Bis(2-methoxyethyl)aminosulfur trifluoride: A new broad-spectrum deoxofluorinating agent with enhanced thermal stability

Bis(2-methoxyethyl)aminosulfur trifluoride, (CH3OCH2CH2)(2)NSF3 (Deoxo-Fluo r reagent), is a new deoxofluorinating agent that is much more thermally st able than DAST (C2H5)(2)NSF3 and its congeners. It is effective for the con version of alcohols to alkyl fluorides, aldehydes/ketones to the correspond ing gem-difluorides, and carboxylic acids to the trifluoromethyl derivative s with, in some cases, superior performance compared to DAST. The enhanced stability is rationalized on the basis of conformational rigidity imposed b y a coordination of the alkoxy groups with the electron-deficient sulfur at om of the trifluoride.