Cesium carbonate → 6-(4-Bromo-3-formyl-phenoxy)-pyridine-2,3-dicarboxylic acid dimethyl ester

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Reaction Conditions

Reaction Steps

To a solution of 6-chloro-pyridine-2,3-dicarboxylic acid dimethyl ester (18, 4.0 g, 17.42 mmols) and 2-bromo-5-hydroxy-benzaldehyde (3.5 g, 17.42 mmol) in DMF (30 mL) was added cesium carbonate (11.35 g, 34.84 mmols). The resulting mixture was heated at 80° C. overnight. DMF was removed under reduced pressure, diluted with EtOAc (100 mL), washed with water (2×25 mL) and brine (50 mL) solution. The combined organic layers were dried over Na2SO4, filtered, and concentrated to give crude product which was purified by column chromatography (Silica gel 20% EtOAc in hexane) to yield title compound 19 (1.14 g, 15%) as a light yellow oil. 1H NMR 400 MHz (DMSO-d6) δ: 10.18 (s, 1H), 8.38 (d, J=8.6 Hz, 1H), 7.90 (d, J=8.5 Hz, 1H), 7.66 (s, 1H), 7.55-7.52 (m, 1H), 7.36 (d, J=8.6 Hz, 1H), 3.86 (s, 3H), 3.84 (s, 3H); MS (ES) m/z: 394 (M+1)+, 396 (M+3)+.

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