Synthesis and structure of 1',4'-diphenyl-1a,1',4',4'',5'',9b-hexa-hydro-2''H-di-spiro-[cyclopropa[l]phenanthrene-1,2'-[1,4]ep-oxy-naphthalene-3',3''-thio-phene].

The title compound, C(39)H(30)OS, was inadvertently prepared as a Diels-Alder adduct between 1,3-di-phenyl-isobenzo-furan and 3-(1a,9b-di-hydro-1H-cyclo-propa[l]phenanthren-1-yl-idene)tetra-hydro-thio-phene. A combination of fused, bridged, and spiro-cyclic ring systems are all featured within a single mol-ecular structure of this highly crowded polycyclic compound.