Difluorocarbene Generation via a Spin-Forbidden Excitation under Visible Light Irradiation.

The generation of difluorocarbene from difluoromethane bis(sulfonium ylide) through spin-forbidden excitation under irradiation with 450 nm blue light was reported. The formation of difluorocarbene was confirmed by its reaction with styrene derivatives for the generation of difluorocyclopropanation and insertion into RX-H bonds (X = O, S) for the generation of RXCFH. The spin-forbidden excitation mechanism for the formation of difluorocarbene from difluoromethane bis(sulfonium ylide) was supported by spectroscopic and kinetic studies as well as computational chemistry.