Like pyridine 1-oxide, 4-ethyl-6-methylpyrimidine 1-oxide reacts with phenyl isocyanate ; the products in the latter case are 2-anilino-4-ethoxy-6-methylpyrimidine and 1, 3-diphenyl-1-(4-ethoxy-6-methyl-2-pyrimidinyl) urea. In contrast to this reaction, phenyl isothiocyanate transformed the same N-oxide into 7-methyl-3-phenyl-2, 3-dihydrooxazolo [4, 5-d] pyrimidine-2-thione.
