Trifluoromethanesulfonyloxy group

Nucleophilic substitution at the unreactive site of an a-sulfonyl C-atom has been achieved by employing the excellent leaving ability of the trifluoromethanesulfonyloxy groups . Ammonium groups in N-heterocyclics can be replaced by a variety of nucleophiles . 

Synthesis of a-Imidostyrenes. a-Imidostyrenes, useful precursors to vinylamines can be synthesized by introducing an imido group to the a-position of styrenes with the diphenyl sulfoxide-Tf2 O reagent combination. Styrenes with a hydrogen atom at the a-position react with diphenyl(trifluoromethanesulfonyloxy)sulf-onuim triflate to form diphenylstyrylsuifonium triflates which, in turn are converted into the corresponding a-imidostyrenes on treatment with sodium or potassium salts of cyclic imides (eq 9). 

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