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Updated: Mar 19, 2026

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

Published on: July 17, 2020

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可視光照射によって誘発される2~1H) -キノロンのエナチオセレクティブの分子間 [2+2]光サイクル添加反応

Andreas Tröster1, Rafael Alonso1, Andreas Bauer1

  • 1Department Chemie and Catalysis Research Center (CRC), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.

Journal of the American Chemical Society
|June 9, 2016
PubMed
まとめ

キラルチオキサントン触媒は,反選択的分子間 [2 + 2] 光環添加反応を可能にします. この方法では,可視光を使用したサイクロブタン製品に対して高い地域選択性,二重選択性,およびエナティオメール過量が得られます.

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Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
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Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
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In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
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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.
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