Synthesis and characterization of new chromeno[2,3‐b]pyridines via the Friedländer reactions of 8‐allyl‐2‐amino‐4‐oxo‐4H‐chromene‐3‐ carboxaldehyde

Abstract

New series of chromeno[2,3‐b]pyridines, 2‐8, have been obtained from 1,8‐diazabicyclo [5.4.0]undec‐7‐ene catalyzed Friedländer reaction of 8‐allyl‐2‐aminochromone‐3‐ carboxaldehyde (1) with some carbonyl compounds containing a reactive α‐methyl or methylene group namely 2‐acetylthiophene, 3‐acetylpyridine, 4‐chloroacetophenone, 4,6‐ diacetylresorcinol, acetylacetone, dibenzoyl methane and acetoacetanilide. Heteroannulated chromones, 13‐16, were prepared from Friedländer reaction of 1 with some cyclic α‐ methylene ketones namely 2‐phenyliminothiazolidin‐4‐one, pyrazoline‐3,5‐dione, 5,5‐ dimethylcyclohexane‐1,3‐dione and thiobarbituric acid. Structures of the newly synthesized compounds have been established from elemental analysis and spectroscopic data.