Abstract
magnified image Four‐component one pot cyclocondensation of aromatic aldehydes 1, ethyl cyanoacetate 2, barbituric acid 3 and ammonium acetate in methanol gave substituted and functionalised pyrido[2,3‐d]pyrimidine derivatives 4 and 4′ after initial Knoevenagel, subsequent Micheal and final heterocyclization reactions. Compounds 4 on reaction with different active methylene compounds resulted in the formation of again functionalized and diversly substituted pyrimidonaphthyridines 5‐7, 9 and benzo[b] pyrimidonaphthyridines 8. The various compounds of systems 7 and 8 on further condensation with the reactive and mostly the bifunctional moieties like urea/thiourea, and 2‐aminopyridine generated the novel and differently fused dipyrimidonaphthyridines 10/11 and pyrimidonaphthyridinoquinazolines 13/14, and pyridopyrimido‐ pyrimido[1,8]naphthyridines 15 and pyrimidonaphthyridino‐ pyridoquinazolines 16, respectively, hitherto unknown in literature. Compounds 7 on condensation with o‐phenylenediamine produced novel pyrimidonaphthyridinobenzodiazepines 12. Other novel systems like pyrido[2,3‐d;6,5‐d′]dipyrimidines 17, dipyrimido[4,5‐b:5′,4′‐g][1,8]naphthyridines 18, 1,3,4,6,7,8,9,11‐octazabenzo[de]naphthacenes 19, dipyrimido[4,5‐b:5′,4′‐g][1,8]naphthyridines 20, pyrimido[5′,4′:6,7][1,8]naphthyridino[4,3‐b][1,5]benzodiazepines 21, dipyrimido[4,5‐b:4′,5′‐f][1,8]naphthyridines 22 and dipyrimido [4,5‐b:5′,4′‐g][1,8] naphthyridines 23 have also been generated in this study. J. Heterocyclic Chem., (2010).