反应详情

A solution of sodium nitrite (1.67 g, 24.2 mmol) in water (14 mL) is added dropwise to an ice cold mixture of ethyl 4-aminobenzoate (4.0 g, 24.2 mmol) and tetrafluoroboric acid (7.8 mL, 48%, 59.78 mmol) and stirred for 30 min. Methanol (28.5 mL), 2,5-dihydrofuran (3.66 mL, 48.4 mmol) and palladium(II) acetate (70 mg, 0.31 mmol) are added and the mixture refluxed for 30 min. The mixture is filtered through Celite® pad and the filtrate diluted with dichloromethane (100 mL). The organic layer is separated and concentrated in vacuo. The residue is chromatographed on SiO2 (10% ethyl acetate/hexanes) to yield the title compound, 2.45 g (42%), as a white solid.

1. temperaturethe mixture refluxed for 30 min
2. filtrationThe mixture is filtered through Celite® pad
3. additionthe filtrate diluted with dichloromethane (100 mL)
4. customThe organic layer is separated
5. concentrationconcentrated in vacuo
6. customThe residue is chromatographed on SiO2 (10% ethyl acetate/hexanes)