Hydrochloric Acid → Tapentadol Hydrochloride

Participants

Reaction Steps

Lithium aluminum tetrahydride (730 mg, 20 mmol) was suspended in tetrahydrofuran (10 ml), and it was cooled in an ice-water bath, then the solution of product of Example 26 (2 g, 8.5 mmol) in tetrahydrofuran (10 ml) was added dropwise, the reaction was carried out for 2 hours and then quenched by adding 10% NaOH aqueous solution. The reaction solution was then extracted with ethyl acetate for three times, and the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated to 2 mL, then the concentrated hydrochloric acid (710 μl, 8.5 mmol) was added dropwise therein, and the resulted solution was concentrated and recrystallized with isopropanol-ethyl acetate to obtain the target 1.97 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