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Updated: May 23, 2025

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
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Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

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交互電離結合により,ステリックに阻害されたC{sp2) -C{sp3) 結合:NiとCoは補完的反応性を提供する

Tianrui Wu1, Anthony J Castro1, Kasturi Ganguli1

  • 1Department of Chemistry, UW-Madison, Madison, Wisconsin 53706, United States.

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

この研究は,クロス電子結合反応でニッケルとコバルトの触媒を用いて,ステリカルに阻害された炭素-炭素結合を作成するための新しい方法を導入しています. これらの発見は 複雑な分子構造のための 合成能力を拡張します

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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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The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
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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.
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The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
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