Synthesis of Benzophenone Nucleosides and Their Photocatalytic Evaluation for [2+2] Cycloaddition in Aqueous Media

Abstract

AbstractFour benzophenone nucleosides that are para‐substituted (–NH2, –NMe2, –OMe, and –Me) in relation to the carbonyl group were synthesized and characterized by their optical properties. The electron‐donating character of the substituents influenced the optical properties of these nucleosides, especially the bathochromic shift of the charge‐transfer band in their UV/Vis absorption spectra. The solubility of the synthetic nucleosides in aqueous solution allowed for a photocatalytic intramolecular [2+2] cycloaddition of a quinolone substrate to take place in H2O/MeCN by irradiating the mixture with 365 nm light‐emitting diode (LED) lamps. The MeO‐ and Me‐substituted benzophenone nucleosides were subjected to these reaction conditions in substoichiometric amounts. After prolonged irradiation times, substrate conversions competed with product decomposition. On the basis of our results, we determined that the Me‐substituted benzophenone nucleoside has potential applications in the development of photocatalytically active DNAzymes for both in vivo applications in chemical biology and enantioselective photocatalysis in aqueous solutions.