3,6-Dimethoxyphthalic anhydride → 4,7-Dimethoxyphthalide

HRID 437983Notes

Reaction equation

HRID 437983 reaction equation
[BH4-].[Na+].[CH3:3][O:4][C:5]1[CH:15]=[CH:14][C:13]([O:16][CH3:17])=[C:7]2[C:8]([O:10][C:11](=O)[C:6]=12)=[O:9]>>[CH3:3][O:4][C:5]1[CH:15]=[CH:14][C:13]([O:16][CH3:17])=[C:7]2[C:6]=1[CH2:11][O:10][C:8]2=[O:9]

Participants

3

Reactant 2

HCID 27525923,6-Dimethoxyphthalic anhydrideHCID 4311764Sodium borohydride

Product 1

HCID 37032364,7-Dimethoxyphthalide

Procedure

To an ice-cold solution of 1.7 g. of sodium borohydride in 100 ml. of dimethylformide is added 9.2 g. of 3,6-dimethoxyphthalic anhydride. The cold bath is removed and the mixture stirred for one hour. The mixture is cooled in ice and 20 ml. of hydrochloric acid is slowly added. The solvent is removed in vacuo and the residue is slurried in 100 ml. of water. The resulting solid is filtered, dissolved in chloroform and dried. After removal of solvent, the solid is recrystallized from toluene to yield 4,7-dimethoxyphthalide with a melting point of 168°-170° C.

Workup

  1. additionof dimethylformide is added 9.2 g
  2. customThe cold bath is removed
  3. temperatureThe mixture is cooled in ice
  4. additionof hydrochloric acid is slowly added
  5. customThe solvent is removed in vacuo
  6. filtrationThe resulting solid is filtered
  7. dissolutiondissolved in chloroform
  8. customdried
  9. customAfter removal of solvent
  10. customthe solid is recrystallized from toluene

Sources & evidence

ORD record
ord-1df4e11113244afd967fb7dc36d20f6e
Source dataset
uspto-grants-1977_06
Patent number
US04032656

Reaction notes

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