Abstract The s-triazolo [4, 3-c] quinazolines were obtained from 4-hydrazinoquinazolines by condensation with ethyl orthoformate. 4-Hydrazinoquinazoline were prepared by hydrazinolysis of corresponding quinazoline-4-thiones which in turn were obtained by isomerization of amidinoyl isothiocyanates. The infrared and 1 H NMR spectra of the final products are interpreted.
