Palladium‐Catalyzed Denitrogenative Sonogashira Coupling of Benzothiatriazine Dioxides

A denitrogenative Sonogashira coupling of N ‐alkyl benzothiatriazine dioxides catalyzed by 1 mol% PdCl 2 (PPh 3 ) 2 or 1 mol% PdCl 2 (PPh 3 ) 2 /CuI for aryl or alkyl alkynes, respectively, has been developed for highly efficient synthesis of o ‐alkynylbenzenesulfonamides. The scope of this protocol has been demonstrated by >30 examples, with yields of up to 98%, showing a good compatibility with common functional groups. In addition, a one‐pot denitrogenative alkynylation/5‐ exo ‐ dig cyclization of N ‐alkyl benzothiatriazine dioxides with aryl alkynes is also described preliminarily under the palladium/copper bimetallic catalysis in the presence of tetrabutyl ammonium bromide (TBAB) additive.