Boron tribromide → 2-methyl-1H-indol-5-ol

HRID 129380

Reaction equation

HRID 129380 reaction equation
C[O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7]([CH3:12])=[CH:6]2.B(Br)(Br)Br.O.C(Cl)(Cl)Cl>C(Cl)Cl>[OH:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7]([CH3:12])=[CH:6]2

Participants

5

Reactant 3

HCID 25134Boron tribromideHCID 706425-Methoxy-2-methylindoleHCID 22418719Chloroform water

Product 1

HCID 833362-methyl-1H-indol-5-olYield 67.5%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a -65° C. solution of 8.6 g (53.4 m mol) 5-methoxy-2-methyl indole in 110 mL of CH2Cl2 was added dropwise 30.4 g (117 m mol) of boron tribromide. The reaction was allowed to warm to room temperature and stirred for 30 minutes. After cooling the mixture to 5° C., 200 mL of 50% water/chloroform was cautiously added. The aqueous layer was separated and the pH adjusted to 5.8 with aqueous sodium hydroxide. Extracting the mixture twice with 100 mL of ethyl acetate, followed by drying (Na2SO4), filtering and concentrating provided 5.3 g of the product as a yellow solid, mp 124°-126° C. 1H NMR (60 MHz, 20% DMSO d6 /CDCl3) δ 8.05 (s, 1H, NH), 7.05 (d, J=8 Hz, 1H), 6.80 (d, J=2 Hz, 1H), 6.55 (dd, J=2, 8 Hz, 1H), 5.90 (broad s, 1H, indole CH), 2.40 (s, 3H).

Workup

  1. temperatureAfter cooling the mixture to 5° C.
  2. customThe aqueous layer was separated
  3. extractionExtracting the mixture twice with 100 mL of ethyl acetate
  4. dry with materialby drying (Na2SO4)
  5. filtrationfiltering
  6. concentrationconcentrating

Sources & evidence

ORD record
ord-9712532fcbc34ab18b8806c8f119b740
Source dataset
uspto-grants-1995_11
Patent number
US05468641

Linked notes

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