1,2-Dimethoxyethane → 2-Hydroxy-4-(2-methoxypyridin-3-yl)benzaldehyde

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Pd(PPh3)4 (9 g, 0.008 mol) was added to a degassed suspension of 4-bromo-2-hydroxybenzaldehyde (5, 34.2 g, 0.17 mol), 2-methoxypyridine-3-boronic acid (6, 28.5 g, 0.186 mol) and sodium carbonate (18.5 g) in 1,2-dimethoxyethane (420 mL) and water (140 mL) and heated at 80° C. for 16 h. The reaction mixture was cooled to room temperature and filtered through Celite. Celite was washed with chloroform (2×200 mL) and water (200 mL). The organic layer was separated and concentrated in vacuo to a residue which was re-crystallized from EtOAc/hexanes to obtain the desired 2-hydroxy-4-(2-methoxypyridin-3-yl)benzaldehyde (7a) after isolation by filtration (16.25 g). The filtrate from the recrystallization process was evaporated to dryness and the residue purified by flash chromatography (15% EtOAc/hexanes) to obtain the desired 2-hydroxy-4-(2-methoxypyridin-3-yl)benzaldehyde (11.87 g) in an overall yield of 28.12 g (72%). 1H NMR (C6D6) δ 11.06 (s, 1H), 9.95 (s, 1H), 8.18 (dd, J=4.98 Hz, 1.83 Hz, 1H), 7.29-7.71 (m, 2H), 7.60 (dd, J=7.29 Hz, 1.83 Hz, 1H), 7.08-6.96 (m, 2H), 3.99 (s, 3H).

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