Synthesis of some new aminothiophene, pyridazine, pyrimidine and thienopyrimidine derivatives with expected biological activityAuthor(s): Ismail M.M.Othman, Hamdi M.D.Nasr
Treatment of 1 with active methylene reagents 2a, b and elemental sulfur furnished aminothiophene derivatives 3a, b. diazotization of 3a with active methylene compounds, namely malononitrile (5a) and acetylacetone (5b) afforded the corresponding hydrazono derivatives 6a, b. pyridazine derivatives 9a, b, 10 and 12a, b were obtained by reaction of 6a with ethylcyanoacetae, ethylacetoacetate, malononitrile and arylidinemalononitrile 11a, b, respectively. Furthermore, the reaction of 6b with urea and/or thiourea afforded the pyrimidine derivatives 14a, b.Also, the interaction of 3a with phenyl isothiocyanate, thiourea and formamide afforded the corresponding thienopyrimidine derivatives 16, 17 and 18 respectively. Schiff base 19 was obtained fromthe reaction of 3a with benzaldehyde. Condensation of 3a with DMF-DMA afforded the derivative 20. Compound 20 cyclized with hydrazine hydrate to give 23.Also, when compound 3b reacted with triethylorthoformate afforded the intermediate 21, which cyclized into the thienopyrimidine derivative 25. The reaction of 3b with phenyl isothiocyanate in boiling ethanol furnished the thiourea derivative 26. Treatment of 26 with hydrazine hydrate produced thienopyrimidine derivative 27.