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Intramolecular radical additions to pyridines, quinolines and isoquinolines

Intramolecular radical additions to pyridines, quinolines and isoquinolines
Intramolecular radical additions to pyridines, quinolines and isoquinolines
This thesis is concerned with the development of intramolecular radical additions onto nitrogen containing heteroaromatics. Notably, 6-exolendo-tng radical cyclisations to C-2, C-3 and C-4 of pyridines and quinolines and C-3 and C-4 of isoquinolines have all been shown to be facile processes at neutral pi7. Cyclisations follow a chain pathway in which aromaticity in the heteroaromatic is re-established through loss of a hydrogen atom. S-exolendo Txig radical cyclisations to quinolines fail and appear to be more akin to 5-endo-tng processes than 5-exo-tng processes. Reactions that employ aryl iodides as radical precursors generally proceed more efficiently than related cyclisations employing aryl bromides.
It has been shown that the nature of the tether used to conjoin the radical precursor to the heteroaromatic can have a significant baring on the outcome of a reaction. When a fully saturated two carbon tether is used to conjoin an aryl radial to a pyridine an unprecedented rearrangement by zpi'o-radical cyclisation (5-exo-trig) - alkyl migration - aromatisation sequence competes with the 6-exo/endo-tvig cyclisation pathway. When an E alkene is used to tether the radical precursor to a pyridine, or if the heteroaromatic is a quinoline or isoquinoline, only the 6-exolendo-tng pathway is followed. Using the methodology developed, approaches to the alkaloid avicine are discussed. A comparison of various techniques commonly employed to generate aryl radicals from aryl iodides is also reported. A literature review concerning radical additions to nitrogen containing heteroaromatics is presented.
University of Southampton
Sutton, Benjamin J.
ca6c5fe1-cdee-49b2-8e58-97d4d6072d50
Sutton, Benjamin J.
ca6c5fe1-cdee-49b2-8e58-97d4d6072d50
Harrowven, David
bddcfab6-dbde-49df-aec2-42abbcf5d10b

Sutton, Benjamin J. (2003) Intramolecular radical additions to pyridines, quinolines and isoquinolines. University of Southampton, Doctoral Thesis, 304pp.

Record type: Thesis (Doctoral)

Abstract

This thesis is concerned with the development of intramolecular radical additions onto nitrogen containing heteroaromatics. Notably, 6-exolendo-tng radical cyclisations to C-2, C-3 and C-4 of pyridines and quinolines and C-3 and C-4 of isoquinolines have all been shown to be facile processes at neutral pi7. Cyclisations follow a chain pathway in which aromaticity in the heteroaromatic is re-established through loss of a hydrogen atom. S-exolendo Txig radical cyclisations to quinolines fail and appear to be more akin to 5-endo-tng processes than 5-exo-tng processes. Reactions that employ aryl iodides as radical precursors generally proceed more efficiently than related cyclisations employing aryl bromides.
It has been shown that the nature of the tether used to conjoin the radical precursor to the heteroaromatic can have a significant baring on the outcome of a reaction. When a fully saturated two carbon tether is used to conjoin an aryl radial to a pyridine an unprecedented rearrangement by zpi'o-radical cyclisation (5-exo-trig) - alkyl migration - aromatisation sequence competes with the 6-exo/endo-tvig cyclisation pathway. When an E alkene is used to tether the radical precursor to a pyridine, or if the heteroaromatic is a quinoline or isoquinoline, only the 6-exolendo-tng pathway is followed. Using the methodology developed, approaches to the alkaloid avicine are discussed. A comparison of various techniques commonly employed to generate aryl radicals from aryl iodides is also reported. A literature review concerning radical additions to nitrogen containing heteroaromatics is presented.

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Published date: 1 January 2003

Identifiers

Local EPrints ID: 426728
URI: http://eprints.soton.ac.uk/id/eprint/426728
PURE UUID: b506c0f2-3b3f-4f48-8ebf-e7bff86d004e
ORCID for David Harrowven: ORCID iD orcid.org/0000-0001-6730-3573

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Date deposited: 11 Dec 2018 17:30
Last modified: 14 Aug 2019 00:38

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Contributors

Author: Benjamin J. Sutton
Thesis advisor: David Harrowven ORCID iD

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