To a mixture of tris(hydroxymethyl)nitromethane (118.9 g), sodium bicarbonate (40 g) and water (1000 ml), N-benzyl-N'-methylethylenediamine (123 g) is added, and the reaction mixture is heated at about 50° C. for 2 hours. After cooling, the solution is extracted with dichloromethane, and the organic layer is washed with saturated aqueous sodium chloride and dried over magnesium sulfate. The solvent is evaporated under reduced pressure to give 1-benzyl-6-hydroxymethyl-4-methyl-6-nitrohexahydro-1H-1,4-diazepine as an oil.
