Hydrochloric Acid → Tapentadol Hydrochloride

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Reaction Steps

The product of Example 16 (1.9 g, 8 mmol) was dissolved in dichloromethane, the mixture was cooled in an ice-water bath, and a solution of boron tribromide (1.9 ml, 20 mmol) in dichloromethane was slowly added dropwise, then it was gradually raised to room temperature to make it react for 15 hrs. After it was cooled in an ice-water bath, methanol was slowly added dropwise to quench the reaction, and the organic phase was washed with water and saturated brine, dried over anhydrous sodium sulfate, and concentrated to 2 mL, then the concentrated hydrochloric acid (670 Ml, 8 mmol) was added dropwise, and the mixture was concentrated and recrystallized with isopropanol and ethyl acetate to obtain the target 1.8 g, yield: 90%. [α]D=+24.3° (c=1.10, CH3OH). 1HNMR (300 MHz, CD3OD): δ 7.2 (1H, t, J=7.9, 15.6), 6.6-6.8 (3H, m), 2.8-2.9 (2H, m), 2.7-2.8 (6H, br s), 2.2-2.3 (1H, m), 2.1-2.2 (1H, m), 1.8-1.9 (1H, m), 1.5-1.6 (1H, m), 1.2 (3H, d, J=6.7), 0.8 (3H, t, J=7.4, 14.4). ESI-MS: 222.4 (M+H).

Provenance & Evidence