Regioselective Access to Sultam Motifs through Cobalt-Catalyzed Annulation of Aryl Sulfonamides and Alkynes using an 8-Aminoquinoline Directing Group

The use of cobalt as catalyst in direct C-H activation protocols as a replacement for more expensive second row transition metals is currently attracting significant attention. Herein we disclose a facile cobalt-catalyzed C-H functionalization route towards sultam motifs through annulation of easily prepared aryl sulfonamides and alkynes using 8-aminoquinoline as a directing group. The reaction shows broad substrate scope with products obtained in a highly regioselective manner in good to excellent isolated yields. Mechanistic insights suggest the formation of a Co(III)-aryl key species via a rate-determining arene C-H activation during the annulation reaction.