Pd/Cu Cooperative Catalysis for Heteroarylation of Vinyl C–H Bond Forming Polyaryl Ethylenes via C–O/Dual C–H Cleavage

Abstract

Polyaryl ethylenes find wide applications in synthetic, medicinal, and material fields; however, their stereoselective synthesis is very challenging. In this paper, we describe a highly efficient bimetallic cooperative catalysis consisting of a palladium catalyst and a copper catalyst. This catalytic system enables the stereo-selective installation of a heteroaryl group onto the double bond of ortho-vinyl phenoxides via C−O cleavage and dual C−H activation. Extensive mechanistic studies show that copper-catalyzed C−H cleavage of heteroarenes is the ratedetermining step. It can facilitate the formation of the key intermediate palladium cycle along with the ionic properties of arylpalladium species generated through oxidative addition, thus promoting the shift of Pd from the aryl to the vinyl group and ensuring the success of this reaction. This reaction overcomes the substrate limitation of previous aryl halide-based palladium shift systems well and provides an efficient method for preparing polyaryl ethylenes with high stereo-selectivity and a wide substrate scope. cis-Diaryl ethylenes, trans-diaryl ethylenes, triaryl ethylenes, and tetraaryl ethylenes all can be produced stereo-selectively. Considering the unique chemical and physical properties of poly-substituted ethylenes, especially the strong AIE effect, we anticipate that this powerful synthetic strategy will find wide applications in synthetic and material communities.