6-Methoxy-4-oxo-4H-1-benzopyran-2-carboxylic acid → 6-Methoxychroman-2-carboxylic acid

HRID 1906886Notes

Reaction equation

HRID 1906886 reaction equation
[CH3:1][O:2][C:3]1[CH:4]=[CH:5][C:6]2[O:11][C:10]([C:12]([OH:14])=[O:13])=[CH:9][C:8](=O)[C:7]=2[CH:16]=1.[H][H]>[Pd].C(O)(=O)C>[CH3:1][O:2][C:3]1[CH:4]=[CH:5][C:6]2[O:11][CH:10]([C:12]([OH:14])=[O:13])[CH2:9][CH2:8][C:7]=2[CH:16]=1

Participants

5

Reactant 2

HCID 149581966-Methoxy-4-oxo-4H-1-benzopyran-2-carboxylic acidHCID 178418361HCID 178418361, compound

Product 1

HCID 226283666-Methoxychroman-2-carboxylic acidYield 84.2%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 176Acetic AcidSolvent

Procedure

A mixture of 61 parts of 6-methoxy-4-oxo-4H-1-benzopyran-2-carboxylic acid and 500 parts of acetic acid was hydrogenated at normal pressure and at room temperature with 5 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen was taken up, the catalyst was filtered off and the filtrate was evaporated. The residue was stirred in petroleumether. The product was filtered off and dried in vacuo at about 65° C., yielding 49.1 parts (84.2%) of 3,4-dihydro-6-methoxy-2H-1-benzopyran-2-carboxylic acid; mp. 140° C. (intermediate 13).

Workup

  1. filtrationthe catalyst was filtered off
  2. customthe filtrate was evaporated
  3. filtrationThe product was filtered off
  4. customdried in vacuo at about 65° C.

Sources & evidence

ORD record
ord-faaa4fca1bcc47c3a3afd992537d94a8
Source dataset
uspto-grants-1987_03
Patent number
US04654362

Reaction notes

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