Difluorocarbene as C Synthon and CF Synthon in Cycloadditions and Annulations

This review summarizes the progress in the application of difluorocarbene as a multifunctional fluorinated reagent in cyclization reactions via the cleavage of C–F bonds, with a focus on research since 2018. The contents are organized according to the functions exhibited by difluorocarbene, and reaction mechanisms are provided to illustrate the multifaceted roles of this important building block in various transformations by selective C–F bond cleavage, including its use as a C1 synthon or CF synthon.