Mechanistic Insights into the Decarboxylative Electrophilic Trifluoromethylthiolation of β-Ketocarboxylic Acids

A metal-free protocol for the domino trifluoromethylthiolation/decarboxylation of β-ketocarboxylic acids is described. The catalytic reactions take place in acetonitrile in the presence of aqueous ammonium hydroxide and N-trifluoromethylthiosaccharin. The sequence of events and reaction mechanism were established experimentally and using density functional theory calculations. This synthetic method offers a convenient alternative to known routes for the synthesis of α-trifluoromethylthio-substituted ketones.