Hydrochloric Acid → Racemic 4-benzofuran-2-yl-2,7-dimethyl-1,2,3,4-tetrahydroisoquinoline

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Racemic 4-benzofuran-2-yl-2,7-dimethyl-1,2,3,4-tetrahydroisoquinoline was prepared from 2-acetylbenzofuran and 3-tolylmethylamine as described in Example 26. This racemic compound (105 mg) was separated on semi-prep chiral HPLC (chiralcel OD-H, 1×25 cm, eluent: 3% ethanol in heptane, flow: 4 ml/minute, 500 μl injections, 5 mg/injections). The resulting free bases were dissolved in ethyl acetate and treated with a 2 M solution of HCl in diethyl ether (2 equiv) to give (+)-4-benzofuran-2-yl-2,7-dimethyl-1,2,3,4-tetrahydroisoquinoline, hydrochloride salt (39 mg, 100% AUC HPLC, 99.4% AUC chiral HPLC): 1H NMR (300 MHz, Acetone-d6) δ7.63-7.70 (m, 1H), 7.20-7.47 (m, 6H), 7.00-7.08 (m, 2H), 5.31-5.43 (m, 1H), 4.43-4.62 (m, 2H), 3.70-3.88 (m, 2H), 3.01 (s, 3H); EI MS m/z=277 [C19H19NO]+, [α]25D+20° (c 1.0, MeOH, free base) and (−)-4-benzofuran-2-yl-2,7-dimethyl-1,2,3,4-tetrahydroisoquinoline, hydrochloride salt (40 mg, 100% AUC HPLC, 100% chiral HPLC): 1H NMR (300 MHz, Acetone-d6) δ7.63-7.69 (m, 1H), 7.21-7.47 (m, 6H), 7.00-7.10 (m, 2H), 5.32-5.45 (m, 1H), 4.43-4.66 (m, 2H), 3.67-3.90 (m, 2H), 3.02 (s, 3H); EI MS m/z=277 [C19H19NO]+; [α]25D−17° (c 1.0, MeOH, free base).

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