Hydrochloric Acid → 1-(2-Aminoethyl)-4,4-diphenylpiperidine

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Reaction Steps

To a stirred solution of (4,4-diphenylpiperidin-1-yl)acetonitrile (3.90 g, 14.1 mmol, 1.0 equiv) in anhydrous THF (10 mL) under argon was added a solution of BH3 in THF (1.0 M, 50 mL, 50 mmol, 3.5 equiv) at room temperature. The mixture was refluxed for 4.5 hours and then cooled to room temperature and concentrated to a volume of about 30 mL. Aqueous HCl (6 N, 50 mL) was added cautiously and stirring was continued for 2 hours at 50° C. The mixture was cooled to room temperature, basified to pH 10 by addition of 6 N aq. NaOH, and extracted with CH2Cl2 (3×100 mL). The combined organic solutions were dried over MgSO4 and concentrated. To a solution of the residue in CH2Cl2 (30 mL) was added HCl in ether (1.0 M, 16 mL, 1.1 equiv). After removal of the solvents, the residue was dissolved in CH2Cl2 (10 mL) and this solution was added dropwise into ether (100 mL) with swirling. The resulting solid was filtered and washed with ether (3×50 mL). This solid was taken up in water (20 mL), which was basified to pH 10 by addition of 1 M aqueous NaOH, and extracted with CH2Cl2 (3×50 mL). The combined organic solutions were dried over MgSO4 and concentrated to give 3.70 g (94%) of white solid, which was characterized spectroscopically.

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