Add a solution of 1,18-bis[[(phenyl)methyl]carbonyl]-5,14-bis-[(phenyl)methyl]-1,5,14,18-tetraazaoctadecane (3 g) in tetrahydrofuran (150 mL) dropwise to a suspension of lithium aluminum hydride (0.5 g) in tetrahydrofuran (500 mL). Stir the reaction for 48 hours at room temperature. Decompose the excess reducing agent by dropwise addition of water (1 mL), 15% sodium hydroxide (1 mL) and water (3 mL). Filter the mixture and concentrate the filtrate under vacuum. Dissolve the residue in ethanol (100 mL) and add anhydrous hydrogen chloride gas to provide the tetrahydrochloride salt of 1,18-bis[(2-phenyl)ethyl]-5,14-bis-[(phenyl)methyl]-1,5,14,18-tetraazaoctadecane. Scheme D, step C: Hydrogenate this product in ethanol (150 mL) in the presence of Pearlman's catalyst (0.3 g) at 43 psig on a Parr hydrogenation apparatus for 24 hours. Filter the reaction and concentrate the filtrate under vacuum. Crystallize the residue from 2-propanol to provide the title compound as a hemihydrate, mp 322-324° C. (dec.).
