4H-1-Benzopyran-2-carboxylic acid, 6-hydroxy-4-oxo-, ethyl ester → ethyl 3,4-dihydro-6-hydroxy-2H-1-benzopyran-2-carboxylate
Reaction equation
[OH:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][C:7]([C:12]([O:14][CH2:15][CH3:16])=[O:13])=[CH:6][C:5]2=O>C(O)(=O)C.[Pd]>[CH2:15]([O:14][C:12]([CH:7]1[CH2:6][CH2:5][C:4]2[CH:3]=[C:2]([OH:1])[CH:11]=[CH:10][C:9]=2[O:8]1)=[O:13])[CH3:16]Participants
4
Procedure
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.
Workup
- filtrationThe catalyst was filtered
- customthe filtrate was evaporated under reduced pressure
- customto give 7.85 g of crude material
- customPurification of this compound by high-performance liquid chromatography (solvent system, hexane-ethyl acetate 3:1)
Sources & evidence
- ORD record
- ord-f16f5e4f787b4e60af9c0dbf8e22c51e
- Source dataset
- uspto-grants-1988_11
- Patent number
- US04788214
Reaction notes
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