p-Toluenesulfonic acid → HCID 54550531, compound

HRID 37436Notes

Reaction equation

HRID 37436 reaction equation
[Mg].C(Cl)[C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=1.[CH3:10][C:11]1([CH3:24])[C:16]2[CH:17]=[CH:18][C:19]([C:21](=O)[CH3:22])=[CH:20][C:15]=2[O:14][CH2:13][CH2:12]1.[C:25]1(C)C=CC(S(O)(=O)=O)=CC=1>CCOCC.C(O)(=O)C.O>[CH3:10][C:11]1([CH3:24])[C:16]2[CH:17]=[CH:18][C:19]([C:21]([CH3:25])=[CH:22][C:3]3[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=3)=[CH:20][C:15]=2[O:14][CH2:13][CH2:12]1

Participants

8

Reactant 4

HCID 6101p-Toluenesulfonic acidHCID 7503Benzyl ChlorideHCID 5462224Magnesium2×HCID 19935426HCID 19935426, compound

Product 1

HCID 54550531HCID 54550531, compoundYield 593.8%

Reagents, catalysts & solvents 3

HCID 176Acetic AcidSolventHCID 962WaterSolventHCID 3283Diethyl EtherSolvent3×

Procedure

1.7 g of magnesium shavings were covered with 10 ml of ether. A solution of 7.7 g of benzyl chloride in 80 ml of ether was added dropwise thereto under slight reflux and the mixture was subsequently held at boiling for an additional hour until the magnesium had dissolved completely. After cooling to room temperature, a solution of 7 g of 3,4-dihydro-4,4-dimethyl-7-acetyl-2H-1-benzopyran in 50 ml of ether was added dropwise and the reaction mixture was heated under reflux for an additional 2.5 hours. After cooling, the mixture was poured on to ice/2N hydrochloric acid and extracted with ether. The organic phase was washed with water and dilute sodium bicarbonate solution, dried and evaporated. The thus-obtained slightly yellow oil was dissolved in 10 ml of acetic acid and, after the addition of 0.5 g of p-toluenesulfonic acid, heated under reflux for 2 hours. The reaction solution obtained was diluted with water and extracted several times with ether. The combined extracts were diluted with water, washed with sodium bicarbonate solution and water, dried and evaporated. The crude product was chromatographed (silica gel, eluting agent hexane/0.5% ethyl acetate) and recrystallized from hexane. There were obtained 4.8 g of 3,4-dihydro-4,4-dimethyl-7-(α-methylstyryl)-2H-1-benzopyran, melting point 44°-46° C.

Workup

  1. temperatureunder slight reflux
  2. dissolutionhad dissolved completely
  3. temperaturethe reaction mixture was heated
  4. temperatureunder reflux for an additional 2.5 hours
  5. temperatureAfter cooling
  6. extractionextracted with ether
  7. washThe organic phase was washed with water and dilute sodium bicarbonate solution
  8. customdried
  9. customevaporated
  10. customThe thus-obtained slightly yellow oil
  11. temperatureheated
  12. temperatureunder reflux for 2 hours
  13. customThe reaction solution obtained
  14. extractionextracted several times with ether
  15. additionThe combined extracts were diluted with water
  16. washwashed with sodium bicarbonate solution and water
  17. customdried
  18. customevaporated
  19. customThe crude product was chromatographed
  20. wash(silica gel, eluting agent hexane/0.5% ethyl acetate)
  21. customrecrystallized from hexane

Sources & evidence

ORD record
ord-47acde9ce9eb4ab8846291c554368f25
Source dataset
uspto-grants-1995_05
Patent number
US05420273

Reaction notes

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