Stereo- and Regioselective Cu-Catalyzed Hydroboration of Alkynyl Chalcogenoethers

A mild stereo- and regioselective Cu-catalyzed hydroboration method for the synthesis of (Z)-seleno-alkenyl boronates and (Z)-thio-alkenylboronates from internal alkynes in the presence of commercially available B(2)pin(2) is presented. This highly selective transformation relies on the use of N-heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give alpha-chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen-containing molecules.