An Organocatalytic β-Boration of α,β-Unsaturated Carbonyl Compounds

Significance

The authors report a chiral phospine-1-catalyzed β-boration of α,β-unsaturated carbonyl compounds using (Bpin)₂ as borylating agent. The products were obtained in high conversions and optical purities. The mechanistic rationale is based on the phosphine coordination to one of the boron atoms, inducing a high polarization and presumably partial dissociation of the B-B bond. Thus, the potentially more nucleophilic boron atom could as such add to the double bond of the substrate in a phosphine-mediated chiral environment. Alcoholysis of the intermediate can then liberate the product and the boronic acid ester byproduct.