Novel Synthetic and Mechanistic Approach of TFA Catalysed Friedländer Synthesis of 2‐Acylquinolines from Symmetrical and Unsymmetrical 1,2‐Diketones with o‐Aminoarylketones

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AbstractIn focussing on the reaction mechanism of Friedländer synthesis in the presence of acid catalysts, novel regioselective synthesis of 2‐acetylquinolines from reacting a symmetrical 1,2‐diketone, butan‐2,3‐dione with o‐aminoarylketones was reported. Similar condensation of o‐aminoarylketones with unsymmetrical 1,2‐diketone, pentan‐2,3‐dione leads to the formation of 2‐propanoylquinoline. The proposed reaction mechanism is scrutinized through density functional calculations at B3LYP/6‐311G (d,p) and M06‐2X/6‐311G (d,p) level of theory and also all the relative energy barriers and activation energies of the reaction steps are found to be minimum at above level of theory. Results from theoretical study have further strengthened by FT‐IR, FT‐NMR chemical shifts and structural parameters which were achieved with the same level of theory and the corresponding results were substantiate with experimental observations.