Ethyl formate → 3-(Hydroxymethylidene)-2,3-dihydro-4H-1-benzothiopyran-4-one

HRID 903557Notes

Reaction equation

HRID 903557 reaction equation
[Na].C[O-].[Na+].[CH:5](OCC)=[O:6].[S:10]1[C:15]2[CH:16]=[CH:17][CH:18]=[CH:19][C:14]=2[C:13](=[O:20])[CH2:12][CH2:11]1>C1C=CC=CC=1.CO>[OH:6][CH:5]=[C:12]1[C:13](=[O:20])[C:14]2[CH:19]=[CH:18][CH:17]=[CH:16][C:15]=2[S:10][CH2:11]1

Participants

7

Reactant 4

HCID 8025Ethyl formateHCID 19048Thiochroman-4-oneHCID 5360545SodiumHCID 10942334Sodium Methoxide

Product 1

HCID 705949643-(Hydroxymethylidene)-2,3-dihydro-4H-1-benzothiopyran-4-one

Reagents, catalysts & solvents 2

HCID 241BenzeneSolvent2×HCID 887MethanolSolvent2×

Procedure

From 9.2 g of sodium (0.4 mol) and 160 ml of absolute methanol there is prepared sodium methanolate. Then the surplus of methanol is evaporated in vacuo and 200 ml of dry benzene and 32.6 g of ethyl formate (0.44 mol) are added to the dry residue. While stirring and passing nitrogen through the mixture, there are added 32.8 g of 2,3-dihydro-4H-1-benzothiopyran-4-one, dissolved in 160 ml of dry benzene dropwise to it to keep the reaction temperature in the range from 0° to 50° C. All components become dissolved and after that, the sodium salt of the 2,3-dihydro-3-(hydroxymethylene)-4H-1-benzothiopyran-4-one precipitates. After allowing the reaction mixture to stand overnight at room temperature, 400 ml of water are added for dissolving the sodium salt. The aqueous layer is separated from the organic solvent and, after agitating twice with ether and treatment with charcoal, it is acidified with half-concentrated aqueous hydrochloric acid. The oily title compound is extracted with chloroform, dried with sodium sulphate and after evaporation of the solvent, distilled in vacuo. b.p. 0.3 mm, 134°-138°; yield: 32.9 g (85.6%).

Workup

  1. additionare added to the dry residue
  2. customfrom 0° to 50° C
  3. dissolutionAll components become dissolved
  4. customafter that, the sodium salt of the 2,3-dihydro-3-(hydroxymethylene)-4H-1-benzothiopyran-4-one precipitates
  5. addition400 ml of water are added
  6. dissolutionfor dissolving the sodium salt
  7. customThe aqueous layer is separated from the organic solvent
  8. stirringafter agitating twice with ether and treatment with charcoal, it
  9. extractionThe oily title compound is extracted with chloroform
  10. dry with materialdried with sodium sulphate
  11. customafter evaporation of the solvent
  12. distillationdistilled in vacuo
  13. customb.p. 0.3 mm, 134°-138°

Sources & evidence

ORD record
ord-b048baaa9b80466aad2763e94975fd79
Source dataset
uspto-grants-1980_10
Patent number
US04228177

Reaction notes

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