2-Alkyl-1,3-dithiane derivatives, easily made from alkyl bromides and the parent 1,3-dithiane, were reacted with BrF 3 to form the corresponding 1,1-difluoromethyl alkanes (RCHF 2 ) in 60−75% yield. The reaction proceeds well with primary alkyl halides. The limiting step for secondary alkyl halides is the relatively low yield of the dithiane preparation. The two sulfur atoms of the dithiane are essential for the reaction.

alpha-Fluorocarboxylic esters and acids were synthesized in good yields. The corresponding esters and acids were converted to their ketene acetals, and these enol derivatives reacted with AcOF made directly from fluorine. This route circumvents the problems associated with nucleophilic fluorinations such as various eliminations and rearrangements. alpha- and beta-branched carboxylic acid derivatives that cannot be directly fluorinated gave by this electrophilic fluorination the corresponding alpha-fluoro derivatives in good yield. Both the fluorination reaction and the preparation of AcOF are fast and suitable for [18]F incorporation into acids and esters needed for working with PET. alpha-Fluoroibuprofen (20) and methyl 2-fluoro-3,3,3-triphenylpropionate (32) are two examples of this general reaction.