The interaction of methyl anthranilate with N-(4,6-dimethylpyrimidin-2-yl)cyanamide, according to quantum-chemical calculations, X-ray diffraction, and spectral characteristics of a product obtained, leads exclusively to 2-[(4,6-dimethylpyrimidin-2-yl)amino]quinazolin-4(3H)-one and not to its isomer 2-amino-3-(4,6-dimethylpyrimidin-2-yl)quinazolin-4(3H)-one.