Formation of complex cyclic compounds <i>via</i> a dehydrogenative Diels–Alder reaction

Reported herein is an unprecedented annulation strategy for macrocyclic compounds. This reaction facilitates the generation of α,3-dehydrotoluene (DHT) intermediates through a pentadehydro-Diels-Alder process, wherein subsequent DHT variants react with 1,6-diphenylhexa-1,3,5-triene to afford macrocyclic compounds with a broad substrate scope. Density functional theory computations support a zwitterionic intermediate process. Another product with a different skeleton is obtained by changing the reaction conditions.