Acetone → 6-methoxy-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

HRID 1684625Notes

Reaction equation

HRID 1684625 reaction equation
[CH3:1][C:2]([C:4]1[CH:9]=[C:8]([O:10][CH3:11])[CH:7]=[CH:6][C:5]=1[OH:12])=[O:3].[CH3:13][C:14]([CH3:16])=O.N1CCCC1.C(OCC)(=O)C>C1(C)C=CC=CC=1.N1CCCC1>[CH3:11][O:10][C:8]1[CH:9]=[C:4]2[C:5](=[CH:6][CH:7]=1)[O:12][C:14]([CH3:16])([CH3:13])[CH2:1][C:2]2=[O:3]

Participants

7

Reactant 4

HCID 180Acetone2×HCID 8857Ethyl AcetateHCID 31268PyrrolidineHCID 697141-(2-Hydroxy-5-methoxyphenyl)ethan-1-one

Product 1

HCID 125316266-methoxy-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-oneYield 53%

Reagents, catalysts & solvents 2

HCID 31268PyrrolidineCatalystHCID 1140TolueneSolvent

Procedure

A mixture of 48.9 g (0.294 mole) 2-hydroxy-5-methoxyacetophenone, 32 mL (0.441 mole) acetone and 12 mL (0.147 mmole) pyrrolidine in 300 mL toluene was stirred at room temperature for 3 hours, then refluxed over a Dean-Stark trap for 3 hours. An additional 32 mL (0.441 mole) acetone and 12 mL (0.147 mole) pyrrolidine was added and the mixture again refluxed over the Dean-Stark trap for 18 hours. The mixture was concentrated, poured into water, basified, and extracted with ether. The ether extract was, washed with 1N KOH, water and brine and then dried (MgSO4) and concentrated to give an oil. Flash chromatography on silica gel with 20% ethyl acetate in hexanes afforded a solid. Recrystallization from ether/hexanes yielded 32.0 g (53%) of pure product. mp 71°-73° C. Analysis calculated for C12H14O3 : C, 69.89; H, 6.84. Found: C, 69.85; H, 7.08.

Workup

  1. temperaturerefluxed over a Dean-Stark trap for 3 hours
  2. temperaturethe mixture again refluxed over the Dean-Stark trap for 18 hours
  3. concentrationThe mixture was concentrated
  4. additionpoured into water
  5. extractionextracted with ether
  6. extractionThe ether extract
  7. washwashed with 1N KOH, water and brine
  8. dry with materialdried (MgSO4)
  9. concentrationconcentrated
  10. customto give an oil
  11. customRecrystallization from ether/hexanes

Sources & evidence

ORD record
ord-75253980c3664a3986f3e06d038c425a
Source dataset
uspto-grants-1997_06
Patent number
US05641789

Reaction notes

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