SYNTHESIS OF SOME BENZOFURANYL THIENO[2,3-D] PYRIMIDINE DERIVATIVES WITH BIOLOGICAL INTEREST

Interaction of visnaginone or khellinone (1a,b) with cyanoacetamide, ethyl cyanoacetate or molanonitrile and elemental sulfur in presence of triethylamine afforded thiophene enamino derivatives (2a-d) respectively according to Gewald method. Acetylation of 2a with acetic anhydride gave 3. Condensation of 2b with p-chlorobenzaldehyde yielded 4. Compound 6 was afforded from reaction of enamino carboxamide (2b) with thiourea.. Compound 2b reacted with benzoyl chloride to give thienopyrimidine (8). N-phenyl thienopyrimidine (11) and N-amino thienopyrimidine (13) were prepared from reaction of 2c with phenyl isothiocyanate and hydrazinolysis of 12 with hydrazine hydrate.
The structures of these compounds were confirmed by infrared, mass and 1H-NMR spectra. The biological activity of some compounds were discussed and found to be active.