Copper-Catalyzed Asymmetric Borylation: Construction of a Stereogenic Carbon Center Bearing Both CF3 and Organoboron Functional Groups.

Abstract

Copper-catalyzed borylation of β-trifluoromethyl-α,β-unsaturated ketones was efficiently achieved by means of bis(pinacolato)diboron (B2pin2), affording the enantioenriched products in good yields with high enantioselectivities. CuI and (R,S)-Josiphos consist of the most efficient catalyst system under mild conditions. In the absence of the chiral ligand, the reactions could be performed more efficiently to form β-ketone derivatives which were directly borylated and indirectly trifluoromethylated at the β-carbon atom of the α,β-unsaturated ketone substrates. The present protocol provides a promising method to access a stereogenic carbon center bearing both CF3 and organoboron functional groups.