The cyclization of ethyl 2-(1-adamantyl)acetoacetate (I) with guanidine (II) gives 2-amino-4-hydroxy-5-(1-adamantyl)-6-methylpyrimidine (III), which by treatment with PCl5 in refluxing POCl3 is converted into 2-amino-4-chloro-5-(1-adamantyl)-6-methylpyrimidine (IV). Finally, this compound is treated with NH3 in ethanol, and with ethanesulfonic acid.