4-Formylphenylboronic Acid → 7-[(2,4-Dichloro-5-methoxyphenyl)amino]-3-(4-formylphenyl)thieno[3,2-b]pyridine-6-carbonitrile

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A mixture of 3-bromo-7-[(2,4-dichloro-5-methoxyphenyl)amino]thieno[3,2-b]pyridine-6-carbonitrile (1.67 g, 3.89 mmol), 4-formylphenyl boronic acid (1.17 g, 7.78 mmol), and tetrakis(triphenylphosphine)pallidium (225 mg, 0.20 mmol) in 50 mL of ethylene glycol dimethyl ether and 42 mL of saturated aqueous sodium bicarbonate is heated at reflux for 2 hours and then cooled to room temperature. The precipitate is collected by filtration washing with ethyl acetate and diethyl ether to provide 1.09 g of 7-[(2,4-dichloro-5-methoxyphenyl)amino]-3-(4-formylphenyl)thieno[3,2-b]pyridine-6-carbonitrile as a tan solid, mp 268° C. dec; 1H NMR (DMSO-d6) δ 3.87 (s, 3H), 7.44 (s, 1H), 7.79 (s, 1H), 8.01 (d, J=8 Hz, 2H), 8.23 (d, J=8 Hz, 2H), 8.55 (s, 1H), 8.73 (s, 1H), 9.86 (s, 1H), 10.05 (s, 1H); MS 454.0, 456.0 (M+H)+; HRMS found: 454.01716 (M+H)+.

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