Cyclo[ d.e.d.e.e.d.e.d.e.e. ]decakisbenzene, a New Cycloarene

The new parent hydrocarbon 1 is the second cycloarene (after kekulene) that consists of twelve symmetrically arranged benzene rings. 1 forms yellow crystals and was prepared by photocyclization of a partially hydrogenated benzophenanthrenophanediene. Compound 1 contains 40 π electrons, but can be formulated with an inner and an outer [4n + 2] π-electron perimeter.