p-Toluenesulfonic acid monohydrate → 2-(4,5-Dimethoxy-2-hydroxyphenyl)-4-(2-pyridylmethyl) aminomethylbenzoxazole

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Reaction Steps

A mixture of 7 (100 mg, 0.23 mmol) and p-toluenesulfonic acid monohydrate (190 mg, 1 mmol) in methanol (20 mL) was stirred overnight at room temperature. After the solvent was evaporated, ethyl acetate (20 mL) was added to the resulting residue which was neutralized by Na2CO3, washed with brine and water, dried over MgSO4, and concentrated in vacuo to give a pale yellow solid that was purified by silica gel column chromatography (ethyl acetate) and crystallized from ethanol to afford a white solid of Zinbo-5 (80 mg, 89%): 1H-NMR (500 MHz, CDCl3) δ3.95 (s, 3H), 3.96 (s, 3H), 4.01 (s, 2H), 4.21 (s, 2H), 6.66 (s, 1H), 7.17 (dd, 1H, J=7.5, 5.0 Hz), 7.31 (t, 1H, J=8.0 Hz), 7.37–7.40 (m, 2H), 7.41 (s, 1H), 7.48 (d, 1H, J=8.0 Hz),7.67 (t, 1H, J=7.5 Hz), 8.66 (d, 2H, J=5.0 Hz), 11.27 (s, 1H); Anal. Calcd for C22H21N3O4: C, 67.51; H, 5.41; N, 10.74. Found: C, 67.12; H, 5.25; N, 10.57.

Provenance & Evidence