Boron tribromide → (6-Hydroxy-benzo[b]thiophen-3-yl)-acetic acid ethyl ester

HRID 2261833Notes

Reaction equation

HRID 2261833 reaction equation
[CH2:1]([O:3][C:4](=[O:17])[CH2:5][C:6]1[C:7]2[CH:14]=[CH:13][C:12]([O:15]C)=[CH:11][C:8]=2[S:9][CH:10]=1)[CH3:2].B(Br)(Br)Br>ClCCl>[CH2:1]([O:3][C:4](=[O:17])[CH2:5][C:6]1[C:7]2[CH:14]=[CH:13][C:12]([OH:15])=[CH:11][C:8]=2[S:9][CH:10]=1)[CH3:2]

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 21816275Ethyl 2-(6-methoxybenzo[b]thiophen-3-yl)acetate

Product 1

HCID 57431998(6-Hydroxy-benzo[b]thiophen-3-yl)-acetic acid ethyl esterYield 93.2%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of (6-methoxy-benzo[b]thiophen-3-yl)-acetic acid ethyl ester (3.81 g, 15.22 mmol) in dichloromethane (50 mL) at −78° C. is added boron tribromide (38.1 mL, 38.1 mmol) dropwise. The mixture is stirred and allowed to warm to room temperature overnight. The mixture is cooled to 0° C. and quenched with water (100 mL). The organic layer is separated, and the aqueous layer is extracted with EtOAc (50 mL). The combined organic layers are dried over Na2SO4, filtered, and concentrated. The crude product is purified by flash chromatography eluting with 30-40% EtOAc/Hexanes. The appropriate fractions are pooled and concentrated under reduced pressure. The material is dried in vacuo to afford (6-hydroxy-benzo[b]thiophen-3-yl)-acetic acid ethyl ester (3.35 g, 93%). ES/MS m/e 237.0 (M+1); 235.0 (M−1).

Workup

  1. temperatureThe mixture is cooled to 0° C.
  2. customquenched with water (100 mL)
  3. customThe organic layer is separated
  4. extractionthe aqueous layer is extracted with EtOAc (50 mL)
  5. dry with materialThe combined organic layers are dried over Na2SO4
  6. filtrationfiltered
  7. concentrationconcentrated
  8. customThe crude product is purified by flash chromatography
  9. washeluting with 30-40% EtOAc/Hexanes
  10. concentrationconcentrated under reduced pressure
  11. customThe material is dried in vacuo

Sources & evidence

ORD record
ord-f9993708a9044c78beeae11fcebd02ed
Source dataset
uspto-grants-2010_12
Patent number
US07846960B2

Reaction notes

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