Skraup-Doebner-Von Miller quinoline synthesis revisited: reversal of the regiochemistry for gamma-aryl-beta,gamma-unsaturated alpha-ketoesters

J Org Chem. 2006 Aug 18;71(17):6592-5. doi: 10.1021/jo060290n.

Abstract

A reversal of the standard regiochemistry of the Skraup-Doebner-Von Miller quinoline synthesis was observed when anilines were condensed with gamma-aryl-beta,gamma-unsaturated alpha-ketoesters in refluxing TFA. The reaction is proposed to involve 1,2-addition of the anilines to gamma-aryl-beta,gamma-unsaturated alpha-ketoesters to form Schiff's base adducts, followed by cyclization and oxidation. The products were unambiguously shown to the 2-carboxy-4-arylquinolines by spectroscopy and X-ray crystallographic analysis.