Hydroboration and Diboration of Internal Alkynes under Iridium Catalysis
Huan Ding1, Weiwei Gao1, Tian Yu1
1State Key Laboratory of Organic-Inorganic Composites, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Abstract:
Here we demonstrate the feasibility and efficiency of simple iridium-based catalytic systems in the synthesis of multisubstituted alkenyl boronates from internal alkynes with high selectivities. A variety of alkynes were smoothly decorated with HBpin under a mild [Ir(cod)Cl]2/dppm/acetone condition to afford trisubstituted alkenyl boronic esters with up to >99:1 regioselectivity. The diboration reaction could effectively occur in the presence of [Ir(cod)Cl]2/DCM. Plausible mechanisms were provided to illustrate these two catalytic processes, in which the intrinsic functional group of the alkyne was supposed to be important in facilitating these reactions as well as the regioselectivity.
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