Chromocarb → 3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

HRID 1004634Notes

Reaction equation

HRID 1004634 reaction equation
O=[C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[O:5][C:4]([C:12]([OH:14])=[O:13])=[CH:3]1>[Pd].C(O)(=O)C.C(OCC)(=O)C>[O:5]1[C:6]2[C:11](=[CH:10][CH:9]=[CH:8][CH:7]=2)[CH2:2][CH2:3][CH:4]1[C:12]([OH:14])=[O:13]

Participants

5

Reactant 1

HCID 2741Chromocarb

Product 1

HCID 27236653,4-dihydro-2H-1-benzopyran-2-carboxylic acidYield 96.2%

Reagents, catalysts & solvents 3

HCID 23938PalladiumCatalystHCID 176Acetic AcidSolventHCID 8857Ethyl AcetateSolvent

Procedure

A mixture of the compound from Example 19 (20.0 g, 105 mmol), and palladium on activated carbon (Pd 10%, 2.0 g) in acetic acid (200 mL) was placed under hydrogen pressure (60 psig) in a Parr hydrogenation apparatus. After 22.5 hours the mixture was removed from the hydrogen atmosphere and filtered through a pad of Celite. The Celite pad was washed with ethyl acetate (800 mL), and the combined filtrate concentrated to give a brown oil. The oil was dissolved in ethyl acetate (500 mL) and extracted with saturated aqueous NaHCO3 solution (4×125 mL). The aqueous phase was acidified to pH=2 with concentrated HCl and extracted with ethyl acetate (4×100 mL). The combined organic phase was washed with saturated aqueous sodium chloride solution (100 mL), dried (MgSO4), and concentrated to give a colorless solid (18.0 g, 96%). Mp 97.5-99° C.; 1H NMR (DMSO-d6, 300 MHz) δ 12.96 (br s, 1 H), 7.03 (m, 2 H), 6.78 (m, 2 H), 4.74 (dd, J=6.4 Hz, 3.9 Hz, 1 H), 2.73 (m, 1 H), 2.63 (m, 1 H), 2.03 (m, 2 H).

Workup

  1. customAfter 22.5 hours the mixture was removed from the hydrogen atmosphere
  2. filtrationfiltered through a pad of Celite
  3. washThe Celite pad was washed with ethyl acetate (800 mL)
  4. concentrationthe combined filtrate concentrated
  5. customto give a brown oil
  6. extractionextracted with saturated aqueous NaHCO3 solution (4×125 mL)
  7. extractionextracted with ethyl acetate (4×100 mL)
  8. washThe combined organic phase was washed with saturated aqueous sodium chloride solution (100 mL)
  9. dry with materialdried (MgSO4)
  10. concentrationconcentrated

Sources & evidence

ORD record
ord-fd7427a4e6e3411e83c89a2d9930be2f
Source dataset
uspto-grants-2000_04
Patent number
US06051586

Reaction notes

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