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Updated: Jul 22, 2026

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations
13:09

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations

Published on: January 4, 2018

4 + 3 サイクル添加反応の非対称な有機触媒

Michael Harmata1, Sunil K Ghosh, Xuechuan Hong

  • 1Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA. harmatam@missouri.edu

Journal of the American Chemical Society
|February 20, 2003
PubMed
まとめ

研究者は,4 + 3サイクル添加のための非対称的有機触媒を開発しました. チラルアミンと酸が反応を触媒化し,シリオキシペンタディエナルとダイエンからエナティオメリックに濃縮された製品が得られました.

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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.
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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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Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
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