Acetic Acid → 2-Chloro-5-fluoropyridine-3-carboxamide

Participants

Reaction Steps

A suspension of 21.9 g (335.35 mmol) of zinc in methanol (207 ml) was admixed at RT with 44 g (210.58 mmol) of 2,6-dichloro-5-fluoronicotinamide. Acetic acid (18.5 ml) was then added, and the mixture was heated to reflux while stirring for 24 h. The contents of the flask were then decanted off from the zinc, and ethyl acetate (414 ml) and saturated aqueous sodium hydrogencarbonate solution (414 ml) were added, followed by vigorous stirring. Subsequently, the reaction mixture was filtered with suction through kieselguhr and washed through three times with ethyl acetate (517 ml each time). The organic phase was removed and the aqueous phase was washed with ethyl acetate (258 ml). The combined organic phases were washed once with saturated aqueous sodium hydrogencarbonate solution (414 ml), dried and concentrated under reduced pressure. Dichloromethane (388 ml) was added to the crystals thus obtained, and the mixture was stirred for 20 min. The mixture was once more filtered with suction, washed through with diethyl ether and sucked dry.

Provenance & Evidence