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Synthesis of functionalised silanes for use in the asymmetric allylation reaction

MacDonald, Claire (2010) Synthesis of functionalised silanes for use in the asymmetric allylation reaction. PhD thesis, University of Glasgow.

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Abstract

Asymmetric allylation of aldehydes with allyltrichlorosilane reagents, in recent years, has become a powerful synthetic tool towards the enantioselective construction of homoallylic alcohols. In general, the reaction displays good diastereocontrol. Thus, when the allylation is carried out in the presence of a Lewis base, the homoallylic alcohols anti-3 and syn-4 are stereospecifically obtained from the (E)-2 and (Z)-2 silanes, respectively, indicating that the reaction is likely to proceed via a cyclic, chair-like transistion state. Herein, the synthesis of isomerically pure allylsilanes 2, functionalised in the γ-position is reported. This has enabled the range of valuable synthetic intermediates available via the asymmetric allylation reaction of various aromatic aldehydes to be extended. The resultant homoallylic alcohols have two new stereogenic centres. These molecules can now undergo an intramolecular SN2 reaction to afford the corresponding vinyl epoxides 5 and 6 with retention of the relative stereochemistry. A variety of chiral Lewis bases, including pyridine N-oxides and phosphine oxides, were synthesised and screened for asymmetric induction. The most notable result was achieved using chiral phosphine oxide BINAPO, which produced the syn-homoallylic alcohol 4 in 50 % ee.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Asymmetric Allylation Reaction
Subjects: Q Science > QD Chemistry
Colleges/Schools: College of Science and Engineering > School of Chemistry
Supervisor's Name: Kocovsky, Prof. Pavel
Date of Award: 2010
Depositing User: Miss Claire MacDonald
Unique ID: glathesis:2010-1915
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 17 Jun 2010
Last Modified: 10 Dec 2012 13:48
URI: http://theses.gla.ac.uk/id/eprint/1915

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