Arene synthesis by extrusion reaction. 9. Presumably planar derivatives of tribenzo[a,c,e]cyclooctene: synthesis of 10,11-methano-1H-benzo[5,6]cycloocta[1,2,3,4-def]fluorene-1,14-dione and 1,1,14,14-tetramethyl-10,11-methano-1H-benzo[5,6]cycloocta[1,2,3,4-def]fluorene