Nickel Chloride Hexahydrate‐Catalyzed Regioselective Synthesis of Quinolines and Bis‐Quinolines Under Aerial Oxidation

Two‐component synthesis of quinoline and bis‐quinoline derivatives using nickel chloride hexahydrate as a catalyst via Michael addition followed by aldol condensation from α,β ‐unsaturated ketone and o ‐aminobenzyl alcohol. This protocol enables access to phenyl(2‐phenylquinolin‐3‐yl)methanone and bis(2‐phenylquinolin‐3‐yl)methanone derivatives in good to excellent yields using toluene solvent at 100 °C temperature in open‐air condition. Nickel chloride hexahydrate has been utilized in this study to oxidize benzyl alcohols to intermediate benzaldehydes. Green chemistry metrics of the reaction explain the dominance of the methodology. The structural characterization of the compounds was confirmed by 1 H, 13 C, Infrared (IR), UV–vis spectroscopy, and high resolution mass spectrometry (HRMS) analysis.