 5–8 times better than chiral peracids. For asymmetric oxidations using 9–12, the configuration of the oxaziridine three-membered ring was shown to control the configuration of the product, which could be predicted using a chiral recognition mechanism (Figure 2). The increased asymmetric bias exhibited by chiral 2-sulfonyloxaziridines was attributed to the fact that the active-site oxygen was incorporated into a rigid chiral environment. The group size difference (GSD) effect in both the oxaziridine and substrate play important roles in determining the absolute configuration of the product and the magnitude of the asymmetric bias. As the GSD increases the enantioselectivity increases. © 1982, American Chemical Society. All rights reserved.