Replacing the carbonyl's oxygen with the difluoromethyl group

Aldehydes or ketones were reacted with 2-(trimethylsilyl)-1,3-dithiane (1) and the products reduced to the corresponding dithianes using tetrafluoroboric acid and sodium borohydride. These sulfur containing compounds were reacted with bromine trifluoride under mild conditions (1-2 min, 0 °C) with a net result of replacing the carbonyls' oxygen with the desired difluoromethyl moiety.