2-Amino-3-Hydroxypyridine → Oxazolo(4,5-b)pyridin-2(3H)-one

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Reaction Steps

5.5 g (0.05 mol) of 2-amino-3-hydroxypyridine are introduced into a three-necked flask and the system is placed under argon. 100 ml of anhydrous tetrahydrofuran (THF) are added. 12.15 g (0.075 mol) of 1,1'-carbonyl-diimidazole are then introduced. The mixture is heated to reflux for 5 hours (under argon). The THF is then evaporated off. The residue is taken up with dichloromethane. Washings of the organic phase are performed with NaOH (5%) solution (6×150 ml); the cyclized product passes into the aqueous phase and precipitates at a pH in the region of 5 (by adding 2 N hydrochloric acid solution). The product is filtered off and stored in a desiccator.

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