Chiral Boronate Derivatives via Catalytic Enantioselective Conjugate Addition of Grignard Reagents on 3-Boronyl Unsaturated Esters and Thioesters

There is a growing interest in the development of new methods to prepare chiral organoboronate derivatives in optically pure form. An efficient copper-catalyzed enantioselective conjugate addition methodology using Grignard reagents and 3-boronyl acrylate derivatives was optimized for the preparation of chiral alkylboronate products in high yields and up to 98% ee. The resulting 1,8-diaminonaphthalene adducts can be transformed into the corresponding boronic acid, pinacol boronate, and trifluoroborate salt. This method extends the realm of chemical reactions compatible with useful boron-containing substrates.