Synthesis and cytotoxic activity of substituted 2-phenyl-3-hydroxy-4(1 H)-quinolinones-7-carboxylic acids and their phenacyl esters

The preparation of 3-hydroxy-2-phenyl-4(1 H)-quinolinones substituted in position 7 with a carboxyl group is described. The synthesis is based on the reaction of 2-aminoterephthalic acid with substituted α-bromoacetophenones and subsequent cyclization of the resulting bisphenacylesters in polyphosphoric acid. The reaction affords a mixture of substituted 3-hydroxy-2-phenyl-4(1 H)-quinolinones 7-carboxylic acids as well as their phenacylesters. All quinolinones prepared (acids and phenacylesters) were tested for cytotoxic activity in vitro against five cancer cell lines and the results and a tentative structure–activity relationship are reported.