Microwave-Assisted Synthesis of Base Modified Furo[3,2-c]quinolone Nucleosides and Insights into Their Photophysical Properties

A green, catalyst free, one-pot, gram scale microwave-assisted synthesis of fluorescent furo [3,2-c]quinolone nucleoside analogues has been successfully developed using 2-Me-THF as a greener solvent. This method, employing 3′,5′-di-O-acetyl-5-formyl-2′-deoxyuridine, alkyl isocyanides, and differently substituted 4-hydroxyquinolones, achieved product yield up to 92 %, which offers high atom economy, reduced reaction time and simple work-up procedure. The products were fully characterized by spectroscopic techniques and single crystal X-ray analysis with DFT analysis conforming the electronic structures. Fluorescence studies revealed strong emission (∼450 nm), large Stokes shifts (59–98 nm), and high quantum yields (0.053–0.595). Solvatochromism studies highlighted their environmental sensitivity, indicating potential applications in nucleic acid research and bio-imaging.