Highly regioselective and stereoselective photodimerization of azine-containing stilbenes in neat condition: An efficient synthesis of novel cyclobutanes with heterocyclic substituents

Abstract

We have developed a visible light promoted reaction of intermolecular [2 + 2] cycloaddition of heterostilbene molecules containing a phenyl ring with OMe donor groups and a 6-membered nitrogen-containing ring as an acceptor, which proceeds under mild conditions in water at room temperature. The corresponding cyclobutane derivatives were synthesized with yields of up to 57%. The efficiency of this photoreaction depends on the nature of the heterocyclic residue and the concentration of heterostilbenes. The mild reaction conditions and the absence of additives facilitate the reaction. This work provides a convenient and gentle method for the preparation of cyclobutanes.