Photoinduced Rearrangements of 3,3′-Bis(arylbenzofurans)

Complex tetracyclic ring systems were assembled by a photoinduced rearrangement of 3,3′-bis(arylbenzofurans). Irradiation of 1 under N2 atmosphere yielded the benzonaphthofurans 2 in 75−90% yield. When the reaction was conducted under an O2 atmosphere in the presence of tetracyanoethylene (TCNE) a different reaction pathway was observed leading to the isolation of 3 as the major product. Also, the photochemical properties of these novel structures were investigated.