Ethanol → Ethyl 4-hydroxy-6-methoxy-1,5-naphthyridine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of 2-[(6-methoxy-pyridin-3-ylamino)-methylene]-malonic acid diethyl ester (260.0 g, 1.365 mol, 1.0 eq) in diphenyl ether (500 mL) is heated to reflux. While the ethanol formed is removed by azeotropic distillation the reflux temperature reached 245° C. The reaction mixture is kept at 245° C. for 3 hours, then it is cooled to 28° C., a brown solid precipitated and is collected by filtration and washed with hexane (500 mL). The solid is dried under vacuum to afford 6-methoxy-4-oxo-1,4-dihydro-[1,5]naphthyridine-3-carboxylic acid ethyl ester as a brown powder (74.2 g, 32% yield).

Provenance & Evidence