Cobalt(II)-Catalyzed [2 + 2 + 2]/[4 + 2] Cycloaddition of 1,6-Heptadiynes with Maleimides

An efficient method for the synthesis of the polycyclic molecules <i>via</i> cobalt-catalyzed [2 + 2 + 2] followed by [4 + 2] consecutive cycloaddition reaction strategy has been devised. Sequential cycloaddition reactions of substituted 1,6-diynes with maleimides have been performed. This tandem cycloaddition approach has yielded polyheterocyclic compounds exhibiting remarkable diastereoselectivity and achieving yields ranging from good to excellent. Additionally, a potential reaction mechanism has been proposed to explain the observed cycloaddition process.