Base‐Promoted Structural Rearrangement of Ynamide and Simultaneous N‐Desulfonylation

Abstract Herein, we describe a base‐promoted regioselective and chemoselective cascade cyclization, ynamide N−C sp bond cleavage, selective intramolecular 1,3‐migration, and simultaneous N ‐desulfonylation strategy for the synthesis of 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole derivatives. We observed multiple bond breaking (−N−Ts, and C sp 2 −Ts, C sp 2 −I/C sp 2 −SePh) from ( E )‐3‐(1‐iodo‐2‐phenyl‐2‐tosylvinyl)‐2‐phenyl‐1‐tosyl‐indole/( E )‐2‐phenyl‐3‐(2‐phenyl‐1‐(phenylselanyl)‐2‐tosylvinyl)‐1‐tosyl‐indole derivatives to prepare 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole in 15–60 min using our standard reaction conditions. A gram‐scale experiment as well as postsynthetic transformations of the synthesized 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole were performed to exhibit the advantages of this synthetic methodology.