Acetyl chloride → 1-(2,2,4,4-Tetramethyl-3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

HRID 862262Notes

Reaction equation

HRID 862262 reaction equation
[CH3:1][C:2]1([CH3:14])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[O:3]1.[C:15](Cl)(=[O:17])[CH3:16].[Cl-].[Al+3].[Cl-].[Cl-]>[N+](C)([O-])=O>[CH3:1][C:2]1([CH3:14])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][CH:6]=[C:7]([C:15](=[O:17])[CH3:16])[CH:8]=2)[O:3]1

Participants

5

Reactant 3

HCID 6367Acetyl chlorideHCID 6451240Aluminum(III) ChlorideHCID 156611252,2,4,4-Tetramethylchroman2×

Product 1

HCID 156611361-(2,2,4,4-Tetramethyl-3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

Reagents, catalysts & solvents 1

HCID 6375NitromethaneSolvent

Procedure

To an ice bath cooled solution of 2 g (10.53 mmol) of 2,2,4,4-tetramethylchroman (Compound 84) in 25 ml of nitromethane was added, under nitrogen, 941 mg (11.99 mmol) of acetyl chloride followed by 1.59 g (11.92) mmol) of aluminum chloride. The cooling bath was then removed and the mixture stirred at room temperature for 16 h. The mixture was then cooled again in an ice bath and treated with 25 ml of conc. HCl. The mixture was then filtered and the residue washed with methylene chloride. The filtrate was concentrated in vacuo and the resultant residue was purified by flash chromatography (silica; 10% ethyl acetate in hexanes) to give the title compound as a yellow oil. PMR (CDCl3): & 1.38 (6H, s), 1.39 (6H, s), 1.87 (2H, s), 2.56 (3H, s), 6.83 (1H, d, J~8.7 Hz), 7.71 (1H, dd, J~8.7 Hz, 2.1 Hz), 7.98 (1H, d, J~2.1 Hz). MS exact mass, m/e 232.1468 (calcd. for C13H20O2, 232.1464).

Workup

  1. additionwas added, under nitrogen
  2. customThe cooling bath was then removed
  3. temperatureThe mixture was then cooled again in an ice bath
  4. additiontreated with 25 ml of conc. HCl
  5. filtrationThe mixture was then filtered
  6. washthe residue washed with methylene chloride
  7. concentrationThe filtrate was concentrated in vacuo
  8. customthe resultant residue was purified by flash chromatography (silica; 10% ethyl acetate in hexanes)

Sources & evidence

ORD record
ord-d0756d3683b84985ba1f8944126da4d3
Source dataset
uspto-grants-1998_02
Patent number
US05717094

Reaction notes

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