Ligand-Free Nickel-Catalysed 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Carbonyl Compounds

A simple and efficient ligand-free nickel-based catalytic system has been developed for the 1,4-addition of arylboronic acids to alpha,beta-unsaturated carbonyl compounds. With catalyst loadings of 12 mol%, a series of 1,4-adducts from chalcones and cinnamates was obtained in moderate to excellent yields within 5-30 min under a nitrogen atmosphere and microwave irradiation. The 1,4-addition of arylboronic acids to acrylates is less efficient.