Synthesis, Structure, and Nucleophile-Induced Rearrangements of Spiroketones.

Three tetraketones based on the 2,2'-spirobiindan-1,1',3,3'-tetraone skeleton were prepared and investigated. All three compounds show spiroconjugation between their perpendicular pi-networks. The interaction results in lowering of the energy of the LUMO of the systems by ca. 0.2-0.3 eV as compared to non-spiroconjugated models. The spiroketones are susceptible to nucleophile-induced retro-Claisen condensations that lead to molecular rearrangements destroying spiro connectivity.