To a solution of 1-cyclohexylcyclohexane-1-carbonyl chloride (2.1 g) in acetonitrile (30 ml), 5-hydroxy-2-nitroiminohexahydropirimidine (1.28 g) was added portionwise. The mixture was stirred at room temperature overnight, then DMF (10 ml) was added and the mixture was heated to 50° C. for 24 hours. The reaction was quenched with water. The precipitate was collected, dried and triturated with diethyl ether to afford 0.93 g of 2-nitroiminohexahydropyrimidin-5-yl 1-cyclohexylcyclohexane-1-carboxylate.
