Synthesis of Heteroannulated Chromeno[2,3-b]Pyridines: DBU Catalyzed Reactions of 2-Amino-6-methylchromone-3-Carboxaldehyde with Some Heterocyclic Enols and Enamines

Abstract

New series of heteroannulated chromeno[2,3-b]pyridines were easily and efficiently synthesized from DBU-catalyzed condensation of 2-amino-6-methylchromone-3-carboxaldehyde with a variety of heterocyclic enols and enamines, namely, 4-hydroxycoumarin, 4-hydroxy-1-methylquinolin-2(1H)-one, 2-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one, 4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione, 4(6)-aminouracil and 5-amino-3-methyl-1H-pyrazole. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.