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
- and
-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
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
