反应详情

para-Nitrophenol (0.95 g), 4-dimethylaminopyridine (80 mg) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.4 g) were added to a stirred suspension of 4-difluoromethoxy-2-ethylbenzooxazole-7-carboxylic acid (1.6 g) in dry dichloromethane (60 ml) under an atmosphere of nitrogen. The reaction mixture was stirred at room temperature for 18 hours. Water (20 ml) was added and the aqueous layer extracted with dichloromethane (400 ml). The organic layer was washed with water (80 ml), separated, dried over magnesium sulphate, filtered and the solvent removed in vacuo. Purification by column chromatography on silica eluting with 1:4 ethyl acetate/heptane to 1:1:2 ethyl acetate/dichloromethane/heptane afforded the title compound as a pale yellow solid (1.9 g)

1. extractionthe aqueous layer extracted with dichloromethane (400 ml)
2. washThe organic layer was washed with water (80 ml)
3. customseparated
4. dry with materialdried over magnesium sulphate
5. filtrationfiltered
6. customthe solvent removed in vacuo
7. customPurification by column chromatography on silica eluting with 1:4 ethyl acetate/heptane to 1:1:2 ethyl acetate/dichloromethane/heptane