A new approach to 2-amino-6-(methoxycarbonyl)amino-4-(1,2,3,6-tetrahydro-1-pyridyl)pyrimidine 1-oxide ( 3) is described. Methyl [1-ethoxy-2-(ethoxycarbonyl)-ethylidene]carbamate ( 5) reacted with guanidine to the pyrimidinecarbamate 6, which was successively transformed into methyl 2-amino-6-( p-tolyslulfonyl)oxy-4-pyrimidinecarbamate ( 8). Oxidation of 8 led to the corresponding pyrimidine N-oxide 9, a useful starting material to 3.