Synthesis of Quinolines and Pyrido[3,2‑g or 2,3‑g]quinolines Catalyzed by Heterogeneous Propylphosphonium Tetrachloroindate Ionic Liquid

This report explains an efficient method for synthesis of an array of quinolines via the reaction of 2-aminoaryl ketones with terminal and internal alkynes in the presence of propylphosphonium tetrachloroindate ionic liquid supported on nanosilica (PPInCl-nSiO₂) as a heterogeneous and reusable catalyst under solvent-free conditions. Inspired by this catalytic system, the first easy one-step synthesis of symmetric and unsymmetric pyrido­[3,2-g or 2,3-g]­quinolines was investigated through the reaction of diaroylphenylenediamines with one alkyne or two different alkynes.