Trifluoroacetic acid → [1-Acetyl-3-(4-methylbenzyl)piperidin-3-yl]methanol

Participants

Reaction Steps

Trifluoroacetic acid (12.5 ml) was added to a solution of the product from STEP 3 (0.48 g, 1.4 mmol) in 12.5 ml dichloromethane at 0° C. The reaction was allowed to warm to room temperature. After 2 h, the reaction was concentrated, and dried in vacuo. The residue was dissolved in 20 ml dichloromethane, then triethylamine (1.82 g, 18.0 mmol) and dimethylaminopyridine (30 mg) were added. Acetic anhydride (1.13 ml, 12.0 mmol) was added to the above mixture at 0° C. The reaction mixture was allowed to warm to room temperature. After 18 h, the reaction was diluted with 150 ml dichloromethane, washed with 10 ml H2O, 5 ml brine, dried with MgSO4, and concentrated. The residue was dissolved in 25 ml methanol. An aqueous saturated K2CO3 solution (15 ml) was added at 0° C. The reaction was allowed to warm to room temperature. After 1.5 h, glacial acetic acid was added to adjust PH value to 6.5. The reaction was concentrated and product was extracted with ethyl acetate. The organic extracts were washed with brine, dried with MgSO4, and concentrated. The residue was purified by chromatography (SiO2, CH2Cl2/MeOH/NH4OH=90/10/0.2) to afford 0.14 g of an viscous oil. The 1H NMR spectrum of the product was consistent for the proposed structure.

Provenance & Evidence