Transformations of substituted cyanoiminooctahydroquinazolines under oxidation conditions

Substituted quinazolines of various degrees of saturation and functionalization possess a wide spectrum of biological activity, in particular, anticancer activity, which predetermines the importance of obtaining new representatives of this type of compounds and studying their practically useful properties. Methods for the preparation of 2-cyanoiminoquinazolines are poorly described in the literature, while their properties and oxidation reactions have not been studied at all. We have analyzed the stability of tautomeric forms of 2-cyanoiminoquinazolines, determined the activation energy of their formation using quantum-chemical calculations, studied their transformation under the action of strong oxidants (CrO3/AcOH, NaNO2/AcOH). Selective aromatization of the azoheterocycle and hydrolysis of the -CN-group to form 2-aminocarbamoylquinazoline occurred during oxidation. An increase in temperature from 120 to 160° C (using CrO3) resulted in the formation of 2-nitrosoquinazoline. The structure of our new obtained substances was established by spectral methods (IR, 1H, 13C NMR, HSQC, NOESY), a scheme of their formation has been proposed.