Arylsulfur trifluorides: Improved method of synthesis and use as in situ deoxofluorination reagents

Building on recent results of Umemoto and Winter, an improved method of synthesis of arylsulfur trifluorides, including the excellent, new deoxofluorination reagent Fluolead, is hereby reported. The method utilizes Br2 and KF as oxidizing and fluorinating reagents for efficient, high yield conversion of aryl disulfides and mercaptans to arylsulfur trifluorides. It has also been shown that both Fluolead and mesitylsulfur trifluoride may be generated in acetonitrile and used as in situ deoxofluorination reagents for conversion of either aldehydes or ketones to their respective gem-difluoro compounds. An analysis of the probable mechanism of action, including computational efforts, allows postulation of a rationale for the highly variable reactivities of different arylsulfur trifluorides as deoxofluorination reagents.