Phosphorus oxychloride → 2-benzylthio-7-chloro-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-one

HRID 703835Notes

Reaction equation

HRID 703835 reaction equation
[CH2:1]([S:8][C:9]1[S:19][C:12]2=[N:13][C:14](O)=[CH:15][C:16](=[O:17])[N:11]2[N:10]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.P(Cl)(Cl)(Cl)(Cl)[Cl:21].P(Cl)(Cl)(Cl)=O>>[CH2:1]([S:8][C:9]1[S:19][C:12]2=[N:13][C:14]([Cl:21])=[CH:15][C:16](=[O:17])[N:11]2[N:10]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

4

Reactant 3

HCID 24813Phosphorus oxychlorideHCID 24819Phosphorus pentachlorideHCID 1355943712-(Benzylthio)-7-hydroxy-5H-1,3,4-thiadiazolo(3,2-a)pyrimidin-5-one

Product 1

HCID 142544242-benzylthio-7-chloro-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-oneYield 25%

Procedure

A mixture of 31.7 g of the thus obtained 2-benzylthio-7-hydroxy-5H-1,3,4-thiadiazolo[3,2-a]-pyrimidin-5-one, 24.0 g of phosphorus pentachloride and 117 g of phosphorus oxychloride was heated to 70°-80° C. and stirred for 25 minutes. After cooling, the reaction mixture was concentrated under reduced pressure and chloroform and water were added to the residue. The organic layer was washed with an aqueous sodium hydrogen carbonate solution and water, and dried over anhydrous sodium sulfate. The solvent was distilled off and the residue was separated by silica gel column chromatography using an ethyl acetate/hexane mixture as an eluent, and thus 8.5 g of 2-benzylthio-7-chloro-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-one was obtained. m.p. 138°-140° C. Yield 25%.

Workup

  1. temperaturewas heated to 70°-80° C.
  2. temperatureAfter cooling
  3. concentrationthe reaction mixture was concentrated under reduced pressure and chloroform and water
  4. additionwere added to the residue
  5. washThe organic layer was washed with an aqueous sodium hydrogen carbonate solution and water
  6. dry with materialdried over anhydrous sodium sulfate
  7. distillationThe solvent was distilled off
  8. customthe residue was separated by silica gel column chromatography

Sources & evidence

ORD record
ord-184e950f863a4ecca58f75b2a2f93a6a
Source dataset
uspto-grants-1991_01
Patent number
US04985432

Reaction notes

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