In a previous communication,'comparison of the ultraviolet absorption spectra of several pyridopyrimidones led to the conclusion that benzoylacetamidopyridine (I) does not cyclize in concentrated sulfuric acid to give 4-phenyl-2H-pyrido [1, 2-a] pyrimidin-2-one (11), but instead rearranges and yields 2-phenyl-4H-pyrido [lI2-a] pyrimidin-4-one (111). A new reaction of some compounds of this series has now been discovered which provides ...