[CH:1]([C:3]1[CH:16]=[CH:15][C:6]([C:7]([N:9]2[CH2:14][CH2:13][CH2:12][CH2:11][CH2:10]2)=[O:8])=[CH:5][CH:4]=1)=[O:2].[BH4-].[Na+]>C(O)C>[OH:2][CH2:1][C:3]1[CH:4]=[CH:5][C:6]([C:7]([N:9]2[CH2:14][CH2:13][CH2:12][CH2:11][CH2:10]2)=[O:8])=[CH:15][CH:16]=1The aldehyde (28.6 mmol) thus formed was dissolved in 40 mL of absolute ethanol, and 540 mg NaBH4 was added over 2 hours. When thin-layer chromatography revealed no remaining aldehyde, the reaction was quenched with 2.5 mL acetic acid. The ethanol was removed on a rotary evaporator and the residue was taken up in 30 mL water. The product alcohol was extracted with two 25-mL volumes of CH2Cl2 plus 25 mL ether. The organic extracts were combined and dried over Na2SO4. Removal of the solvents on a rotary evaporator yielded 4.08 g of 1-(4'-hydroxymethylbenzoyl)piperidine, which was collected by filtration and washed with petroleum ether. The product (Compound IV, 1-(4'-hydroxymethylbenzoyl)piperidine) had a melting point of 119.6°-122.7° C. 1H NMR showed the methylene protons at 4.715 (2H, d, J=5.5 Hz) ppm.
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