Microwave-Assisted Ligand-Free Nickel-Catalyzed β-Boration of α,β-Unsaturated Carbonyl Compounds with Bis(pinacolato)diboron

A simple and efficient ligand-free nickel-based catalytic system has been developed for the beta-boration of alpha,beta-unsaturated carbonyl compounds with bis(pinacolato)diboron. With catalyst loading of 10-15 mol%, a series of beta-boration products from chalcones and cinnamates was obtained rapidly in moderate to excellent yields within 3-30 minutes under a nitrogen atmosphere and microwave irradiation. The combination of hydroboration with microwave irradiation provided a convenient and rapid method to afford a boronate group at the beta-position of carbonyl.