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

Polyaryl
ethylenes find wide applications in synthetic, medicinal,
and material fields; however, their stereo-selective
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 rate-determining 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.