5-Methoxy-2H-1-benzopyran-3-carboxylic acid → 5-Methoxy-3,4-dihydro-2H-chromene-3-carboxylic acid

HRID 963996Notes

Reaction equation

HRID 963996 reaction equation
[CH3:1][O:2][C:3]1[C:8]2[CH:9]=[C:10]([C:13]([OH:15])=[O:14])[CH2:11][O:12][C:7]=2[CH:6]=[CH:5][CH:4]=1.[H][H]>[Pd].C(O)C>[CH3:1][O:2][C:3]1[C:8]2[CH2:9][CH:10]([C:13]([OH:15])=[O:14])[CH2:11][O:12][C:7]=2[CH:6]=[CH:5][CH:4]=1

Participants

5

Reactant 2

HCID 139289475-Methoxy-2H-1-benzopyran-3-carboxylic acidHCID 178418361HCID 178418361, compound

Product 1

HCID 111172575-Methoxy-3,4-dihydro-2H-chromene-3-carboxylic acid

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 702EthanolSolvent

Procedure

A mixture of 5-methoxy-2H-1-benzopyran-3-carboxylic acid (12.25 g, prepared in a similar manner to that described above), 10% palladium-on-carbon catalyst (3 g) and ethanol (250 ml) was hydrogenated at 1 atmosphere for 1 hour. Hydrogen uptake was slow, so further catalyst (3 g) was added, and hydrogenation continued for 5 hours. The mixture was filtered and the solvent removed in vacuo to leave a semisolid which crystallised from 2-propanol to give a mass of pale yellow crystals which was broken up, collected by filtration, washed with ice-cold 2-propanol, dried in vacuo, ground to a powder, and redried in vacuo to give 5-methoxy-3,4-dihydro-2H-1-benzopyran-3-carboxylic acid as a buff powder (7.4 g), m.p. 147°-150° C.

Workup

  1. customprepared in a similar manner to that
  2. waithydrogenation continued for 5 hours
  3. filtrationThe mixture was filtered
  4. customthe solvent removed in vacuo
  5. customto leave a semisolid which
  6. customcrystallised from 2-propanol
  7. customto give a mass of pale yellow crystals which
  8. filtrationcollected by filtration
  9. washwashed with ice-cold 2-propanol
  10. customdried in vacuo, ground to a powder
  11. customredried in vacuo

Sources & evidence

ORD record
ord-c663e6e474e64efc8ab97291847e0571
Source dataset
uspto-grants-1998_06
Patent number
US05767116

Reaction notes

Loading…