Methanol → 5,6-Dimethoxy-3h-imidazo[4,5-b]pyridine

HRID 2391730Notes

Reaction equation

HRID 2391730 reaction equation
[N:1]([C:4]1[C:9]([N+:10]([O-])=O)=[CH:8][C:7]([O:13][CH3:14])=[C:6]([O:15][CH3:16])[N:5]=1)=[N+]=[N-].[CH3:17]O>[Pd]>[CH3:16][O:15][C:6]1[N:5]=[C:4]2[N:1]=[CH:17][NH:10][C:9]2=[CH:8][C:7]=1[O:13][CH3:14]

Participants

4

Reactant 2

HCID 887MethanolHCID 866471232-Azido-5,6-dimethoxy-3-nitropyridine

Product 1

HCID 687649905,6-Dimethoxy-3h-imidazo[4,5-b]pyridine

Reagents, catalysts & solvents 1

HCID 23938PalladiumCatalyst

Procedure

A suspension of 11.6 g of 2-azido-5,6-dimethoxy-3-nitropyridine (example E5) in 600 ml methanol was treated with 1.7 g Pd/C (10% Pd) and hydrogenated for 16 h under atmospheric pressure. The reaction mixture was rapidly filtered through a plug of CELITE® (diatomaceous earth), the filtrate was concentrated under vacuum and the residue was refluxed in 100 ml of formic acid for 18 h. The formic acid was removed under vacuum and the resulting residue was dried under vacuum at 100-110° C. to yield crude 5,6-dimethoxy-1H-imidazo[4,5-b]pyridine (as formic acid salt and/or as free base) that was used for the following step without further purification (MS (MH+ found)=180.2).

Workup

  1. filtrationThe reaction mixture was rapidly filtered through a plug of CELITE® (diatomaceous earth)
  2. concentrationthe filtrate was concentrated under vacuum
  3. temperaturethe residue was refluxed in 100 ml of formic acid for 18 h
  4. customThe formic acid was removed under vacuum
  5. customthe resulting residue was dried under vacuum at 100-110° C.

Sources & evidence

ORD record
ord-e870c11e823a4d168828ef7edcb30ee3
Source dataset
uspto-grants-2012_09
Patent number
US08273890B2

Reaction notes

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