One‐Step Facile Synthesis of Fused All‐Carbon Cyclododecadiene and Cyclohexadecatetraene

All-carbon macrocyclic compounds are useful chemical components for drug molecules, nanomaterials, and catalyst supports. The access of macrocyclic compounds is trapped in the absence of efficiency and flexible synthetic approaches besides obtaining from natural products. In this study, the first case of synthetic fused all-carbon cyclododecadiene and cyclohexadecatetraene through the multistep tandem cyclization of an α,3-dehydrotoluene-type reactive intermediate derived from pentadehydro-Diels-Alder (PDDA) reaction with conjugated olefins was reported. This method circumvents the use of specific catalysts, complex operations, and low yields. Density functional theory calculations reveal the formation of biradical intermediates, which play a crucial role in optimal reaction process.