N-Hydroxyisonicotinimidamide → 4-[5-(3,4-Bis-benzyloxy-5-nitro-phenyl)-[1,2,4]oxadiazol-3-yl]-pyridine

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Reaction Steps

To a stirred solution of 3,4-dibenzyloxy-5-nitrobenzoic acid (0.5 g, 1.32 mmol) in dimethylformamide (5 mL) at room temperature was added 1,1-carbonyldiimidazole (0.246 g, 1.52 mmol) in one portion. After stirring for one hour, N′-hydroxypyridine-4-carboximidamide (0.208 g, 1.52 mmol) was added in one portion and the resulting mixture was stirred at room temperature overnight. The mixture was then stirred at 110° C. for three hours and then allowed to cool to room temperature. The mixture was poured onto ice-water (100 mL) and extracted with 20% isopropanol/dichloromethane. The organic extracts were washed with water and brine, then dried (Na2SO4), filtered and evaporated to leave a solid residue that was recrystallised from ethanol. 4-[5-(3,4-Bis-benzyloxy-5-nitro-phenyl)-[1,2,4]oxadiazol-3-yl]-pyridine was obtained as a beige solid (0.395 g, 62%).

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