反应详情

A solution of 10.4 g of the methyl ester of 2H-1-benzopyran-3-carboxylic acid (Taylor et al., supra) in 50 ml of methanol containing 300 mg of 10% palladium-on-carbon catalyst was hydrogenated in a Parr apparatus for 1.5 hours, at an initial pressure of 44 psig. The mixture then was filtered through a Celite pad, the filtrate was stripped of solvent, and the product was vacuum distilled to give the methyl ester of 3,4-dihydro-2H-1-benzopyran-3-carboxylic acid (2A), as a colorless liquid, bp: 86°-88° C. (0.01 Torr.).

1. filtrationThe mixture then was filtered through a Celite pad
2. distillationdistilled