Forging\n1,1′-Bicyclopropenyls by Synergistic\nAu/Ag Dual-Catalyzed Cyclopropenyl Cross-Coupling

1,1′-Bicyclopropenyl\nis a constitutional isomer of benzene\ncomprising two coupled cyclopropene units with the endocyclic double\nbonds in conjugation. Due to the intrinsic high strain energy, it\nremains a long-standing challenge to prepare 1,1′-bicyclopropenyl\nderivatives, particularly multisubstituted, nonsymmetrical ones, in\nan efficient and modular manner. Herein a straightforward Au/Ag bimetallic-catalyzed\ncyclopropenyl cross-coupling has been developed, providing a robust\nand versatile strategy for the rapid assembly of symmetrical and unsymmetrical\n1,1′-bicyclopropenyl derivatives from cyclopropenyl benziodoxoles\n(CpBXs) and terminal cyclopropenes. Advantages of this strategy include\ntolerance to a wide range of synthetically useful functional groups,\nmild reaction conditions, and a simple catalytic system. The obtained\n1,1′-bicyclopropenyl derivatives were shown to be valuable\nsynthetic intermediates through selective downstream manipulations.