El intercambio intramolecular de C-H/C-D en polifluorenos apilados cofacialmente a través de la activación de enlaces

Cheryl D Stevenson1, Matthew K Kiesewetter, Richard C Reiter

  • 1Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA. cdsteve@ilstu.edu

Resumen

La reducción de un electrón de los polifluorenos crea radicales aniónicos localizados en las unidades externas de fluoreno. Estos radicales se desproporcionan, formando dianiones que permiten el intercambio intramolecular de hidrógeno a bajas temperaturas.

Videos de Conceptos Relacionados

Introduction to Electrophilic Addition Reactions of Alkenes02:24

Introduction to Electrophilic Addition Reactions of Alkenes

The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product.
Addition and elimination reactions can be...
Thermal and Photochemical Electrocyclic Reactions: Overview01:26

Thermal and Photochemical Electrocyclic Reactions: Overview

Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.