Tetrahydrofuran → 5-methoxy-3,4-dihydro-2H-1-benzopyran-3-one

Participants

Reaction Steps

To a suspension of 5.0 g sodium hydride in 100 ml of dry tetrahydrofuran is added with stirring a solution of 13 g of trans-3-bromo-4-hydroxy-5-methoxy-3,4-dihydro-2H-[1]benzopyran in 150 ml of dry tetrahydrofuran in a dropwise fashion. After 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 150 ml of toluene, 1.0 g of anhydrous zinc iodide is added and the mixture is refluxed for 15 minutes. The reaction mixture is filtered through 120 g of silica gel with methylene chloride as the eluent to afford 5-methoxy-3,4-dihydro-2H-[1]-benzopyran-3-one (5-methoxychroman-3-one) as an oil.

Provenance & Evidence