Copper Nanoclusters with Exposed Active Sites for Highly Efficient Protoboration of C-C Multiple Bonds.

Although atomically precise metal nanoclusters bridge homogeneous and heterogeneous catalysis, their application in the protoboration of C-C unsaturated bonds remains challenging. Herein, we report a stable copper nanocluster (Cu6-1) featuring exposed active sites, which successfully enables efficient protoboration of alkynes. This catalyst can be readily synthesized on a gram scale and exhibits ultrahigh catalytic efficiency under ambient conditions (room temperature and air atmosphere), achieving a turnover number (TON) of up to 32,000. The reaction demonstrates excellent regio- and stereoselectivity, and the substrate scope has been successfully expanded to alkenes and enynes. More importantly, Cu6-1 overcomes the recyclability issues of traditional catalysts, retaining its activity over eight consecutive cycles with no significant deactivation, thus offering a highly efficient and robust platform for the synthesis of organoboron compounds.