Lithium alkyl(hydro)dipinan-3α-ylborates. New reagents for asymmetric reduction of ketones

Abstract

The preparation and characterisation of a new class of reducing agents, lithium alkyl(hydro)dipinan-3α-ylborates, is described. These reagents have been used to reduce a series of ketones (of the type RCOR′) to optically active alcohols with optical yields in the range 5–45%. The stereochemistry of reduction of a series of substituted cyclohexanones is discussed.