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The selective immobilisation of chiral intermediates in asymmetric synthesis. / Rosemary Anne Dignan

Swansea University Author: Rosemary Anne Dignan

Abstract

The advantage of solid phase synthesis is that the products can be isolated and purified simply by filtration. However, the reaction conditions required often lead to different kinetic behaviour, differences in reactivity and solvation and other problems, not encountered in solution phase reactions....

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Published: 2002
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42631
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spelling 2018-08-02T16:24:29.9149986 v2 42631 2018-08-02 The selective immobilisation of chiral intermediates in asymmetric synthesis. 023865f80a4e52fc4e0bc68f428920c8 NULL Rosemary Anne Dignan Rosemary Anne Dignan true true 2018-08-02 The advantage of solid phase synthesis is that the products can be isolated and purified simply by filtration. However, the reaction conditions required often lead to different kinetic behaviour, differences in reactivity and solvation and other problems, not encountered in solution phase reactions. This thesis describes an approach at utilising the ease of purification associated with solid-phase synthesis without encountering the problems associated with two-phase reaction systems. It was achieved by selectively immobilising a bipyridyl-tagged chiral auxiliary and a bipyridyl-tagged oxazaborolidine catalyst by interaction by with a resin-bound transition metal upon completion of the solution-phase reaction. Chapter one is a literature review detailing some of the different approaches that have been reported in exploiting the benefits of solid-phase purifications whilst avoiding the associated problems. Soluble polymeric supports, fluorous labelling and some more unusual methods are investigated. Chapter two is a general introduction to how chiral auxiliaries can stereochemically influence reactions. Chiral auxiliary mediated alkylations, aldol reactions, conjugate additions and Diels-Alder reactions are focussed on. Chapter three details the complete synthesis of (R,R)-4,4'-bis-[1-(4,5-diphenyl-3-propionyl-imidazolidinonyl)-N-methyl]-2,2'-bipyridine, a bipyridyl-tagged chiral auxiliary. An investigation into its ability to reversibly bind to a resin-bound transition metal is then reported. Chapter four describes the extensive study on the reactivity of the tagged chiral auxiliary, concentrating on chiral alkylations, halogenations and aldol reactions. Chapter five is an account of how the selective immobilisation approach was extended to include chiral oxazaborolidine catalysts. A general introduction to oxazaborolidine catalysts is provided. The total synthesis of the bipyridyl-tagged oxazaborolidine, (S,S)-4,4'-bis-[4-(2-amino-3-hydroxy-3,3-diphenyl-propyl)phenoxymethyl]-2,2'-bipyridine is reported and the investigation into its ability to reversibly bind to a resin- bound transition metal is described. The chiral reduction of acetophenone using the tagged catalyst and the subsequent recovery of the catalyst is then explored. E-Thesis Organic chemistry. 31 12 2002 2002-12-31 COLLEGE NANME Chemistry COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:29.9149986 2018-08-02T16:24:29.9149986 Faculty of Science and Engineering School of Engineering and Applied Sciences - Chemistry Rosemary Anne Dignan NULL 1 0042631-02082018162509.pdf 10805389.pdf 2018-08-02T16:25:09.6800000 Output 5224325 application/pdf E-Thesis true 2018-08-02T16:25:09.6800000 false
title The selective immobilisation of chiral intermediates in asymmetric synthesis.
spellingShingle The selective immobilisation of chiral intermediates in asymmetric synthesis.
Rosemary Anne Dignan
title_short The selective immobilisation of chiral intermediates in asymmetric synthesis.
title_full The selective immobilisation of chiral intermediates in asymmetric synthesis.
title_fullStr The selective immobilisation of chiral intermediates in asymmetric synthesis.
title_full_unstemmed The selective immobilisation of chiral intermediates in asymmetric synthesis.
title_sort The selective immobilisation of chiral intermediates in asymmetric synthesis.
author_id_str_mv 023865f80a4e52fc4e0bc68f428920c8
author_id_fullname_str_mv 023865f80a4e52fc4e0bc68f428920c8_***_Rosemary Anne Dignan
author Rosemary Anne Dignan
author2 Rosemary Anne Dignan
format E-Thesis
publishDate 2002
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Chemistry{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Chemistry
document_store_str 1
active_str 0
description The advantage of solid phase synthesis is that the products can be isolated and purified simply by filtration. However, the reaction conditions required often lead to different kinetic behaviour, differences in reactivity and solvation and other problems, not encountered in solution phase reactions. This thesis describes an approach at utilising the ease of purification associated with solid-phase synthesis without encountering the problems associated with two-phase reaction systems. It was achieved by selectively immobilising a bipyridyl-tagged chiral auxiliary and a bipyridyl-tagged oxazaborolidine catalyst by interaction by with a resin-bound transition metal upon completion of the solution-phase reaction. Chapter one is a literature review detailing some of the different approaches that have been reported in exploiting the benefits of solid-phase purifications whilst avoiding the associated problems. Soluble polymeric supports, fluorous labelling and some more unusual methods are investigated. Chapter two is a general introduction to how chiral auxiliaries can stereochemically influence reactions. Chiral auxiliary mediated alkylations, aldol reactions, conjugate additions and Diels-Alder reactions are focussed on. Chapter three details the complete synthesis of (R,R)-4,4'-bis-[1-(4,5-diphenyl-3-propionyl-imidazolidinonyl)-N-methyl]-2,2'-bipyridine, a bipyridyl-tagged chiral auxiliary. An investigation into its ability to reversibly bind to a resin-bound transition metal is then reported. Chapter four describes the extensive study on the reactivity of the tagged chiral auxiliary, concentrating on chiral alkylations, halogenations and aldol reactions. Chapter five is an account of how the selective immobilisation approach was extended to include chiral oxazaborolidine catalysts. A general introduction to oxazaborolidine catalysts is provided. The total synthesis of the bipyridyl-tagged oxazaborolidine, (S,S)-4,4'-bis-[4-(2-amino-3-hydroxy-3,3-diphenyl-propyl)phenoxymethyl]-2,2'-bipyridine is reported and the investigation into its ability to reversibly bind to a resin- bound transition metal is described. The chiral reduction of acetophenone using the tagged catalyst and the subsequent recovery of the catalyst is then explored.
published_date 2002-12-31T03:53:20Z
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score 11.036116

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