Synthesis of Some New [1,8]Naphthyridine, Pyrido[2,3‐<i>d</i>]‐Pyrimidine, and Other Annulated Pyridine Derivatives

Abstract

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 1 H ‐indene‐1,3(2 H )‐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.