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Updated: May 23, 2025

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers
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サイクルエノンの解結合光異性化

Lukas Blank1, Jungwon Kim2, Constantin G Daniliuc1

  • 1Institute for Organic Chemistry, University of Münster, Corrensstraβe 36, Münster 48149, Germany.

Journal of the American Chemical Society
|March 7, 2025
PubMed
まとめ

この研究は,価値あるレジオアイソメリック製品の生成を可能にする,サイクルエノンのイソメリゼーションのための単純な光化学的方法を導入しています. この新しい技術では,近紫外線とブロンステッド酸の触媒を用いて,アルケンの効率的な反応を図る.

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Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
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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.
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