Carbene-Protected Copper Nanocluster for Highly Efficient Difunctionalization of C(sp 2 )–H and O–H Bonds

The difunctionalization of C(sp 2 )–H and O–H bonds represents an important and efficient way to directly form C–C and C–O bonds simultaneously, but achieving high site-selectivity, chemoselectivity, and turnover number is a significant challenge. Here, we prepare a stable copper cluster (Cu 3 NC (NHC) ) with two attributes, rigidity and flexibility. The Cu 3 NC (NHC) catalyst has been successfully used to catalyze the difunctionalization reaction with high site-selectivity and chemoselectivity, which represented a significant advancement in copper catalysts for catalyzing the C(sp 2 )–H and O–H bonds. As expected, the turnover number was elevated to 126,000, and the turnover frequency reached 445 h –1 in the difunctionalization reaction. Mechanistic studies and density functional theory illustrate that the property of the Cu 3 NC (NHC) -carbenoid may be closer to that of a Cu 3 NC (NHC) -stabilized carbocation, thus providing difunctionalization products that are completely different from those of traditional copper catalysts. A proton shift model was found that the N atom of pyridine assisted in catalyzing proton shift. This work highlights the importance of copper clusters in cascade reactions, affords an efficient method to generate “carbophilic carbocations”, and provides a reference for the development of cluster organic catalysis.