Cu-catalyzed regioselective diborylation of 1,3-enynes for the efficient synthesis of 1,4-diborylated allenes

Borylation of 1,3-enynes with bis(boronate) compounds often ends up with the formation of hydroborylated products, leaving the diborylation of 1,3-enynes for the formation of 1,4-diborylated allenes to be challenging. Herein, a copper-catalyzed chemo-, regio-, and stereo-selective diborylation of 1,3-enynes for the efficient construction of 1,4-diborylated allenes under base-free conditions was reported. A wide range of 1,3-enynes bearing various functional groups can participant in the reaction and afforded the corresponding 1,4-diborylated allenes in good to excellent yields, which was enabled by the protocol of Bpin to BF3K conversion. the borylcopper species was supposed to selectively attack the C−C triple bond of the 1,3-enynes.