Gold and Bismuth Trimetallic Synergistic Redox Catalysis for Non-Directed C─H Arylation with Aryl Bismuth.

The influence of substituent effects plays an important role on the efficiency and regioselectivity toward C─H activation of non-directed arenes. Here, an unprecedented trimetallic synergistic redox catalysis system has been developed to achieve a highly efficient and orthogonal C─H arylation of non-directed arenes with aryl bismuth. Both electron-rich and -deficient aryl bismuth can proceed C─H arylation readily, thus affording an elegant strategy for the synthesis of challenging electron-rich and sterically hindered biaryls by means of gold catalysis. Mechanistic studies reveal that Bi(V) species generated in-situ from Ar─Bi(III) and NFSI is not only an arylation reagent but also an oxidant to form a critical Au(II)─Au(II)─Bi intermediate (detected by HRMS). Interestingly, the binding Bi-moiety can modulate the electronic and steric environment of gold center through cooperative interactions, thus promoting the intramolecular transmetallation and reductive elimination. In addition, the synthetic robustness of this protocol has been demonstrated by gram-scale experiments and late-stage functionalization of complex molecules.