Electrophilic Sulfenylation/Cyclization of N‐Aryl and N‐Benzyl Propynamides: Synthesis of Sulfenyl Quinolinones and 3H‐Benzo[c]azepin‐3‐ones

Quinolinones and benzo[c]azepinones are important cores in biologically active molecules. We report the cyclization of N‐substituted propynamides, initiated by readily available electrophilic sulfenylating agent, enabling the synthesis of quinolinones and benzo[c]azepinones in exceedingly simple conditions. The approach shows excellent generality to the substrates and tolerability of functional groups. The anti‐inflammatory effect of the newly synthesized 3‐sulfenyl quinolinone and the 4‐sulfenyl benzo[c]azepinone products are tested, and two compounds are confirmed to have inhibitive effect on TNF‐α expression. A sulfenylation/cyclizationreaction of N‐substituted propynamides has been developed with dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTSM) as the initiator, providing the modular synthesis of 3‐sulfenyl quinolinones and 4‐sulfenyl benzo[c]azepinones.