反应详情

To a suspension of 2.0 g sodium hydride in 100 ml of dry tetrahydrofuran is added with stirring a solution of 20 g of trans-3-bromo-4-hydroxy-6-methoxy-3,4-dihydro-2H-[1]-benzopyran in 200 ml of dry tetrahydrofuran in a dropwise fashion. Afer 30 minutes stirring at room temperature, the reaction mixture is filtered through filter-cel and the solvent is removed in vacuo. The residue is dissolved in 100 ml of toluene, 1.0 g of anhydrous zinc iodide is added and the mixture is heated at 80° for 1 hour. The reaction mixture is filtered through 120 g of silica gel with methylene chloride as the eluent to afford a product which is recrystallized from ether to give 6-methoxy-2H-[1]-benzopyran-3-one, melting point 67°-72°.

1. additionis added
2. filtrationthe reaction mixture is filtered
3. filtrationthrough filter-cel
4. customthe solvent is removed in vacuo
5. dissolutionThe residue is dissolved in 100 ml of toluene
6. addition1.0 g of anhydrous zinc iodide is added
7. temperaturethe mixture is heated at 80° for 1 hour
8. filtrationThe reaction mixture is filtered through 120 g of silica gel with methylene chloride as the eluent
9. customto afford a product which
10. customis recrystallized from ether