Ethyl Acetate → Tert-butyl 6-bromo-2H-chromene-3-carboxylate

HRID 566013Notes

Reaction equation

HRID 566013 reaction equation
[Br:1][C:2]1[CH:9]=[C:6]([CH:7]=O)[C:5]([OH:10])=[CH:4][CH:3]=1.[C:11]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])(=[O:14])[CH:12]=[CH2:13].CC(C)([O-])C.[K+].C(OCC)(=O)C>C(O)(C)(C)C>[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:13][C:12]([C:11]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])=[CH:7][C:6]=2[CH:9]=1

Participants

6

Reactant 4

HCID 8857Ethyl AcetateHCID 15458tert-Butyl acrylateHCID 728635-BromosalicylaldehydeHCID 23665647Potassium tert-butoxide

Product 1

HCID 10566979Tert-butyl 6-bromo-2H-chromene-3-carboxylate

Reagents, catalysts & solvents 1

HCID 6386tert-ButanolSolvent

Procedure

To a solution of 5-bromosalicylaldehyde (10.0 g) and tert-butyl acrylate (17.5 ml) in tert-butanol (100 ml) was added potassium tert-butoxide (1.67 g) at room temperature, and the mixture was refluxed for 66 hours and cooled to room temperature. To the mixture was added ethyl acetate, and the mixture was washed with water, 1N sodium hydroxide and saturated sodium chloride solution, dried with magnesium sulfate and concentrated. The residue was separated and purified with column chromatography (ethyl acetate/hexane=1:19) to give tert-butyl 6-bromo-2H-1-benzopyran-3-carboxylate (10.86 g) as pale yellow crystals.

Workup

  1. temperaturethe mixture was refluxed for 66 hours
  2. washthe mixture was washed with water, 1N sodium hydroxide and saturated sodium chloride solution
  3. dry with materialdried with magnesium sulfate
  4. concentrationconcentrated
  5. customThe residue was separated
  6. custompurified with column chromatography (ethyl acetate/hexane=1:19)

Sources & evidence

ORD record
ord-afd69a20cc7945608347c9775d33c4d7
Source dataset
uspto-grants-2001_01
Patent number
US06172061B2

Reaction notes

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