## pseudopericyclic

https://doi.org/10.1351/goldbook.P04932
A @C01234@ is pseudopericyclic if the primary changes in bonding occur within a cyclic array of atoms at one (or more) of which nonbonding and bonding atomic orbitals interchange roles. A formal example is the enol $$\rightarrow$$ enol prototropy of pentane-2,4-dione (acetylacetone).
P04932.png
Because the $$\pi$$- and $$\sigma$$-atomic orbitals that interchange roles are orthogonal, such a reaction does not proceed through a fully @C01267@ and is thus not a @P04491@ and therefore not governed by the rules that express @O04320@ restrictions applicable to pericyclic reactions.
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1154 [Terms] [Paper]