Reductive Catalytic Difluorocarbene Transfer via Palladium Catalysis
Xue‐Ying Zhang, Xue‐Ying Zhang, Shi‐Ping Sun, Yueqian Sang, Xiao‐Song Xue, Qiao‐Qiao Min, Xingang Zhang, Xingang Zhang
Abstract
Abstract A palladium‐catalyzed reductive difluorocarbene transfer reaction that tames difluorocarbene to couple with two electrophiles has been developed, representing a new mode of difluorocarbene transfer reaction. The approach uses low‐cost and bulk industrial chemical chlorodifluoromethane (ClCF 2 H) as the difluorocarbene precursor. It produces a variety of difluoromethylated (hetero)arenes from widely available aryl halides/triflates and proton sources, featuring high functional group tolerance and synthetic convenience without preparing organometallic reagents. Experimental mechanistic studies reveal that an unexpected Pd 0/II catalytic cycle is involved in this reductive reaction, wherein the oxidative addition of palladium(0) difluorocarbene ([Pd 0 (L n )]=CF 2 ) with aryl electrophile to generate the key intermediate aryldifluoromethylpalladium [ArCF 2 Pd(L n )X], followed by reaction with hydroquinone, is responsible for the reductive difluorocarbene transfer.