Base-promoted synthesis of dihydrochromeno[4,3-d]pyrrolo[3,4-b]pyridines from 4-chloro-3-substituted coumarins and α-aminomaleimides

Abstract

This paper describes the base-mediated cascade reactions of 4-chloro-3-substituted coumarins with α-aminomaleimides, allowing the efficient synthesis of dihydrochromeno[4,3-d]pyrrolo[3,4-b]pyridines with interesting chemoselectivity. These transformations include the domino-style formation of C–C/C–N bonds through a base-mediated nucleophilic substitution, Michael addition, N-cyclization, and elimination. The presented synthetic strategy has several advantages: it is simple, uses readily available starting materials and an environmentally friendly solvent, has a highly chemoselective route, and allows the purification of products via washing with EtOH (96%), a technique called GAP (Group-Assisted-Purification) chemistry.