Readily Synthesized Chiral Sulfides as Reagents for Asymmetric Epoxidation

• Published in: Chemistry, an Asian journal Vol. 1; no. 3; pp. 438 - 444
• Main Authors: Badine, D. Michael, Hebach, Christina, Aggarwal, Varinder K.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 18-09-2006; WILEY‐VCH Verlag
• Subjects: asymmetric synthesis; chiral sulfides; epoxidation; sulfur ylides; synthesis design
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200600079

Chiral oxathianes were designed, synthesized, and successfully used for asymmetric sulfur ylide mediated epoxidation. A considerable emphasis has been placed upon the design of sulfides with suitable architecture in a small number of steps (three or four). The use of (4aR,6S,8aR)‐6‐isopropenyl‐8a‐methyloctahydro‐1,4‐benzoxathiane in asymmetric epoxidation resulted in good diastereo‐ and enantioselectivity in the formation of stilbene oxide, and (2S,6S)‐2‐allyl‐2,3,3,6‐tetramethyl‐1,4‐oxathiane produced even better results. Moderate to good diastereoselectivities with essentially complete enantioselectivities were observed in the formation of alkyl–aryl‐, vinyl–aryl‐, and propargyl–aryl‐substituted epoxides. The selectivities were rationalized and supported by density functional theory calculations.
Proof of principle: Based on our established model for the origin of enantiocontrol in sulfur ylide reactions with aldehydes, a number of chiral sulfides have been designed, efficiently synthesized, and tested in epoxidation. Not only do they lead to epoxides with high diastereo‐ and enantioselectivity, they also provide further experimental proof of the validity of the model.