Synthesis of Some New [1,8]Naphthyridine, Pyrido[2,3-d]-Pyrimidine, and Other Annulated Pyridine Derivatives

2-Aminopyridine-3-carbonitrile derivative 1 reacted with each of malononitrile, ethyl cyanacetate, benzylidenemalononitrile, diethyl malonate, and ethyl acetoacetate to give the corresponding [1,8]naphthyridine derivatives 3, 5, 8, 11, and 14, respectively. Further annulations of 3, 5, and 8 gave the corresponding pyrido[2,3-b][1,8]naphthyridine-3-carbonitrile derivative 17, pyrido[2,3-h][1,6]naphthyridine-3-carbonitrile derivatives 18 and 19, respectively. The reaction of 1 with formic acid, formamide, acetic anhydride, urea or thiourea, and 4-isothiocyanatobenzenesulfonamide gave the pyridopyrimidine derivatives 20a,b, 21, 22a,b, and 26, respectively. Treatment of compound 1 with sulfuric acid afforded the amide derivative 27. Compound 27 reacted with 4-chlorobenzaldehyde and 1H-indene-1,3(2H)-dione to give the pyridopyrimidine derivative 28 and spiro derivative 30, respectively. In addition, compound 1 reacted with halo compounds afforded the pyrrolopyridine derivatives 32 and 34. Finally, treatment of 1 with hydrazine hydrate gave the pyrazolopyridine derivative 35. The structures of the newly synthesized compounds were established by elemental and spectral data.