反应详情

A solution of 8.75 g of ethyl 6-hydroxychromone-2-carboxylate in 200 ml of acetic acid was hydrogenated in the presence of 2 g of 10% palladium on charcoal at 50 psi and room temperature by shaking the suspension over a period of 17 hours. The catalyst was filtered and the filtrate was evaporated under reduced pressure to give 7.85 g of crude material. Purification of this compound by high-performance liquid chromatography (solvent system, hexane-ethyl acetate 3:1) yielded 4.9 g (59%) of pure crystalline racemic-3,4-dihydro-6-hydroxy-2H-1-benzopyran-2-carboxylic acid ethyl ester. Recrystallization from ethyl-acetate-hexane gave colorless solid, mp 72°-74° C.

1. filtrationThe catalyst was filtered
2. customthe filtrate was evaporated under reduced pressure
3. customto give 7.85 g of crude material
4. customPurification of this compound by high-performance liquid chromatography (solvent system, hexane-ethyl acetate 3:1)