Reactivity study on morpholine-1-carbothioic acid (2-phenyl-3H-quinazolin-4-ylidene) amide

Regioselective reactions of morpholine-1-carbothioic acid (2-phenyl-3H-quinazolin-4-ylidene) amide (1) with electrophiles and nucleophiles were studied. The compound (1) reacts with alkyl halides in basic medium to afford S-substituted isothiourea derivatives, with amines to give 1,1-disubstituted-3-(2-phenyl-3H-quinazolin-4-ylidene) thioureas and 1-substituted-3-(2-phenyl-quinazolin-4-yl) thioureas via transamination reaction. The reaction of (1) with amines in the presence of H2O2 provided N-4-disubstituted-N-4-(2-phenylquinazolin-4-yl)morpholin-4-carboximidamide via oxidative desulfurization. Estimation of reactivity sites on (1) was supported using the ab initio (HF/6-31G**) quantum chemistry calculations. The ir, H-1 nmr, C-13 nmr, mass spectroscopy and x-ray identified the isolated products.