Hydrochloric Acid → 1-(4,4-Dimethyl-3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

HRID 1085018Notes

Reaction equation

HRID 1085018 reaction equation
[CH3:1][C:2]1([CH3:12])[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[O:5][CH2:4][CH2:3]1.[C:13](Cl)(=[O:15])[CH3:14].[Cl-].[Al+3].[Cl-].[Cl-].Cl>[N+](C)([O-])=O.CCOCC>[CH3:1][C:2]1([CH3:12])[C:11]2[C:6](=[CH:7][CH:8]=[C:9]([C:13](=[O:15])[CH3:14])[CH:10]=2)[O:5][CH2:4][CH2:3]1

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 6367Acetyl chlorideHCID 3167634,4-Dimethylchroman2×HCID 6451240Aluminum(III) Chloride

Product 1

HCID 134781601-(4,4-Dimethyl-3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 6375NitromethaneSolvent

Procedure

To a stirred solution of 7.94g (48.9425 mmol) of 4,4-dimethylchroman (Compound 37) in 70 ml of nitromethane was added under argon 4.0 g (50.96 mmol) of acetyl chloride followed by 6.8 g (51 mmol) of aluminum chloride. This was stirred at room temperature for 5.5 hours and then cooled in an ice bath and treated slowly with 70 ml of 6N hydrogen chloride. The resultant mixture was stirred at room temperature for 10 minutes and then treated with 100 ml ether and the organic layer separated. The organic layer was washed with water saturated NaHCO3 and saturated NaCl solutions and dried (MgSO4). Solvent was removed in vacuo and the residue purified by flash chromatography (silica; 10% ethyl acetate in hexanes). This was followed by kugelrohr distillation (95-100 degrees C.; 0.15 mm) to give the title compound as a colorless oil. PMR (CDCl3): & 1.40 (6H), 1.95-2.00 (2H, m), 2.58 (3H), 4.25-4.30 (2H, m), 6.83 (1H, d, J~8.0 Hz), 7.62 (1H, dd, J~8.0 Hz, 1.5 Hz), 8.00 (1H, d, J~1.5 Hz).

Workup

  1. temperaturecooled in an ice bath
  2. customthe organic layer separated
  3. washThe organic layer was washed with water saturated NaHCO3 and saturated NaCl solutions
  4. dry with materialdried (MgSO4)
  5. customSolvent was removed in vacuo
  6. customthe residue purified by flash chromatography (silica; 10% ethyl acetate in hexanes)
  7. distillationThis was followed by kugelrohr distillation (95-100 degrees C.; 0.15 mm)

Sources & evidence

ORD record
ord-6059f1497d9446c1acc8adb44b34a766
Source dataset
uspto-grants-1991_04
Patent number
US05006550

Reaction notes

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