compounds containing one to four nitrogen atoms react with chlorodifluoromethane in the presence of concentrated aqueous sodium hydroxide and a catalyst, benzyltriethylammonium chloride (TEBAC) in dichloromethane or THF (phase-transfer catalysis, PTC) with formation of N-difluoromethyl substituted derivatives. The process takes place by reaction of N-anions from these heterocycles with difluorocarbene and
An expedient approach to the difluoromethylation of imidazoles and benzimidazoles has been developed. The key feature of the procedure is the gradual generation of the difluoromethylation reagent in the reaction mixture, which is achieved by the simultaneous addition of chlorodifluoromethane and alkali. The method is applicable to functionalized substrates and allows the corresponding 1-(difluoromethyl)imidazoles and -benzimidazoles to be prepared in 60-95% yield on a hundred-gram scale.