反应详情

To a degassed solution of 2-bromo-5-methoxybenzaldehyde (1.5 g, 7.04 mmol, Fluorochem) and trimethylboroxine (0.98 mL, 7.04 mmol) in 1,4-dioxane (80 mL) was added potassium carbonate (2.91 g, 21.1 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.813 g, 0.70 mmol). The mixture was heated under reflux for about 20 h, then more tetrakis(triphenylphosphine)palladium(0) (0.200 g, 0.17 mmol) and trimethylboroxine (0.25 mL, 1.8 mmol) were added and the mixture was heated under reflux for about another 3 h. After cooling to rt the mixture was filtered over diatomaceous earth and concentrated in vacuo. The residue was purified by column chromatography (SiO2, diethyl ether/hexanes 1:3) to give 5-methoxy-2-methyl-benzaldehyde (0.97 g, 92%) as a colorless liquid. 1H-NMR (CDCl3, Bruker 400 MHz) 2.60 (3 H, s); 3.83 (3 H, s); 7.04 (1 H, dd, J=8.5 Hz, 2.4 Hz); 7.16 (1 H, d, J=8.5 Hz); 7.33 (1 H, d, J=2.4 Hz); 10.2 (1 H, s).

1. temperatureThe mixture was heated
2. temperatureunder reflux for about 20 h
3. temperaturethe mixture was heated
4. temperatureunder reflux for about another 3 h
5. filtrationwas filtered over diatomaceous earth
6. concentrationconcentrated in vacuo
7. customThe residue was purified by column chromatography (SiO2, diethyl ether/hexanes 1:3)