Reactivity of Dipyrromethanes towards Azoalkenes: Synthesis of Functionalized Dipyrromethanes, Calix[4]pyrroles, and Bilanes

The introduction of side chains at the 1‐ and 9‐positions of dipyrromethanes was explored by using the hetero‐Diels–Alder reaction of azoalkenes. New 5,5′‐diethyldipyrromethanes and 5‐phenyldipyrromethanes that were functionalized with open‐chain hydrazone moieties, including derivatives with tetrazolyl groups, were prepared. Furthermore, the synthesis of new calix[4]pyrroles and bilanes was achieved by employing the bis(hetero‐Diels–Alder) reaction of azoalkenes with 5,5′‐diethyldipyrromethane.