Phosphorus oxychloride → Ethyl 4,5-dihydro-2-methyl-8-methylthiothieno[3,4-g]benzoxazole-6-carboxylate

HRID 1108341Notes

Reaction equation

HRID 1108341 reaction equation
[C:1]([NH:4][CH:5]1[CH2:20][CH2:19][C:8]2=[C:9]([C:14]([O:16][CH2:17][CH3:18])=[O:15])[S:10][C:11]([S:12][CH3:13])=[C:7]2[C:6]1=[O:21])(=O)[CH3:2].P(Cl)(Cl)(Cl)=O>C1(C)C=CC=CC=1>[CH3:2][C:1]1[O:21][C:6]2[C:7]3=[C:11]([S:12][CH3:13])[S:10][C:9]([C:14]([O:16][CH2:17][CH3:18])=[O:15])=[C:8]3[CH2:19][CH2:20][C:5]=2[N:4]=1

Participants

4

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 12043499Ethyl 5-acetylamino-4,5,6,7-tetrahydro-3-methylthio-4-oxobenzo[c]thiophene-1-carboxylate

Product 1

HCID 12043502Ethyl 4,5-dihydro-2-methyl-8-methylthiothieno[3,4-g]benzoxazole-6-carboxylateYield 94%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

A mixture of ethyl 5-acetylamino-4,5,6,7-tetrahydro-3-methylthio-4-oxobenzo[c]thiophene-1-carboxylate (2.46 g), phosphorus oxychloride (3.46 g) and toluene (80 ml) was refluxed under heating for 1.5 hours; the solution obtained was concentrated under reduced pressure, diluted with a saturated aqueous solution of sodium hydrogen carbonate (200 ml) and extracted with ethyl acetate. The organic layer was washed with water and dried (MgSO4), after which the solvent was distilled off to yield ethyl 4,5-dihydro-2-methyl-8-methylthiothieno[3,4-g]benzoxazole-6-carboxylate (2.18 g, 94.0%), which was then recrystallized from ethyl acetate-hexane. Light-yellow needles. Melting point 131-132° C.

Workup

  1. temperaturewas refluxed
  2. temperatureunder heating for 1.5 hours
  3. customthe solution obtained
  4. concentrationwas concentrated under reduced pressure
  5. additiondiluted with a saturated aqueous solution of sodium hydrogen carbonate (200 ml)
  6. extractionextracted with ethyl acetate
  7. washThe organic layer was washed with water
  8. dry with materialdried (MgSO4)
  9. distillationafter which the solvent was distilled off

Sources & evidence

ORD record
ord-a5e8fc667bd24970a9789fa90ae75a46
Source dataset
uspto-grants-2000_05
Patent number
US06066658

Reaction notes

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