1,5-Diphenylpentan-3-one → 1,5-Diphenylpentan-3-amine

To a solution of 1,5-Diphenylpentan-3-one (5.26 g, 22.1 mmol), ammonium acetate (8.52 g, 110.5 mmol) and sodium acetate (9.06 g, 110.5 mmol) in methanol (80 mL) was added a solution of sodium cyanoborohydride (1.67 g, 26.52 mmol) in methanol (20 mL) and the reaction heated to reflux. After stirring at reflux for 30 min, the reaction was cooled and concentrated to dryness. The residue was partioned between methylene chloride and 2N sodium hydroxide. The organic phase was separated, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. Chromatography of the residue on silica gel (elution with 2-5% methanol/methylene chloride) provided N-(1-phenethyl-3-phenyl-propyl)amine. To a solution of the above amine (2.1 g, 8.82 mmol) in ethanol (50 mL), was added 2-imidazole-carboxaldehyde (813 mg, 8.47 mmol) and the reaction heated to 50° C. After stirring for 2 hr, the resulting homogeneous solution was treated with sodium borohydride (400 mg, 10.58 mmol) and allowed to stir overnight. The reaction was concentrated to dryness and the residue was partioned between methylene chloride and 2N sodium hydroxide. The organic phase was separated, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. Chromatography of the residue on silica gel (elution with 5% methanol/methylene chloride) provided compound 22.