Coarctate

{
  "id": "MLC-T-CHM-002157",
  "term": "Coarctate",
  "field": "Chemistry",
  "definition": "A feature of a concerted reaction whose transition state involves two rings that meet at one atom, giving a constricted, figure-eight topology in which that atom simultaneously makes and breaks two bonds, two of its nonbonding orbitals exchanging roles with two bonding orbitals. It is an uncommon topology, distinct from the single closed cycle of pericyclic reactions and the open chain of linear reactions. The epoxidation of an alkene by dimethyldioxirane is a well-studied example.",
  "subject": "Organic and Biomolecular Chemistry",
  "references": [
    "PAC, 2022, 94, 353. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)' on page 387 (https://doi.org/10.1515/pac-2018-1010)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/coarctate/"
}