Copper-Mediated, Palladium-Catalyzed Coupling of Thiol Esters with Aliphatic Organoboron Reagents

Thiol esters and B-alkyl-9-BBN derivatives couple in the presence of a copper(I) carboxylate mediator and a palladium catalyst. In contrast to copper-mediated, palladium-catalyzed cross-couplings of thioorganics with boronic acids, the current coupling reaction of 9-BBN derivatives is facilitated by the addition of a base such as Cs2CO3. Under optimized conditions, a variety of thiol esters react with different B-alkyl-9-BBN derivatives giving ketones in moderate to excellent yields.