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Title: Comparative chemistry of protected phosphines within the synthesis of cyclopropanes
Author: Clarke, C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2004
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On treatment with base, diphenylphosphinoyl esters 3 (X=O) give cyclopropanes 4 via a series of steps including intramolecular acyl and phosphinoyl transfer processes. β-Substituted esters have been shown to give cyclopropanes with high diastereoselectivity. This thesis describes the synthesis of optically active β-substituted esters using Evans’ alkylation methodology and their use in the stereocontrolled synthesis of substituted cyclopropanes. It was found that that phosphine oxide 1 (X=O) is unstable in the conditions of the alkylation reaction and the corresponding phosphine borane 1 (X=BH3) was employed with greater success. The thesis also describes investigations into the potential formation of cyclopropanes 4 from esters 3 (X= BH3/S) without prior conversion to the phosphine oxide 3 (X=O). It has been proposed that a phosphine ester is a key intermediate in the formation of cyclopropanes 4 from diphenylphosphinoyl esters 3 (X=O). Detailed in this thesis, is an investigation into the synthesis of optically active cyclopropanes 8 from phosphonate esters 7 prepared by an Evans’ alkylation route. Also included in this thesis are studies into the relative rates of deprotonation and the palladium-catalysed hydrogenation reactions of allyl phosphine oxides, boranes and sulfides. Phosphine oxides have also been used in the synthesis of cyclopropanes via a route analogous to that of the Wadsworth-Emmons cyclopropanation reaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available