Glyoxylic Acid → 3-Hydroxybenzofuran-2(3H)-one

HRID 430730Notes

Reaction equation

HRID 430730 reaction equation
O[C:2]1[C:3]2[C:8]([C:9]3C=CC=C[C:14]=3[CH:15]=1)=CC=CC=2.[C:16]([OH:20])(=[O:19])[CH:17]=[O:18]>ClCCCl.C1(C)C=CC(S(O)(=O)=O)=CC=1>[OH:18][CH:17]1[C:15]2[CH:14]=[CH:9][CH:8]=[CH:3][C:2]=2[O:19][C:16]1=[O:20]

Participants

5

Reactant 2

HCID 760Glyoxylic AcidHCID 102299-Phenanthrol

Product 1

HCID 145122453-Hydroxybenzofuran-2(3H)-oneYield 79.2%

Reagents, catalysts & solvents 2

HCID 6101p-Toluenesulfonic acidCatalystHCID 111,2-DichloroethaneSolvent

Procedure

4.9 g of 9-hydroxyphenanthrene, 4.1 g of 50% aqueous glyoxylic acid and 0.05 g of p-toluenesulfonic acid are heated for 2 h in 70 ml of 1,2-dichloroethane under a water separator. The precipitated solid is then cooled down, filtered off, washed with cold 1,2-dichloroethane and dried to leave 3.0 g of hydroxybenzofuranone, which is introduced in 20 ml of toluene as initial charge together with 1.5 ml of thionyl chloride and 3 drops of DMF and then gradually heated to 100° C. so that the evolution of HCl and SO2 remains lively, but still controllable. The reaction mixture is subsequently stirred at 100° C. for 1 h. About 20 ml of liquid are then distilled off to remove excess thionyl chloride. The residue is diluted with 10 ml of toluene and admixed at room temperature with 1.7 ml of triethylamine added dropwise. The thick blue reaction mixture is then refluxed for 2 h. The precipitated isoxindigo is filtered off after cooling down to room temperature, freed of the triethylamine hydrochloride by washing with water, dried and recrystallized from dichloromethane/ethanol to leave 1.3 g (47% of theory) of [3,3′]bi[1-oxacyclopenta[l]phenanthrenylidene]-2,2′dione of the formula:

Workup

  1. temperatureThe precipitated solid is then cooled down
  2. filtrationfiltered off
  3. washwashed with cold 1,2-dichloroethane
  4. customdried

Sources & evidence

ORD record
ord-b538c5b23c9d45a092966bf8d0b8f136
Source dataset
uspto-grants-2001_11
Patent number
US06323267B1

Reaction notes

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