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

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.