The use of polyphosphoric ester and polyphosphoric acid in the synthesis of 1,4-dihydro-4-oxoquinolines

Abstract

The synthesis of 1-alkyl-1,4-dihydro-4-oxoquinolines by the cyclization of derivatives of 2-(N-alkylanilino)acrylic acid in the presence of polyphosphoric acid or ester has been investigated. The results indicate that polyphosphoric ester is a more efficient reagent for the cyclization of 2-(N-alkylanilino)acrylic acid derivatives than polyphosphoric acid and also has advantages over the thermal cyclization.