Hydrochloric Acid → Tapentadol Hydrochloride

Participants

Reaction Steps

The product of Example 6 (2.5 g, 8 mmol) was dissolved in methanol, 5% Pd—C (250 mg) was added, and it was purged with hydrogen for three times, then the reaction was carried out with stirring at room temperature for 1 hr. The reaction solution was filtered to remove Pd—C, the residue was washed with methanol for 3 times, then the organic phases are combined and concentrated to 2 ml. After that, the concentrated hydrochloric acid (670 ml, 8 mmol) was added dropwise, then the resulted solution was concentrated and recrystallized with isopropanol and ethyl acetate to give the target 1.9 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