pseudopericyclic

https://doi.org/10.1351/goldbook.P04932
A
concerted transformation
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 enol prototropy of pentane-2,4-dione (acetylacetone).
Because the π- and σ-atomic orbitals that interchange roles are orthogonal, such a reaction does not proceed through a fully
conjugated transition state
and is thus not a
pericyclic reaction
and therefore not governed by the rules that express
orbital symmetry
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]