A Reaction of Triazoles with Thioesters to Produce β‐Sulfanyl Enamides by Insertion of an Enamine Moiety into the Sulfur–Carbonyl Bond

N‐Sulfonyl‐1,2,3‐triazoles react with thioesters in the presence of a rhodium(II) catalyst to produce β‐sulfanyl enamides in a stereoselective manner. The reaction proceeds through generation of an α‐imino rhodium carbene complex, nucleophilic addition of the sulfur atom of a thioester onto the carbenoid carbon atom, and subsequent intramolecular migration of the acyl group from the sulfur atom to the imino nitrogen atom. The method is successfully applied to a ring‐expansion reaction of thiolactones, thus leading to the formation of sulfur‐containing lactams.