A solution of sodium cyanoborohydride (0.13 g) in methanol (4 ml) is added to a mixture of 1-[1,1-dimethylethoxycarbonyl]-4-[5-amino-6-pyrimidinyl]piperazine (PREPARATION 10, 0.44 g), acetone (3 ml), and glacial acetic acid (0.4 ml) in methanol (7 ml) at 0°. The mixture is stirred at 20°-25° for 72h. The reaction is diluted with an aqueous sodium hydroxide solution (10%) and dichloromethane. The phases are separated and the organic phase is washed with water and the concentrated to a colorless liquid which is flash chromatographed on silica gel eluting with methanol/chloroform (1/99). The appropriate fractions are pooled and concentrated to give the title compound, NMR (CDCl3) 1.26, 1.49, 3.2, 3.44, 3.5-3.62, 7.89 and 8.33 δ.
