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.