Acetyl chloride → 2,2,4,4,7-Pentamethyl-6-acetylchroman

HRID 1085026Notes

Reaction equation

HRID 1085026 reaction equation
[CH3:1][C:2]1([CH3:15])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][C:6]([CH3:14])=[CH:7][CH:8]=2)[O:3]1.[C:16](Cl)(=[O:18])[CH3:17].[Cl-].[Al+3].[Cl-].[Cl-]>[N+](C)([O-])=O.CCOCC.O>[CH3:1][C:2]1([CH3:15])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][C:6]([CH3:14])=[C:7]([C:16](=[O:18])[CH3:17])[CH:8]=2)[O:3]1

Participants

7

Reactant 3

HCID 6367Acetyl chlorideHCID 6451240Aluminum(III) ChlorideHCID 156611242,2,4,4,7-Pentamethyl-chroman2×

Product 1

HCID 156611372,2,4,4,7-Pentamethyl-6-acetylchroman

Reagents, catalysts & solvents 3

HCID 962WaterSolventHCID 3283Diethyl EtherSolventHCID 6375NitromethaneSolvent

Procedure

To an ice-bath cooled solution of 1.96 g (9.6 mmol) of 2,2,4,4,7-pentamethyl-chroman (Compound 52) in 30 ml of nitromethane was added under argon 1.059 g (13.5 mmol) of acetyl chloride followed by 1.9 g (14.3 mmol) of aluminum chloride. The reaction mixture was stirred at room temperature for 14 h and then cooled in an ice-bath and treated with 25 ml of conc. HC1. The mixture was warmed to room temperature and diluted with ether and water. The organic layer was separated and the aqueous layer extracted with ether. The organic extracts were combined and washed successively with water, saturated NaHCO3 solution, water again, and saturated NaCl solution, and then dried (MgSO4). The solvent was removed in vacuo and the residue was purified by flash chromatography (silica; 5% ethyl acetate in hexanes) to give the title compound as a pale yellow oil. PMR (CDCl3): 1.36 (6H, s), 1.37 (6H, s), 1.86 (2H, s), 2.49 (3H, s), 2.56 (3H, s), 6.65 (1H, s), 7.74 (1H, s).

Workup

  1. temperaturecooled in an ice-bath
  2. additiontreated with 25 ml of conc. HC1
  3. temperatureThe mixture was warmed to room temperature
  4. customThe organic layer was separated
  5. extractionthe aqueous layer extracted with ether
  6. washwashed successively with water, saturated NaHCO3 solution, water again
  7. dry with materialsaturated NaCl solution, and then dried (MgSO4)
  8. customThe solvent was removed in vacuo
  9. customthe residue was purified by flash chromatography (silica; 5% ethyl acetate in hexanes)

Sources & evidence

ORD record
ord-6897bd16a8c44a5ba50691a42207a71e
Source dataset
uspto-grants-1991_04
Patent number
US05006550

Reaction notes

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