反应详情

To a solution of ethyl 3-methyl-4-hydroxy-5-tert-butylbenzofuran-2-carboxylate, compound 12a (1.00 g, 3.62 mmol) and p-chlorobenzoyl chloride (0.793 g, 4.53 mmol) in 1,2-dichloroethane (40 mL) at 0° C. was added aluminum chloride (0.604 g, 4.53 mmol) and the mixture heated to reflux for two hours. Additional portions of 4-chlorobenzoyl chloride (0.475 g, 2.71 mmol) and aluminum chloride (0.362 g, 2.71 mmol) were added and the reflux continued for an additional 1.5 hours. The reaction mixture was poured into 2N HCl (100 mL) and extracted with methylene chloride (4×25 mL). The combined extracts were washed with water (25 mL), dried (Na2SO4), and concentrated. Flash chromatography using 25% ethyl acetate in hexane as eluant afforded ethyl 3-methyl-4-hydroxy-5-tert-butyl-7-p-chlorobenzoylbenzofuran-2-carboxylate, compound 17 as an oil sufficiently pure for further chemistry. 1H NMR d 1.34 (3H, t, J=6 Hz), 1.50 (9H, s), 2.88 (3H, s), 4.54 (2H, q, J=6 Hz), 7.47 (2H, d, J=8 Hz), 7.78 (2H, d, J=8 Hz), 7.87 (1H, s).

1. temperaturethe mixture heated
2. temperatureto reflux for two hours
3. extractionextracted with methylene chloride (4×25 mL)
4. washThe combined extracts were washed with water (25 mL)
5. dry with materialdried (Na2SO4)
6. concentrationconcentrated