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

HRID 1193619Notes

Reaction equation

HRID 1193619 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-DimethylchromanHCID 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 7.94 g (48.9425 mmol) of 4,4-dimethylchroman (from Example 8) 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° C.; 0.15 mm) to give the title compound as a colorless oil. PMR (CDCl): δ 1.40 (6H), 1.95-2.00 (2 H, 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° C.; 0.15 mm)

Sources & evidence

ORD record
ord-bb37a8bdc9514e619f0df3ab802e444b
Source dataset
uspto-grants-1989_03
Patent number
US04810804

Reaction notes

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