Styrene oxide reacted with group 5 and 6 metal halides in 1,2-dichloroethane to afford an 8-membered ring compound, 2,3,6,7-dibenzo-9-oxabicyclo[3,3,1]nona-2,6-diene. When the reaction was carried out in benzene instead of 1,2-dichloroethane as a solvent, unexpected new 8-membered ring product, tribenzobicyclo[3.3.2]decatriene, and 1,1,2-triphenylethane were obtained. The structures of the 8-membered ring compounds were confirmed by X-ray analysis.