Difluorocarbene Chemistry: Synthesis of gem-Difluorocyclopropenyl Ketones and gem-Difluorinated Dihydrofurans

The cycloaddition reactions of difluorocarbene, generated by the decomposition of FSO2CF2CO2SiMe3, with α,β-acetylenic ketones give gem-difluorocyclopropenyl ketones in good yields. Treatment of these gem-difluorocyclopropenyl ketones with aqueous potassium carbonate results in the formation of gem-difluorinated dihydrofurans.