Borane → Methyl 4-(4-bromo-2-formylbutyl)benzoate

HRID 2243289Notes

Reaction equation

HRID 2243289 reaction equation
[Br:1][CH2:2][CH2:3][CH:4]([CH2:8][C:9]1[CH:14]=[CH:13][C:12]([C:15]([O:17][CH3:18])=[O:16])=[CH:11][CH:10]=1)[C:5](O)=[O:6].B.[Cr](Cl)([O-])(=O)=O.[NH+]1C=CC=CC=1>C1COCC1.C(Cl)Cl>[Br:1][CH2:2][CH2:3][CH:4]([CH:5]=[O:6])[CH2:8][C:9]1[CH:14]=[CH:13][C:12]([C:15]([O:17][CH3:18])=[O:16])=[CH:11][CH:10]=1

Participants

6

Reactant 3

HCID 6331BoraneHCID 592108144-Bromo-2-[4-(methoxycarbonyl)benzyl]butanoic acidHCID 178418287HCID 178418287, compound

Product 1

HCID 17958613Methyl 4-(4-bromo-2-formylbutyl)benzoate

Reagents, catalysts & solvents 2

HCID 6344DichloromethaneSolventHCID 8028TetrahydrofuranSolvent2×

Procedure

At 0° C., 10.7 g (33.95 mmol) of 4-bromo-2-[4-(methoxycarbonyl)benzyl]butanoic acid from Ex. VII in 200 ml of THF are treated with 40.74 ml (40.74 mmol) of a 1M solution of borane in THF, and the mixture is stirred with warming to room temperature for 2 hours. Excess borane is destroyed by addition of water. The mixture is extracted with ether and the organic phase is then dried over magnesium sulfate and the solvent is distilled off under reduced pressure. 10.23 g (33.92 mmol) of the highly unstable methyl 4-[4-bromo-2-(hydroxymethyl)butyl]benzoate remain, and this residue is immediately dissolved in 100 ml of methylene chloride and added dropwise to a suspension of 10.98 g (50.92 mmol) of pyridinium chlorochromate in 200 ml of methylene chloride. After 3.5 hours, the solution is filtered through silica gel which is washed thoroughly with ether, and the solvent is distilled off. The crude product is purified by flash chromatography on silica gel (0.04-0.063 nm) using methylene chloride/methanol 3/1 as mobile phase.

Workup

  1. customAt 0° C.
  2. customExcess borane is destroyed by addition of water
  3. extractionThe mixture is extracted with ether
  4. dry with materialthe organic phase is then dried over magnesium sulfate
  5. distillationthe solvent is distilled off under reduced pressure
  6. dissolutionthis residue is immediately dissolved in 100 ml of methylene chloride
  7. filtrationthe solution is filtered through silica gel which
  8. washis washed thoroughly with ether
  9. distillationthe solvent is distilled off
  10. customThe crude product is purified by flash chromatography on silica gel (0.04-0.063 nm)

Sources & evidence

ORD record
ord-2d364452a3aa4524bf33bd77b5a6125f
Source dataset
uspto-grants-2010_03
Patent number
US07674825B2

Reaction notes

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