dc.contributor.author | Minicone, Fabrizio | |
dc.date.accessioned | 2015-09-21T11:20:25Z | |
dc.date.available | 2015-09-21T11:20:25Z | |
dc.date.issued | 2014-10-04 | |
dc.identifier.citation | Minicone, F. 2014. STEREOSELECTIVE SYNTHESIS OF CYCLOPROPANES WITH QUATERNARY CARBON CENTRES. Queen Mary University of London | en_US |
dc.identifier.uri | http://qmro.qmul.ac.uk/xmlui/handle/123456789/8766 | |
dc.description | PhD | en_US |
dc.description.abstract | Multi-substituted optically pure cyclopropanes are important motifs present in many
agrochemicals, pharmaceuticals and materials employed in manifold applications. Their synthesis is
challenging due to both the strained conformation and the need to control both the relative and
absolute stereochemistry. This thesis describes an investigation of the scope of the
Wadsworth-Emmons cyclopropanation, highlighting it as a potential efficient methodology for
diastereoselective and enantiospecific synthesis of these valuable ring systems.
Chapter 1 is an introduction to the cyclopropanation protocols and is split in two
subsections. The first is a description of the currently most exploited synthetic pathways to
cyclopropanes, with analysis of their substrate scope and critical analysis of their limitations as
compared to potential of the Wadsworth-Emmons cyclopropanation (Sections 1.1 to 1.3). The latter
section consists of a review on the history and the evolution of this procedure and introduces the
preconditions for the development of the project (Sections 1.4 to 1.17).
Chapter 2 describes the results and discussion, introducing the use of novel alkyl-substituted
triethyl phosphonoacetates to yield cyclopropyl-esters containing quaternary stereocentres. The
high yields and the excellent trans-diastereoselectivity values obtained (proved by X-ray
crystallography) allowed the proposal of a suggested reaction mechanism, which is supported by
the subsequent experiments carried out in the presence of other functional groups, e.g. other
carbonyls, nitriles, hetero-aromatics, substituted phenyl rings. This study was further extended to
examine the effect of fluorine atom, due to its importance in biologically active environments. The
study on the stereochemistry of the Wadsworth-Emmons cyclopropanation has been strongly
supported by a range of X-ray crystal structures of the cyclopropane products. The chapter ends
with an empirical set of guidelines, helpful for the design of successful cyclopropanations.
Chapter 3, describes the experimental methods in full as well as full characterisation of the products obtained. Literature references, noted throughout the thesis, are listed in the final chapter. | en_US |
dc.description.sponsorship | EPSRC | en_US |
dc.language.iso | en | en_US |
dc.publisher | Queen Mary University of London | en_US |
dc.subject | Biological and Chemical Sciences | en_US |
dc.subject | cyclopropanation | en_US |
dc.title | STEREOSELECTIVE SYNTHESIS OF CYCLOPROPANES WITH QUATERNARY CARBON CENTRES | en_US |
dc.type | Thesis | en_US |
dc.rights.holder | The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author | |