Acetone → 6-Benzyloxy-2,2-dimethylchroman-4-one

HRID 1684621Notes

Reaction equation

HRID 1684621 reaction equation
[CH3:1][C:2]([C:4]1[CH:9]=[C:8]([O:10][CH2:11][C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)[CH:7]=[CH:6][C:5]=1[OH:18])=[O:3].[CH3:19][C:20]([CH3:22])=O.N1CCCC1.C(OCC)(=O)C>C1(C)C=CC=CC=1>[CH2:11]([O:10][C:8]1[CH:9]=[C:4]2[C:5](=[CH:6][CH:7]=1)[O:18][C:20]([CH3:22])([CH3:19])[CH2:1][C:2]2=[O:3])[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1

Participants

6

Reactant 4

HCID 180Acetone2×HCID 8857Ethyl AcetateHCID 31268Pyrrolidine2×HCID 128709281-[5-(Benzyloxy)-2-hydroxyphenyl]ethan-1-one

Product 1

HCID 117809926-Benzyloxy-2,2-dimethylchroman-4-oneYield 47%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

A mixture of 25.0 g (0.103 mole) 2-hydroxy-5-benzyloxyacetophenone, 8 mL (6.0 g, 0.130 mole) acetone and 4 mL (3.7 g, 0.052 mole) pyrrolidine in 100 mL toluene was stirred at room temperature for 4 hours, then refluxed over a Dean-Stark trap for 3 hours. An additional 8 mL (6.0 g, 0.130 mole) acetone and 4 mL (3.7 g, 0.052 mole) pyrrolidine was added and the mixture refluxed for 18 hours. The mixture was concentrated, poured into water, basified to pH 8 with ammonium hydroxide, then extracted with ether. The ether extract was washed successively with 1N KOH, 1N HCl, water and brine, then dried (MgSO4) and concentrated to give an oil. Flash chromatography on silica gel eluting with 20% ethyl acetate in hexanes afforded a solid. Recrystallization from ethyl acetate in hexanes afforded a solid. Recrystallization from ethyl acetate in hexanes yielded the title product as a solid 13.6 g (47%), mp 105°-107° C. NMR (CDCl3): δ1.4 (s, 6H); 2.7 (s, 2H); 5.1 (s, 2H).

Workup

  1. temperaturerefluxed over a Dean-Stark trap for 3 hours
  2. temperaturethe mixture refluxed for 18 hours
  3. concentrationThe mixture was concentrated
  4. additionpoured into water
  5. extractionextracted with ether
  6. extractionThe ether extract
  7. washwas washed successively with 1N KOH, 1N HCl, water and brine
  8. dry with materialdried (MgSO4)
  9. concentrationconcentrated
  10. customto give an oil
  11. customRecrystallization from ethyl acetate in hexanes
  12. customafforded a solid
  13. customRecrystallization from ethyl acetate in hexanes

Sources & evidence

ORD record
ord-01370a3167c246b28638b7b956ad58a5
Source dataset
uspto-grants-1997_06
Patent number
US05641789

Reaction notes

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