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

Regioselective reactions of morpholine‐1‐carbothioic acid (2‐phenyl‐3 H ‐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‐3 H ‐quinazolin‐4‐ylidene) thioureas and l‐substituted‐3‐(2‐phenyl‐quinazolin‐4‐yl) thioureas via transami‐nation reaction. The reaction of ( 1 ) with amines in the presence of H 2 O 2 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, 1 H nmr, 13 C nmr, mass spectroscopy and x‐ray identified the isolated products.