A mixture of 6,6-difluoro-1,12-diphthalimido-4,9-di-p-toluenesulfonyl-4,9-diaza-dodecane (3.4 g, 4.22 mM), ethanol (8.5 mL) and 8.5 mL of a 1N solution of hydrazine hydrate in ethanol is stirred and heated (bath temperature: 90° C.) overnight. Evaporation and stripping twice with methanol yields a residue which is dissolved in a mixture of water (20 mL), methanol (20 mL), and concentrated HCl (40 mL), and heated (bath temperature: 90° C.) under reflux for 3 hours. The reaction mixture is cooled, filtered and evaporated, and the residue is dissolved in hot 1N HCl. The solution is filtered, the filtrate is evaporated, and the residue is stripped with isopropanol (twice) and ethanol (twice). The residue is dissolved in ethanol, ether is added, and upon evaporation of the solvent, there is obtained 1,12-diamino-6,6-difluoro-4,9-di-p-toluenesulfonyl-4,9-diaza-dodecane as a white crystalline foam: 2.7 g (quantitative yield).
