反应详情

To a stirred suspension of 5-chloro-2-hydroxybenzaldehyde (5.0 g, 32.1 mmol) and K2CO3 (4.87 g, 35.3 mmol) in DMF (20 mL), bromoacetaldehyde diethyl acetal (5.43 mL, 35.3 mmol) was added dropwise. The mixture was refluxed for 4 h. After cooling, the precipitate was filtered off and the solvent was evaporated in vacuo. The crude residue was adsorbed on silica gel and purified by flash chromatography. The product was eluted with hexane/EtOAc (4:1) to give 33 (4.10 g, 38%) as an oil. 1H NMR (500 MHz, CDCl3): δ: 10.42 (1H, s, CHO), 7.76 (1H, d, J=2.8 Hz, ArH), 7.46 (1H, dd, J=6.15 & 2.75 Hz, ArH), 6.96 (1H, d, J=8.90 Hz, ArH), 4.87 (1H, t, J=5.25 Hz, CH), 4.10 (2H, d, J=5.25 Hz, CH2), 3.80-3.77 (2H, m, CH2CH3), 3.67-3.62 (2H, m, CH2CH3), 1.24 (6H, t, J=7.05 Hz, 2×CH3).

1. additionwas added dropwise
2. temperatureThe mixture was refluxed for 4 h
3. temperatureAfter cooling
4. filtrationthe precipitate was filtered off
5. customthe solvent was evaporated in vacuo
6. custompurified by flash chromatography
7. washThe product was eluted with hexane/EtOAc (4:1)