Rearrangements HOMO-LUMO theory

Fukui and Inagaki have proposed an orbital interaction role for catalysts in the valence isomerization of tricyclo[4,2,0,0 ]octa-3,7-diene and in the rearrangement of syn-tricyclo[4,2,0,0 ]octane to tetrahydrosemibulvalene. The importance of the interactions with the HOMO and LUMO is stressed, and perturbation theory is used to explain how the catalysis can assist an energetically- or symmetry-disfavoured process. 

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