Pericyclic Reactions: Aromaticity of Transition States
Aromaticity of Transition States: Summary
If extension of the definition of aromaticity is applied to nonplanar systems, s orbitals and Möbius aromatic compounds, the rules can be summarized in one sentence:
- Selection Rules for Pericyclic Reactions
- Pericyclic reactions preferrably pass through aromatic transition states.
- Hückel systems exhibit an even number of sign inversions including zero in the cyclic delocalized basis set, regardless how the signs are chosen. They are aromatic with 4n+2 electrons.
- Möbius systems exhibit an odd number of sign inversions in the cyclic delocalized basis set, regardless how the signs are chosen. They are aromatic with 4n electrons.