Diethyl Ether → ethyl 7-hydroxy-4-oxo-4H-chromen-2-carboxylate

HRID 1090775Notes

Reaction equation

HRID 1090775 reaction equation
[CH3:1][C:2]([C:4]1[CH:5]=[CH:6][C:7]([OH:11])=[CH:8][C:9]=1[OH:10])=[O:3].[Na].CCOCC.[CH2:18]([O:20][C:21](=[O:27])[C:22](OCC)=O)[CH3:19]>C(O)C>[C:21]([C:22]1[O:10][C:9]2[CH:8]=[C:7]([OH:11])[CH:6]=[CH:5][C:4]=2[C:2](=[O:3])[CH:1]=1)([O:20][CH2:18][CH3:19])=[O:27]

Participants

6

Reactant 4

HCID 3283Diethyl EtherHCID 69902',4'-DihydroxyacetophenoneHCID 7268Diethyl OxalateHCID 5360545Sodium

Product 1

HCID 5376802ethyl 7-hydroxy-4-oxo-4H-chromen-2-carboxylate

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Conditions

Temperature
100 °C

Procedure

A solution of 2,4-dihydroxyacetophenone (15.2g) in diethyloxalate (40 ml) is added with stirring to a solution of sodium (9.2g) in ethanol (200 ml). The mixture is then heated at 100° C. for 3.5 hours, cooled and is added to dry ether (500 ml). The mixture is allowed to sit overnight. The resulting precipitate is filtered off and dissolved in water, and the solution is neutralized with 4N hydrochloric acid and extracted with ether. The ether extracts are combined and are concentrated down in vacuo. The resulting residue is dissolved in ethanol (100ml) and concentrated hydrochloric acid is then added (2 ml). The solution is heated under reflux for 2 hours and is then concentrated in vacuo. The resulting solid is recrystallized in ethanol to give 2-carboethoxy-7-hydroxy-4-oxo-4H-1-benzopyran which is used directly in the next step.

Workup

  1. temperaturecooled
  2. filtrationThe resulting precipitate is filtered off
  3. dissolutiondissolved in water
  4. extractionextracted with ether
  5. concentrationare concentrated down in vacuo
  6. dissolutionThe resulting residue is dissolved in ethanol (100ml)
  7. additionconcentrated hydrochloric acid is then added (2 ml)
  8. temperatureThe solution is heated
  9. temperatureunder reflux for 2 hours
  10. concentrationis then concentrated in vacuo
  11. customThe resulting solid is recrystallized in ethanol

Sources & evidence

ORD record
ord-3025e462c83e40d6a9494d7d040671e0
Source dataset
uspto-grants-1992_01
Patent number
US05082849

Reaction notes

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