Synthesis of Heterocycles via 2-Thioxo-1,2-dihydropyridine-3-carbonitrile Derivative

Abstract

The present study aimed to investigate the synthetic potentiality and chemical reactivity of 2-thioxo-1,2-dihydropyridine-3-carbonitrile derivative 1. This goal performed via its reaction with each of 1-chloroacetone and iodomethane to afford the corresponding 2-alkylthio derivatives 3 and 9, respectively. Compound 3 underwent intramolecular cyclization to afford the corresponding thieno[2,3-b]pyridine derivative 4 which in turn, reacted with dimethylformamide/dimethylacetal followed by hydrazine hydrate and nitrous acid to afford the corresponding pyridothienopyrimidine and pyridothienopyridazine derivatives 6 and 8, respectively. On the other hand, Compound 9 reacted with hydrazine hydrate to give 3-aminopyrazolo[3,4-b]pyridine derivative 10, which diazotized with nitrous acid to give the corresponding diazonium salt 11. Compound 11 coupled with several active –CH₂-containing reagents to synthesize the corresponding pyridopyrazolo-triazines 15, 24, 29, and 31. The formulas of all newly synthesized heterocyclic compounds were elucidated by considering the data of IR, ¹H NMR, Mass spectral data, as well as data from elemental analyses.

Keywords:

• 2-Thioxohydropyridine-3-carbonitrile
• pyridopyrazolotriazine
• thieno[2,3-b]pyridine
• thienopyridopyridazine
• thienopyridopyrimidine