Lewis Acid Mediated Trifluoromethylthio Lactonization/Lactamization.

A highly selective Lewis acid mediated trifluoromethylthio lactonization/lactamization of olefins is described. The reaction was proposed to proceed via a thiiranium ion intermediate, which was further attacked by the carboxylic acid or amide to generate the corresponding trifluoromethylthiolated lactone/lactam.