Hydrochloric Acid → 8,9-Dimethoxy-1,2,3,11b-tetrahydrochromeno[4,3,2-de]isoquinoline

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Reaction Steps

Platinum (IV) oxide (200 mg) was added to a solution containing 50 ml of acetic acid and isoquinoline 6 (1 g; 3.5 mmol). After adding 2.8 ml of concentrated HCl, the mixture was shaken on a Parr hydrogenator at 60 psi for 24 hours. The green solution was filtered through Celite to remove the catalyst and the majority of the acetic acid was removed by rotary evaporation. The remaining acid was neutralized using a saturated sodium bicarbonate solution, extracted with diethyl ether (3×250 ml), dried (Na2SO4), and concentrated. The resulting oil (0.997 g; 99%) was used without further purification: 1H NMR: (300 MHz, CDCl3): 7.10 (t, 1H, J=7.5 Hz); 7.00 (d, 1H, J=8.4 Hz); 6.78 (m, 2H); 6.60 (d, 1H, J=9 Hz); 4.10 (s, 2H); 3.84 (m, 8H); 2.93 (t, 1H, J=12.9 Hz).

Provenance & Evidence