Phosphoric Acid → 2-Formylisonicotinonitrile

Participants

Reaction Steps

To 4-cyano-2-hydroxymethylpyridine (1.1 g, 8.2 mmol) from stage A in dry DMSO (18 mL) was added N,N-dicyclohexylcarbodiimide (5.08 g, 24.6 mmol) and phosphoric acid (0.4 g, 4.1 mmol). The mixture was stirred overnight at room temperature. The solid was removed by filtration and washed with ether and water. The filtrate and washings were combined, and the organic layer separated. The aqueous layer was further extracted 4 times with ether, the organics combined, dried over magnesium sulphate and evaporated. The residue was purified by SPE silica column chromatography, eluting with dichloromethane, then chloroform, then diethyl ether. Evaporation of the appropriate fractions afforded 4-cyanopyridine-2-carboxaldehyde as a solid.

Provenance & Evidence