Engaging thieno[2,3‐b]indole‐2,3‐dione for the efficient synthesis of spiro[indoline‐3,4′‐thiopyrano[2,3‐b]indole] by reaction with N‐substituted isatilidenes

Abstract A simple and efficient method, proceeding through a new mechanistic pathway, for the synthesis of spiro[indoline‐3,4‐thiopyrano[2.3‐b]indole derivatives have been developed by exploiting the reaction of thieno[2,3‐b]indole‐2,3‐dione with N‐substituted isatilidenes. The compounds synthesized have been screened for antibacterial activity. The generality of the reaction and mechanistic rationale are presented.