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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(1 H)-one, 2-hydroxy-4 H-pyrido[1,2- a]pyrimidin-4-one, 4-hydroxy-2 H-pyrano[3,2- c]quinoline-2,5(6 H)-dione, 4(6)-aminouracil and 5-amino-3-methyl-1 H-pyrazole. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data. [ABSTRACT FROM AUTHOR]

Six new title pyridines are prepared by cyclocondensation of chromonealdehyde (I) with a variety of heterocyclic enols and enamines. [ABSTRACT FROM AUTHOR]