Syntheses of 2-amino-4,6-dichloro-5-nitropyrimidine and 2-amino-4,5,6-trichloropyrimidine: an unusual aromatic substitution

2-Amino-4,6-dichloro-5-nitropyrimidine is an intermediate required for the preparation of nitropyrimidines as inactivators of the DNA repairing protein MGMT. When attempting its synthesis, 2-amino-4,5,6-trichloropyrimidine is obtained instead, via unusual aromatic substitution of the nitro group in 2-amino-4-hydroxy-5-nitropyrimidin-6-one by chloride. The synthesis, the reactivity of 4,5,6-trichloropyrimidine and the efficient preparation of 2-amino-4,6-dichloro-5-nitropyrimidine are presented.