“…TFA (trifluoroacetic acid), room temp. }, which was originally developed by Achiwa and coworkers, and has been widely used by us and others in recent years, could be used for a reaction with the parent commercially available vinyl sulfonyl fluoride 1a (Scheme , R 1 = R 2 = H). We found that under these typical conditions, the target adduct 3a was obtained in 75 % yield (Table ).…”