Abstract
A simple one-pot method is reported for the synthesis of several novel series of chromeno[4', 3':4,5] pyrido[2,3-d][1,2,4] triazolo[ 4,3-a] pyrimidine-6,14-diones, chromeno[4', 3': 4,5] pyrido[ 2,3-d] thiazolo[3,2-a] pyrimidine-6,14-diones, and chromeno[ 4 '', 3 '': 4', 5'] pyrido[2', 3': 4,5] pyrimido[2,1-b][1,3]thiazine-6,15-dione by a multicomponent reaction of salicylaldehyde, ethyl acetoacetate, and the appropriate fused heterocyclic amines in refluxing glacial acetic acid. The structures of the newly synthesized compounds were established by spectroscopy and elemental analyses. The mechanism of the single-step reaction was elucidated.