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Updated: May 23, 2025

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循环子的脱光异构化

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
概括

这项研究引入了一种简单的光化学方法来异构循环,从而产生有价值的区域异构产品. 这种新技术使用近紫外线和布伦斯特德酸催化剂来有效地反应.

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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
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The chiral α-carbon of the carbonyl compound is the stereocenter of the molecule. As shown in the figure below, when such a carbonyl compound undergoes racemization under an acidic or basic condition, an achiral enol is formed.
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