Generation of difluorocarbenes and introduction of fluorinated one carbon units into carbonyl and related compounds

Difluorocarbene is a simple and versatile one-carbon unit for synthesizing acyclic and cyclic organofluorine compounds. However, the use of difluorocarbene in organic synthesis has been relatively limited because of the harsh conditions required for its generation, the toxicity of the precursors, and undesired dimerization. This feature article provides an account of (i) the generation of free and metal difluorocarbenes from trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate (TFDA) or BrCF2CO2Li/Na and (ii) their application to the facile synthesis of valuable organofluorine compounds. The difluorocarbenes thus generated react with (thio)carbonyl compounds and silyl dienol ethers to provide a wide variety of products such as (a) difluoromethyl (thio)ethers, (b) fluorinated thiophenes, (c) fluorinated thia/oxazoles, (d) fluorinated cyclopentanones and (e) difluoroalkenes.