Trifluoroacetic acid → 1-(3-Amino-2-hydroxy-4-phenyl-butyl)-piperidine-3-carboxylic acid [4-phenyl-1-(3-phenyl-propyl)-butyl]-amide

(1-Benzyl-2-hydroxy-3-{3-[4-phenyl-1-(3-phenyl-propyl)-butylcarbamoyl]-piperidine-1-yl}-propyl)-carbamic acid tert-butyl ester (19) (194.4 mg; 0.3 mmol) is dissolved in methylene chloride (5 mL) at ambient temperature. Trifluoroacetic acid (5 mL) is added in a slow stream, and the solution is stirred for 90 minutes at ambient temperature. The solution is concentrated in vacuo at 40° C. The residue is slurried in a mixture of methylene chloride (10 mL) and water (100 mL), then potassium carbonate is added until the slurry is alkaline. The slurry is diluted with water (50 mL) then extracted with methylene chloride (3×50 mL). The organic extracts are dried over MgSO4, filtered, and concentrated in vacuo affording the desired product (150 mg) as an oil.