Indium(III)-Mediated Synthesis of Quinoline-4-carboxylic Acid Derivatives

Significance

Readily available 2-substituted acrylates or acrylamides undergo Povarov-like cyclization with N-arylimines to produce quinoline-4-carboxylic acid derivatives employing InCl₃ under microwave activation and mild conditions. The scope of the method falls short in that reactions of compounds bearing electron-withdrawing groups in 2′- and 3′-position fail to give the expected products. ¹³C NMR spectroscopic as well as theoretical studies suggest that InCl₃ facilitates the cyclization by acting as a chelating reagent between the two reactants.