Hydrochloric Acid → 2,3-Dihydro-8-methoxy-4H-1-benzothiopyran-4-one

HRID 864951Notes

Reaction equation

HRID 864951 reaction equation
P(Cl)(Cl)(Cl)(Cl)Cl.[CH3:7][O:8][C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[S:15][CH2:16][CH2:17][C:18]([OH:20])=O.Cl>C1C=CC=CC=1>[CH3:7][O:8][C:9]1[CH:14]=[CH:13][CH:12]=[C:11]2[C:10]=1[S:15][CH2:16][CH2:17][C:18]2=[O:20]

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 24819Phosphorus pentachlorideHCID 4604295HCID 4604295, compound

Product 1

HCID 64553542,3-Dihydro-8-methoxy-4H-1-benzothiopyran-4-oneYield 76%

Reagents, catalysts & solvents 1

HCID 241BenzeneSolvent

Conditions

Temperature
0 °C

Procedure

8.64 g of phosphorous pentachloride was added to a solution of 8.0 g of 2-(2-methoxyphenylthio)ethanecarboxylic acid in 24 ml of benzene under the atmosphere of argon while cooling to 0° C. After stirring the reaction mixture for 20 minutes at 100° C., 9.13 ml of stannous tetrachloride was dropwise added to the mixture while cooling to -10° C. Following completion of dropping, the reaction mixture was warmed to 0° C. and stirred for 30 minutes. Next, 24 g of ice followed by 14 ml of concentrated hydrochloric acid were added followed by refluxing for about 30 minutes. After cooling the reaction mixture to room temperature, the organic layer was separated and the aqueous layer was extracted three times with benzene. After combining the organic layers and washing twice with water, the combined organic layer was dried over magnesium sulfate, the solvent was distilled off and the resulting crystal was recrystallized from ethyl acetate-hexane to obtain 5.53 g of the target compound 8-methoxythiochroman-4-one (yield: 76%, m.p.: 110°-110.5° C.).

Workup

  1. temperaturewhile cooling to -10° C
  2. temperaturethe reaction mixture was warmed to 0° C.
  3. stirringstirred for 30 minutes
  4. additionwere added
  5. temperatureby refluxing for about 30 minutes
  6. temperatureAfter cooling the reaction mixture to room temperature
  7. customthe organic layer was separated
  8. extractionthe aqueous layer was extracted three times with benzene
  9. washwashing twice with water
  10. dry with materialthe combined organic layer was dried over magnesium sulfate
  11. distillationthe solvent was distilled off
  12. customthe resulting crystal was recrystallized from ethyl acetate-hexane

Sources & evidence

ORD record
ord-8df770277512455089a6ad020c694445
Source dataset
uspto-grants-1996_10
Patent number
US05565440

Reaction notes

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