Abstract: Entry into the benzo (CH) ro series has been gained by benzyne cycloaddition to 7, 8-dichlorobicyclo-[4.2. 0] octa-2, 4-diene and subsequent dechlorination of the adducts. Sensitized photolysis of the anti-7, 8-benzo-tricyclo [4.2. 2.02~ 5] deca-3, 7, 9-triene (4) so produced gave rise chiefly to benzobasketene (5) and benzosemibullvalene derivative 6. Thermal rearrangement of 4 afforded exclusively cis-4b, Sa-dihydrophenanthrene (8). The ...
