Difluorocarbene Chemistry: A Simple Transformation of 3,3-gem-Difluorocyclopropenes to Cyclopropenones

The cycloaddition reactions of α-acetyoxyl propynes with difluorocarbene, generated from the decomposition of FSO2CF2CO2SiMe3 in DG in the presence of 10% of NaF at 120 °C gave readily α-acetyoxyl gem-difluorocyclopropenes. When these fluorinated compounds were hydrolyzed under alkaline condition at 0 °C, α-hydroxyl cyclopropenones were produced predominantly whereas treated with catalytic amounts of BF3·Et2O in Et2O, α-acetyoxyl cyclopropenones were obtained.