Diethyl (ethoxymethylene)malonate → Ethyl 9-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylate

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Reaction Steps

Diethylbenzene Process: A mixture of 66.0 g of 2-amino-3-pyridinol, 220.0 g of diethyl ethoxymethylenemalonate, and 1.0 liter of diethylbenzene was heated so that the internal temperature reached 140° in 1 hour, was kept for 1 hour at 140°, then heated so that the temperature rose to 180° in 1 hour, and then kept 1 hour at 180°. During this entire heating period, 50 ml. of distillate was collected. The solution was allowed to cool spontaneously, was cooled at 0°, filtered, and the solid washed with diisopropyl ether to give 130.0 g of product, after drying at 56° in vacuo. The m.p. was 175°-177° and a mixture m.p. with the product isolated in (a) above was 175°-177°. The ir and pmr spectra of the two samples were superimposable. The yield was 93%.

Provenance & Evidence