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

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Reaction Steps

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).

Provenance & Evidence