Visible light-catalyzed intermolecular [2+2] cycloaddition of 1,2-dihydropyridines: A combined experimental and DFT study

In this article, the intermolecular [2+2] cycloaddition of 1,2-dihydropyridines was achieved for the first time by visible light-catalyzed. A series of novel and complex cyclobutane derivatives, the dimers of diethyl 1,2-diaryl-1,2-dihydropyridine-3,5-dicarboxylate, were synthesized efficiently with visible light catalysts under the irradiation of blue LED lamps. The density functional theory and time-dependent density functional theory were used to elucidate the detailed reaction processes, such as the reaction mechanism and the stereoselectivity of cycloaddition products.