Synthesis of Some Novel Polyaza Fused Heterocyclic Compounds

摘要

2-(1-Aryl-ethylidene)-malononitriles 1a-d undergo self dimerization in ethanol catalyzed by sodium ethoxide to afford 2-[4,6-diaryl-3-cyano-6-methyl-5,6-dihydropyridin-2(1H)-ylidene]-malononitrile derivatives 3a-d, respectively. The structure of the dimer was elucidated by X-ray crystallography and a plausible mechanism for its formation is depicted. Compound 3a couples with arene diazonium salts 4a-d to afford the hydrazo derivatives 5a-d; and reacts with hydrazine hydrate and phenylhydrazine 6a,b to afford the pyrazolo[3,4-h][1,6]naphthyridine derivatives7a,b; and with urea and thiourea 8a,b to afford the pyrimido[4,5-h][1,6]naphthyridine derivatives 9a,b, respectively.