The reaction between β-keto esters and arylamines in the presence of polyphosphoric acid. I. Ethyl benzoylacetate and arylamines

2-Phenyl-4-hydroxyquinolines may be obtained directly from ethyl benzoylacetate and arylamines using polyphosphoric acid. Under certain conditions a mixture of benzoylacetanilide and β-arylaminocinnamate (or anil) is obtained. It is also shown that while the β-arylaminocinnamates give the expected 4-hydroxyquinolines on cyclization when heated with polyphosphoric acid, the benzoylacetanilides tend to give mixtures of the isomeric 2-hydroxy- and 4-hydroxyquinolines.