The condensation of 5-amino 2 methyl 4,6-dichloropyrimidine (I) with 1-acetyl-2-imidazolin-2-one (II) by means of POCl3 at 50 C gives 4,6-dichloro-2-methyl-5-(1-acetyl-2-imidazolin-2-ylamino)pyrimidine (III), which is then methoxylated and desacetylated by treatment with sodium methoxide in refluxing methanol.