Pd(II)-Bipyridine Catalyzed Conjugate Addition of Arylboronic Acid to α,β-Unsaturated Carbonyl Compounds

[Reaction: see text]. A Pd(II)-catalyzed conjugate addition of arylboronic acid to alpha,beta-unsaturated ketones, aldehydes, esters, etc. in the presence of 2,2'-bipyridine was developed. A mechanism involving transmetalation, insertion of the carbon-carbon double bond into the C-Pd bond, and protonolysis of the resulting C-Pd bond is proposed. The reaction conditions are mild and the yield is high. The presence of 2,2'-bipyridine is crucial for the reaction to inhibit beta-hydride elimination.