THE GENERATION OF ANTHRA[2,3-C]FURAN VIA AROMATIC-RING HOMOLOGATION OF NAPHTHO[2,3-C]FURAN

Anthra[2,3-c]furan, a higher aromatic homologue of isobenzofuran, has been predicted to be a highly reactive polyene lacking any significant aromatic character despite being a 14 pi-electron system. We have gen erated this previously inaccessible molecule by acid-catalyzed elimina tion of methanol from an acetal precursor, and have trapped it with se veral dienophiles. The overal reaction sequence describes an aromatic- ring homologenation of naphtho[2,3-c]furan to anthra[2,3-c]furan.