A Novel Hydrocarbon, 8,10-Dimethylidenetricyclo[7.1.1.02,7]undeca-2,4,6-triene: Synthesis of Benzopinane Skeleton via Di-π-methane Rearrangement of Benzonorbornadiene System

Article abstract of DOI:10.1002/hlca.19980810504

The [4 + 2] cycloadduct 17 of 2,3-dimethylidene-1,2,3,4-tetrahydro-1,4-methanonaphthalene and 4-phenyl-4H-1,2,4-triazole-3,5-dione (PTAD) was subjected to a triplet-sensitized di-π-methane rearrangement. Hydrolysis of the resulting urazol 18 gave the hydrocarbon 7. Hydrolysis of 18 at lower base concentrations led to isomeric stable semicarbazides 24 and 25, which were submitted NiO₂ or MnO₂ oxidation, to give the target compound 7, and oxidation products 26 and 27.