Synthesis of 1,3-Disubstituted Imidazo[1,5-a]pyridines through Oxidative C-N Bond Formation from Aryl-2-pyridylmethanols and Their Fluorescent Study

A simple, effortless, and efficacious protocol for the synthesis of highly fluorescing imidazo[1,5-a]pyridines via copper catalyzed inter-/intramolecular C−N bond formation between readily available pyridyl alcohols with either benzyl amines or amino acids has been developed. This domino reaction is involved with alcohol oxidation/condensation/oxidative amination sequence to synthesize imidazo[1,5-a]pyridines in good to excellent yields. The fluorescence studies of these compounds indicated a bathochromic shift for the electron donating substituents, whereas a hypsochromic shift for the electron withdrawing substituents. Synthetic modification of the groups attached to the heterocyclic core showed a profound impact on the emission properties when subjected to pH and solvent polarity change.