The rapid synthesis of π-extended azacorannulenes

In this account we describe our recent development of rapid syntheses of π-extended azacorannulenes. The key to successful synthesis is the use of polycyclic aromatic azomethine ylides, which exhibit extremely high reactivity in sequential 1,3-dipolar cycloadditions with alkenes and alkynes followed by oxidation to form fused pyrroles. This efficient construction of the polycyclic pyrrole structure has led to the rapid synthesis of various π-extended azacorannulenes, which are characterized by their extended π-surface and highly curved, bowl-shaped structures. The present study provides useful insights toward the bottom-up synthesis and property elucidation of heteroatom-containing fullerenes and their fragment molecules.