A solution of 0.590 g (2.02 mmol) of 1-benzyl-4-(3-phenylpropyl)-1,2,3,6-tetrahydropyridine and 4.4 mL of a 1M solution of BH3.THF in THF in 5 mL of THF was heated under reflux for 1 h. The mixture was cooled to rt, and 5 mL 1N NaOH and 5 mL 30% H2O2 were added and stirring was continued for 0.5 h. The mixture was partitioned between 75 mL of ether and 25 mL of H2O. The combined organic fractions were washed with sat'd NaCl solution, dried over MgSO4, filtered and the filtrate was concentrated. The residue and 2 mL of ethanolamine were combined in 2 mL of methanol and heated under reflux for 1 h. The mixture was cooled to rt and partititioned between 100 mL of ether and 50 mL of sat'd NaCl solution. The combined organic fractions were washed with sat'd NaCl solution, dried over MgSO4, filtered and the filtrate was concentrated. The residue was purified by chromatography (silica, hexanes:ethyl acetate, 2:1) to give 1-benzyl (trans)-3-hydroxy-4-(3-phenylpropyl)piperidine. Removal of the benzyl protecting group was achieved under standard conditions.
