Ethyl 7-hydroxychromane-2-carboxylate → HCID 14541247, compound

HRID 2231914Notes

Reaction equation

HRID 2231914 reaction equation
[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([CH2:6][CH2:7][CH:8]([C:12]([O:14]CC)=[O:13])[O:9]2)=[CH:4][CH:3]=1.[C:17](OC(=O)C)(=[O:19])[CH3:18].N1C=CC=CC=1>>[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([CH2:6][CH2:7][CH:8]([C:12]([OH:14])=[O:13])[O:9]2)=[CH:4][C:3]=1[C:17](=[O:19])[CH3:18]

Participants

3

Reactant 2

HCID 11085381Ethyl 7-hydroxychromane-2-carboxylateHCID 22348678Acetic anhydride pyridine

Product 1

HCID 14541247HCID 14541247, compound

Procedure

A 1.1 g sample of racemic ethyl 7-hydroxychroman-2-carboxylate was treated with 10 ml of 1:1 acetic anhydride-pyridine and stirred for 17 hours at room temperature. After removal of the solvents, the residual product (1.2 g) was dissolved in 12 ml of glacial acetic acid and treated with 1.26 ml of borontrifluoride etherate. The reaction mixture was gently refluxed for 17 hours, cooled, poured carefully into a mixture of sodium bicarbonate and ice and the product extracted with 1:1 tetrahydrofuran-ether. After evaporation of the solvent, 1.1 g of crude racemic-7-hydroxy-6-acetylchroman-2-carboxylic acid was obtained. Conversion of this material into the corresponding ethyl ester was achieved by refluxing 1.1 g of the crude acid in absolute ethanol in the presence of 10 mg of p-toluenesulfonic acid for 17 hours. After removal of most of the solvent, the product was extracted with 1:1 tetrahydrofuran-ether, washed with saturated sodium bicarbonate solution, water, dried and the solvents concentrated to give 1.2 g of crude ethyl ester as a mixture of the 6-acetyl and 8-acetyl derivatives in a ratio of about 7:1. This material was purified by column chromatography on silica gel to afford 0.7 g (53.5%) of racemic-6-acetyl-3,4-dihydro-7-hydroxy-2H-1-benzopyran-2-carboxylic acid ethyl ester as a colorless crystalline material mp 93.5°-95.5° C. (from ethyl acetate-hexane).

Workup

  1. customAfter removal of the solvents
  2. dissolutionthe residual product (1.2 g) was dissolved in 12 ml of glacial acetic acid
  3. additiontreated with 1.26 ml of borontrifluoride etherate
  4. temperatureThe reaction mixture was gently refluxed for 17 hours
  5. temperaturecooled
  6. additionpoured carefully into a mixture of sodium bicarbonate and ice
  7. extractionthe product extracted with 1:1 tetrahydrofuran-ether
  8. customAfter evaporation of the solvent

Sources & evidence

ORD record
ord-2b4323bd260a4cfb92b4fcb8751f2faa
Source dataset
uspto-grants-1988_11
Patent number
US04785017

Reaction notes

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