反应详情

A 50 ml rbf was charged with 6-fluoro-3,4-dihydro-2H-chromen-2-carboxylic acid (10.0 g, 51.0 mmol), oxalyl chloride (9.71 g, 76.5 mmol) and dichloromethane (24.9 g) under nitrogen atmosphere at room temperature. The mixture was stirred for 17 h at room temperature and then concentrated in vacuo at 30° C. The residue was dissolved in toluene (75 ml) and stirred at rt. 4-nitrophenol (7.05 g, 51.02 mmol) was added to the reaction mixture, followed by pyridine (5 ml) over the period of 5 min. The slurry was heated to 80° C., stirred for 3 h at this temperature and then cooled to 25° C. The solid was separated by filtration and the filtered solution washed with 2M aqueous sodium hydroxide (65 g), with a saturated solution of sodium bicarbonate (2×51 g), and with demi water (53 g). The separated organic phase was concentrated in vacuo and dried via azeotropic distillation to furnish 4-nitrophenyl 6-fluoro-3,4-dihydro-2H-chromen-2-carboxylate as a vetrous oil (7.71 g, 40.5% yield, 85.0 A %).

1. concentrationconcentrated in vacuo at 30° C
2. dissolutionThe residue was dissolved in toluene (75 ml)
3. stirringstirred at rt
4. temperatureThe slurry was heated to 80° C.
5. stirringstirred for 3 h at this temperature
6. temperaturecooled to 25° C
7. customThe solid was separated by filtration
8. washthe filtered solution washed with 2M aqueous sodium hydroxide (65 g), with a saturated solution of sodium bicarbonate (2×51 g)
9. concentrationThe separated organic phase was concentrated in vacuo
10. customdried via azeotropic distillation