N-Heterocyclic Carbene-Catalyzed Desymmetrization of Siladials To Access Silicon-Stereogenic Organosilanes

Abstract

An N-heterocyclic carbene (NHC)-catalyzed enantioselective monoesterification of silicon-centered dialdehydes with alcohols or phenols is accomplished, providing optically active organosilanes bearing a stereogenic center at the silicon atom. This desymmetrization protocol is suitable for scale-up synthesis and late-stage modifications of complex molecules, and the products can be further transformed to other enantiopure functionalized silanes.

Isothiourea-Catalyzed Acylative Desymmetrization of Silicon-Centered Bisphenols

“…Over the past several years, the groups of Zhao, Li, , Chi, and Wang have developed a number of elegant strategies to generate carbon, phosphorus, and sulfur stereocenters by discriminatively functionalizing one hydroxyl group of the two phenol moieties (Scheme d). Our laboratory is interested in exploring novel organocatalytic approaches to synthesize optically active compounds. , We envisioned that under the assistance of a proper ITU catalyst, the enantioselective monoacylation of silicon-centered bisphenols with anhydrides could also lead to the formation of a new chiral silicon center (Scheme e). However, to realize such an interesting chemical transformation, three main challenges must be addressed: (1) the chirality should be effectively induced from the ITU catalyst to the remote silicon center; (2) the similar groups on the silicon atom should be successfully distinguished; and (3) the undesired background reaction should be considerably minimized.…”