An Unexpected Result in the Condensation of 2-Amino-6-bromopyridine with Ethyl 4-Chloroacetoacetate: Four Dihalo-substituted Pyrido[1,2-a]pyrimidin-4-ones as Reaction Products

摘要

We report here the condensation of 2-amino-6-bromopyridine with ethyl 4-chloroacetoacetate in polyphosphoric acid. In this reaction, a mixture of the four possible dihalo-4H-pyrido[1,2-a]pyrimidin-4-ones 1-4 was obtained.