Double Stereodifferentiation in the Asymmetric Dihydroxylation of Optically Active Olefins

Abstract

A study of the stereochemical control on the asymmetric dihydroxylation of the double bond of optically active vinyl epoxides and their derivatives (bromo derivatives, azido derivatives, and vinyl aziridines) was carried out and the obtained results are herein reported. The most interesting results were obtained on trans α,β-unsaturated epoxy esters, which were successfully converted with a diastereomeric ratio >80% into the corresponding diols using either the matched or the mismatched conditions, depending on the ligand used. Unprotected bromo derivatives and unprotected aziridines did not afford significant results, while for the protected bromo derivatives, azido derivatives, and N-Boc protected aziridines the matched conditions led to a diastereomeric ratio >95%. Chirality 28:387-393, 2016. © 2016 Wiley Periodicals, Inc.

Catalyst‐Controlled Multicomponent Aziridination of Chiral Aldehydes

“…Less common are methods that display true catalyst control in setting the stereochemistry of new chiral centers independent of chiral centers already present in the molecule. Typically, one finds matched and miss‐matched pairs that allow for the selective formation of one of the possible diastereomers . In this report we describe the first catalyst‐controlled multicomponent asymmetric aziridination of aldehydes in which the absolute stereochemistry of the newly formed aziridine is a function of the catalyst and not of the chiral centers in the aldehyde present at either the α‐ or β‐positions (Scheme ).…”