Boron tribromide → 6-Bromo-1H-indazol-5-ol

HRID 1661970Notes

Reaction equation

HRID 1661970 reaction equation
[Br:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[N:7][NH:8]2)=[CH:4][C:3]=1[O:11]C.B(Br)(Br)Br>C(Cl)Cl>[Br:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[N:7][NH:8]2)=[CH:4][C:3]=1[OH:11]

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 569716546-Bromo-5-methoxy-1H-indazole

Product 1

HCID 591599466-Bromo-1H-indazol-5-olYield 75.3%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

To a solution of 6-bromo-5-methoxy-1H-indazole (60 g, 0.265 mol) in DCM (1300 mL) is added a solution of BBr3 (105 g, 0.42 mol) in DCM (200 mL) at 0° C. The reaction mixture is warmed to RT and stirred overnight. Then the reaction solution is quenched with MeOH at 0° C. The solvent is removed in vacuo and the residue is neutralized with NaHCO3 solid. The mixture is partitioned by water (1500 mL) and EtOAc (1500 mL). The aqueous layer is extracted with EtOAc (1500 mL) two times. The combined organic layers are dried and concentrated to give crude product, which is purified by silica gel column chromatography (PE:THF=2:1) to give the desired product (42.5 g, 75% yield). MS (m/z): 215.0 (M+H).

Workup

  1. customThen the reaction solution is quenched with MeOH at 0° C
  2. customThe solvent is removed in vacuo
  3. customThe mixture is partitioned by water (1500 mL) and EtOAc (1500 mL)
  4. extractionThe aqueous layer is extracted with EtOAc (1500 mL) two times
  5. customThe combined organic layers are dried
  6. concentrationconcentrated
  7. customto give crude product, which
  8. customis purified by silica gel column chromatography (PE:THF=2:1)

Sources & evidence

ORD record
ord-b8748961445b471b934da2d17d66348b
Source dataset
uspto-grants-2011_10
Patent number
US08030302B2

Reaction notes

Loading…