Hydrochloric Acid → 1-Benzyl-4-methylpiperidin-3-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of the product from Method B (72.45 grams/0.387 mol) dissolved in 240 mL of THF was added 21.4 grams of NaBH4 and the mixture cooled to 0° C. A solution of borontrifluoride etherate (109.4 mL dissolved in 200 mL of THF) was then added dropwise over 1.5 hours. Once added, the reaction mixture was brought to room temperature and stirred for 2 hours. The reaction was again cooled to 0° C. and 29.3 mL of water were added dropwise over 15 minutes followed by dropwise addition of 2N sodium hydroxide (97.5 mL) over 20 minutes. The resulting mixture stirred at 0° C. for 40 minutes and was then brought to room temperature. Hydrogen peroxide (30%) (97.5 mL) was added dropwise at a rate so as not to exceed 50° C. in the reaction mixture (approximately 30 minutes). When the addition was complete, the reaction mixture stirred for 10 minutes, then was cooled to 0° C. Concentrated hydrochloric acid (97.5 mL) was added over 5 minutes, the reaction mixture was reduced to one third its volume in vacuo, and the pH adjusted to 9-10 with 6N sodium hydroxide (aq). The resulting mixture was extracted three times with ether, the combined ether layers dried over MgSO4 and evaporated to dryness in vacuo affording 65.32 grams (79%) of the title compound as yellow oil. LRMS: 206.1 (M+1).

Provenance & Evidence