Acid-Mediated Intramolecular Cyclizations of ( N -Aryl)-acetylenic Sulfonamides: Synthesis of Fused and Spirocyclic Sultams.

Herein, we report acid-mediated divergent annulations of ( N -aryl)-alkynyl sulfonamides. The substituent at the para position of the N -aryl group determines two diverse reaction paths, leading to the selective assembly of benzo-fused sultams and spirocyclic sultams. This strategy provides a series of benzo/spiro-sultams with wide functional group compatibility and good to excellent yields under mild reaction conditions. Additionally, scale-up reaction and further transformations of the products were also carried out to demonstrate the utility of the protocol.