ИСТИНА

The importance of gem-difluorinated compounds for medicinal chemistry has stimulated intensive studies for the synthesis of compounds of this type. Besides classic approaches based on deoxofluorination and the application of building blocks, the use of difluorocarbene and related reagents has recently emerged as an attractive method for the straightforward access to CF2-substituted products. A combination of (bromodifluoromethyl)trimethylsilane (Me3SiCF2Br), triphenylphosphine, and N,N′-Dimethylpropyleneurea (DMPU) serves as a source of difluorinated phosphorus ylide 1 under mild conditions. The system was used to effect nucleophilic difluoromethylation of ketones, nitroalkenes1 and acyl chlorides.2 gem-Difluorinated phosphonium adducts were hydrolyzed, afford- ing difluoromethylated products 2. Difluorinated phosphorus ylide 1 can also be generated via thermal decarboxylation of the difluoromethylene phosphobetaine 3. Ylide 1 was trapped by halogenating reagents, as well as arylsulfenyl and arylselenyl chlorides3 affording difluorinated phosphoni- um salts 4. The crystal structures of the salts 4 were studied by X-ray diffraction analysis.