Ethanol → 3-(1H-Indol-3-yl)prop-2-enal

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Reaction Steps

To a solution of 10.0 g of 2-(pyridin-3-yl)aniline (58.7 mmol) in 100 mL ethanol is slowly added 6.2 mL of cyanogen bromide (12.4 g, 118 mmol). The reaction is heated to reflux for 1 hour, monitoring by TLC (silica, hexanes:ethyl acetate 1:1) for formation of the Zincke salt. The reaction is then quenched via addition of 50 mL saturated NH4Cl, and extracted with 3×50 mL dichloromethane. The combined organic layers are washed 3×100 mL saturated NH4Cl, followed by drying over anhydrous Na2SO4 and removal of the solvent. The crude residue is further purified via column chromatography over silica, using a hexanes-ethyl acetate gradient.

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