Base-Mediated Regioselective Synthesis of Pyrrolo[3,4-b]quinolin-1-one and Benzo[b][1,6]Naphthyridin-1(2H)-One Derivatives from o-Alkynyl Quinoline-3-carbonitriles and Their Photophysical Properties

A (KOBu)-Bu-t-promoted robust strategy has been described for the regioselective synthesis of pyrrolo[3,4-b]quinolin-1-one and naphthyridin-1(2H)-one derivatives from o-alkynylquinolinecarbonitriles in good to excellent yields. The reaction proceeds through in situ transformation of the nitrile moiety into an amide group followed by the selective C-N bond formation through a 5-exo-dig or 6-endo-dig annulation reaction. Among the synthesized derivatives, 6-endo-dig naphthyridin-1(2H)-ones displayed good photophysical properties. The present approach is superior to other established methodologies as it avoids use of transition metals and column chromatographic purification and affords the products in high yields. Additionally, the current methodology provides several additional advantages, such as one-pot operation, high atom economy, broad substrate scope and a step-economical process.