A facile synthesis of difluoromethylene compounds by oxidative fluorodesulfurization of dithioacetals using tetrabutylammonium dihydrogentrifluoride and N-halo compounds

Cyclic dithioacetals of aldehydes and ketones are converted into the corresponding difluoromethylene compounds with characteristic chemoselectivity by means of tetrabutyl-ammonium dihydrogen trifluoride and N-halo amides or imides (N-bromosuccinimide, N-iodosuccinimide and l,3-dibromo-5,5-dimethylhydantoin) in good to excellent yield. The substrates which have an acid-sensitive functionality or other easily fluorinated functionalities give the desired products without any damage to that functionality.