Boron tribromide → 6-Chloro-5-hydroxy-1H-indole-2-carboxylic acid ethyl ester

HRID 1786474Notes

Reaction equation

HRID 1786474 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([O:15]C)=[C:10]([Cl:17])[CH:9]=2)=[O:5])[CH3:2].B(Br)(Br)Br>ClCCl>[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([OH:15])=[C:10]([Cl:17])[CH:9]=2)=[O:5])[CH3:2]

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 12200732ethyl 6-chloro-5-methoxy-1H-indole-2-carboxylate

Product 1

HCID 670179146-Chloro-5-hydroxy-1H-indole-2-carboxylic acid ethyl esterYield 74.6%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

To a cooled (−78° C.) solution of 6-chloro-5-methoxy-1H-indole-2-carboxylic acid ethyl ester (930 mg, 1.0 eq.) in dichloromethane (20 mL), was slowly added a 1M solution of boron tribromide in dichloromethane (7.33 mL, 2.0 eq.). The mixture was stirred at room temperature for 1 h, partitioned between ethyl acetate and ice water. The aqueous layer was extracted with ethyl acetate and the combined organic fractions were washed with 10% sodium bicarbonate solution and brine, dried over sodium sulfate, filtered, evaporated to dryness and purified on silica gel, eluting with a 4:1 to 3:1 gradient of cyclohexane/ethyl acetate, to yield 655 mg (74%) of the title compound as a light-brown solid.

Workup

  1. custompartitioned between ethyl acetate and ice water
  2. extractionThe aqueous layer was extracted with ethyl acetate
  3. washthe combined organic fractions were washed with 10% sodium bicarbonate solution and brine
  4. dry with materialdried over sodium sulfate
  5. filtrationfiltered
  6. customevaporated to dryness
  7. custompurified on silica gel
  8. washeluting with a 4:1 to 3:1 gradient of cyclohexane/ethyl acetate

Sources & evidence

ORD record
ord-2fa291c04abe4df0ac9941ccc6fda1bc
Source dataset
uspto-grants-2009_03
Patent number
US07507736B2

Reaction notes

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