p-Toluenesulfonic acid → 4-methoxy-5,6-dihydro-2(1H)-pyridone

HRID 977938Notes

Reaction equation

HRID 977938 reaction equation
[O:1]=[C:2]1[CH2:7][C:6](=[O:8])[CH2:5][CH2:4][NH:3]1.[CH:9]([O-])([O-])OC.C1(C)C=CC(S(O)(=O)=O)=CC=1>CO>[CH3:9][O:8][C:6]1[CH2:5][CH2:4][NH:3][C:2](=[O:1])[CH:7]=1

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 108878632,4-PiperidinedioneHCID 53629101Methylorthoformate

Product 1

HCID 136065754-methoxy-5,6-dihydro-2(1H)-pyridoneYield 72.5%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

A mixture of 2,4-dioxopiperidine (15.1 g), methyl orthoformate (30 ml) and p-toluenesulfonic acid (3.0 g) in methanol (300 ml) is refluxed for 1 hour. After evaporating the solvent, the residue is dissolved in benzene and refluxed for 5 hours. To the solution is added potassium carbonate (9.0 g), and the mixture is stirred overnight at room temperature and then filtered. The filtrate is distilled to remove the solvent. The residue is recrystallized from ethyl acetate-isopropyl alcohol to give 4-methoxy-5,6-dihydro-2(1H)-pyridone (12.3 g, 72.5%) as colorless prisms. m.p. 115°-117° C.

Workup

  1. temperatureis refluxed for 1 hour
  2. customAfter evaporating the solvent
  3. dissolutionthe residue is dissolved in benzene
  4. temperaturerefluxed for 5 hours
  5. additionTo the solution is added potassium carbonate (9.0 g)
  6. filtrationfiltered
  7. distillationThe filtrate is distilled
  8. customto remove the solvent
  9. customThe residue is recrystallized from ethyl acetate-isopropyl alcohol

Sources & evidence

ORD record
ord-07dd26378622401482a3c266a001afea
Source dataset
uspto-grants-1987_05
Patent number
US04663319

Reaction notes

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