Stereoselective Control of the Cu Activation of β,β-Diboryl Acrylates for Allylic Coupling Protocols with Concomitant Lactonization.

The key to a successful C-B activation is to discriminate between two geminal boryl moieties that are exposed to the same reaction conditions. Here we describe a stereoselective C-B activation of β,β-diboryl acrylates forming exclusively the ( Z )-α-borylalkenyl copper(I) key intermediate, for subsequent allylic alkylation reactions. The new borylated ( Z )-skipped dienoates followed a feasible iodo-lactonization sequence for the preparation of borylated lactone cores, which can be used in drug discovery.