3-Methyl-but-2-enoic acid 4-bromo-phenyl ester → 2H-1-Benzopyran-2-one, 6-bromo-3,4-dihydro-4,4-dimethyl-

HRID 841593Notes

Reaction equation

HRID 841593 reaction equation
[Br:1][C:2]1[CH:7]=[CH:6][C:5]([O:8][C:9](=[O:14])[CH:10]=[C:11]([CH3:13])[CH3:12])=[CH:4][CH:3]=1.[Cl-].[Al+3].[Cl-].[Cl-]>ClCCl>[Br:1][C:2]1[CH:3]=[C:4]2[C:5](=[CH:6][CH:7]=1)[O:8][C:9](=[O:14])[CH2:10][C:11]2([CH3:12])[CH3:13]

Participants

4

Reactant 2

HCID 7337973-Methyl-but-2-enoic acid 4-bromo-phenyl esterHCID 6451240Aluminum(III) Chloride

Product 1

HCID 225689232H-1-Benzopyran-2-one, 6-bromo-3,4-dihydro-4,4-dimethyl-Yield 59.7%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of 3-methyl-but-2-enoic acid 4-bromo-phenyl ester (7 g, 27.6 mmol) in anhydrous dichloromethane (200 mL) was cooled (ice bath) and treated with aluminum chloride (6.6 g, 49.6 mmol) and the reaction mixture was stirred overnight at ambient temperature. The reaction mixture was quenched with saturated aqueous sodium bicarbonate solution and extracted with diethyl ether (×2). The combined organic extract was washed with brine (×1), dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to afford an oil which was purified by flash column chromatography over silica gel (230-400 mesh) using 2.5% ethyl acetate in hexane as the eluent to afford the title compound (4.2 g, 57%).

Workup

  1. customThe reaction mixture was quenched with saturated aqueous sodium bicarbonate solution
  2. extractionextracted with diethyl ether (×2)
  3. extractionThe combined organic extract
  4. washwas washed with brine (×1)
  5. dry with materialdried over anhydrous sodium sulfate
  6. filtrationfiltered
  7. customevaporated in vacuo
  8. customto afford an oil which
  9. customwas purified by flash column chromatography over silica gel (230-400 mesh)

Sources & evidence

ORD record
ord-2eada4d6cde34409afa255b69222f611
Source dataset
uspto-grants-2002_04
Patent number
US06369261B1

Reaction notes

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