Highly efficient phenalenyl–copper bifunctional photoredox catalyst for direct C–H bond arylation of arenes and heteroarenes

Abstract

Direct C–H arylation of arenes and heteroarenes emerges as a powerful and efficient synthetic method for the construction of challenging C–C bonds in organic chemistry. Here, we introduce a phenalenyl (PLY)-based copper–bipyridine (BPY) heteroleptic complex with the formula [(BPY)Cu^II(O,O-PLY-Ph)Cl] (1) as a cheap and efficient photocatalytic system for the blue light-mediated direct C–H bond arylation of arenes and heteroarenes using aryldiazonium salts. A wide range of arenes and heteroarenes were arylated using the present protocol in the absence of any promoter. Along with 1-catalyzed C–H arylations, the crucial role of each component in this catalytic reaction was established by combining structural, electrochemical, spectroscopic, theoretical, and mechanistic studies. Both the copper center and PLY unit in 1 play pivotal roles in the electron-transfer mediated dissociation of the aryldiazonium salt and activation of the arene partner, leading to the C–H arylation of the unbiased arene substrates.