5-Bromosalicylaldehyde → 6-bromo-3-(5-bromo-2-thienyl)-4-hydroxy-2H-1-benzopyran-2-one

HRID 1636441Notes

Reaction equation

HRID 1636441 reaction equation
[Br:1][C:2]1[S:6][C:5]([C:7](=O)[C:8](OCC)=[O:9])=[CH:4][CH:3]=1.[Br:14][C:15]1[CH:16]=[CH:17][C:18]([OH:23])=[C:19]([CH:22]=1)[CH:20]=[O:21]>O.C(O)(=O)C.[Cl-].[Cl-].[Cl-].[Ti+3]>[Br:14][C:15]1[CH:16]=[CH:17][C:18]2[O:23][C:8](=[O:9])[C:7]([C:5]3[S:6][C:2]([Br:1])=[CH:3][CH:4]=3)=[C:20]([OH:21])[C:19]=2[CH:22]=1

Participants

6

Reactant 2

HCID 728635-BromosalicylaldehydeHCID 2736376Ethyl (5-bromothiophen-2-yl)(oxo)acetate

Product 1

HCID 547220506-bromo-3-(5-bromo-2-thienyl)-4-hydroxy-2H-1-benzopyran-2-one

Reagents, catalysts & solvents 3

HCID 10313229titanium(III) trichlorideCatalystHCID 176Acetic AcidSolventHCID 962WaterSolvent

Conditions

Temperature
4 °C

Procedure

A solution of titanium trichloride (7.71 g) in water (50 ml) was added to a solution of ethyl (5-bromo-2-thienyl)glyoxylate (5.0 g) and 5-bromo-2-hydroxybenzaldehyde (4.36 g) in dry acetic acid (50 ml) with stirring at 4° C. and the mixture was stirred for 11/2 hours. It was extracted with ethyl acetate and the extract was washed with water, brine, dried over magnesium sulfate and evaporated under reduced pressure. The residue was dissolved in toluene and p-toluenesulfonic acid (2.5 g) was added and the mixture heated under reflux for 21/2 hours. It was allowed to stand at room temperature overnight and evaporated under reduced pressure. The residue was purified by silica gel column chromatography to give 6-bromo-3-(5-bromo-2-thienyl)-4-hydroxy-2H-1-benzopyran-2-one, m.p. 234-6° C. (compound 27)

Workup

  1. stirringthe mixture was stirred for 11/2 hours
  2. extractionIt was extracted with ethyl acetate
  3. washthe extract was washed with water, brine
  4. dry with materialdried over magnesium sulfate
  5. customevaporated under reduced pressure
  6. dissolutionThe residue was dissolved in toluene
  7. additionp-toluenesulfonic acid (2.5 g) was added
  8. temperaturethe mixture heated
  9. temperatureunder reflux for 21/2 hours
  10. customevaporated under reduced pressure
  11. customThe residue was purified by silica gel column chromatography

Sources & evidence

ORD record
ord-2769afbef0c34fecb25ee535d7afd5f9
Source dataset
uspto-grants-2000_03
Patent number
US06034121

Reaction notes

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