gem-Difluorination of 2,2-diaryl-1,3-dithiolanes by Selectfluor and pyridinium polyhydrogen fluoride.

2,2-diaryl-1,3-dithiolanes, readily obtainable from diaryl ketones, were transformed into the corresponding gem-difluoro compounds using a novel reagent combination involving Selectfluor and pyridinium polyhydrogen fluoride (PPHF) under mild conditions in moderate to good yields.