Convenient general preparation of oxygenated monofluoro- and gem-difluoro-5a-androstanes using diethylaminosulphur trifluoride

Hydroxy-ketones in the 5α-androstane series are converted into fluoro-ketones by diethylaminosulphur trifluoride under mild conditions; acetoxy-ketones give acetoxydifluorides under more vigorous conditions.