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