反应详情

To a stirred refluxing solution of 3,4,5-trimethoxybenzaldehyde (17.0 g, 86.6 mmol) in water (3 mL) and chloroform (100 mL) was added a solution of bromine (14.7 g, 92 mmol) in chloroform (30 mL) dropwise. The solution was heated under reflux overnight, cooled, washed with water (2×100 mL) and saturated aqueous sodium hydrogen carbonate (50 mL), dried over MgSO4, filtered and evaporated. The residual orange oil (27 g) crystallised on standing. The solid was washed with petroleum ether, b.p. 40-60° C., to obtain 2-bromo-3,4,5-trimethoxybenzaldehyde as white crystals (23.4 g, 98%); m.p. 69° C. (literature value 69.5-71° C., see Brown, E.; Robin, J.-P.; Dhal, R. Tetrahedron 1982, 38, 2569-2579); NMR Spectrum δH (300 MHz, CDCl3) 10.40 (1H, s, 1-CHO), 7.29 (1H, s, 6-H), 4.00 (3H, s, OCH3), 3.95 (3H, s, OCH3) and 3.93 (3H, s, OCH3); NMR Spectrum δC (75 MHz, CDCl3) 56.6, 61.6, 106.9, 126.1, 128.1, 149.2, 150.3, 152.8, 189.2; νmax/cm−1 (thin film) 2940, 2843, 1685 (C═O), 1588, 1480, 1460, 1386, 1317, 1196, 1161, 1134, 1103 and 1002 (data in accordance with published values, see Brown, E.; Robin, J.-P.; Dhal, R. Tetrahedron 1982, 38, 2569-2579); Rf(hexane-ethyl acetate 4:1) 0.50.

1. temperatureThe solution was heated
2. temperatureunder reflux overnight
3. temperaturecooled
4. washwashed with water (2×100 mL) and saturated aqueous sodium hydrogen carbonate (50 mL)
5. dry with materialdried over MgSO4
6. filtrationfiltered
7. customevaporated
8. customThe residual orange oil (27 g) crystallised
9. washThe solid was washed with petroleum ether, b.p. 40-60° C.