Asymmetric Partial Hydrosilylation of 2,2‐Difluoro‐1,3‐diketones with Chiral Frustrated Lewis Pairs

Abstract

Comprehensive SummaryThe asymmetric partial reduction of 1,3‐diketones stands as a straightforward pathway to access optically active β‐hydroxyketones. In this paper, an asymmetric Piers‐type hydrosilylation of 2,2‐difluoro‐1,3‐diketones was successfully realized by using a frustrated Lewis pair of chiral borane and tricyclohexylphosphine as a catalyst, delivering a variety of α,α‐difluoro‐β‐hydroxyketones in high yields with up to 99% ee. Significantly, no over‐reduced diol products were observed even with an excess amount of silanes. The product can be conveniently converted to α,α‐difluoro‐β‐hydroxyester or 1,3‐anti‐diol via an oxidation with m‐CPBA or a reduction with DIBAL‐H without obvious loss of ee.