Starting from Di- and Trifluoromethyl Compounds

The difluoromethylene ylides react with carbonyl derivatives (aldehyde, lactone) to afford gem-difluoromethylene compounds.They are generated starting from halogenodifluoromethane with triphenylphosphine (or trisaminophosphine) or starting from zinc and a phosphonium salt (or a phosphine oxide). °  

The radical addition of Cp2Br2 on olefins (activated or not) leads to difluorobro-momethyl and difluoromethyl compounds.  

Difluorocarbene, generated from fluorosulfonyldifluoroacetate, adds on double bonds and aromatic or vinylic ketones, affording fluorinated cyclopropanic ethers.  

Difluoroethylene and trifluorobromoethylene are also starting molecules to access difluorinated molecules through organometallic approaches (e.g., metallation, palladium-catalyzed coupling) vide infra) 

2 Starting from Halogenodifluoroacetic Acids Ethyl chloro-, bromo-, and iododifluoroacetates, as well as the corresponding difluorophosphonates, are powerful reagents for difluoromethylenation through radical, anionic, and elec-trophihc pathways. 

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