Palladium-catalyzed reaction of boronic acids with chiral and racemic α-bromo sulfoxides

Palladium-catalyzed cross-coupling reactions of racemic α-bromo sulfoxides with boronic acids are carried out in either aqueous or nonaqueous medium with formation of a new C sp³-C sp² bond. The arylation of chiral α-bromo sulfoxides occurs without racemization. The cross-coupling reaction is general and gives high yields with arylboronic acids substituted with either donor or acceptor groups but gives poor results with heteroarylboronic acids. The best yields are obtained using degassed solvents and CsF instead of aqueous base. The use of aqueous base and the presence of oxygen favor the homocoupling side reaction.