Stereoselective preparation of β-aryl-β-boronyl enoates and their copper-catalyzed enantioselective conjugate reduction.

A new methodology has been developed for the stereoselective preparation of β-aryl-β-boronyl α,β-unsaturated esters via Heck coupling, and their subsequent copper(I)-catalyzed enantioselective conjugate reduction. Various chiral secondary boronate derivatives can be accessed in excellent yields and good to high levels of enantioselectivity through the efficient copper-catalyzed process using polymethylhydrosiloxane (PMHS) as the hydride source.