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Title: Transition metal oxazoline complexes : synthesis and applications in asymmetric catalysis
Authors: Garratt, Shaun Anthony.
Award date: 1998
Presented at: University of Leicester
Abstract: This thesis describes the synthesis and chemistry of "(arene)Ru" and "Cp*Rh" complexes of chiral oxazoline-containing ligands and their use as asymmetric Lewis-acid catalysts.;Chapter One introduces important aspects of asymmetric catalysis, then describes in more detail the use of chiral oxazoline ligands to induce high levels of stereocontrol in many important catalytic reactions.;Chapter Two initially introduces the area of chiral half-sandwich complexes, describing their chemistry and their use in asymmetric synthesis. The synthesis and characterisation of half-sandwich ruthenium and rhodium complexes of C2-symmetric bis-oxazoline ligands is then described (these complexes are chiral at ligand only). The complex solution behaviour of the aqua species [M(OH2)(N-N)(ring)]2+ was extensively investigated. In the latter part of the chapter, the synthesis of half-sandwich complexes of unsymmetrical oxazoline ligands is described. In this case, the complexes are chiral-at-metal and the relative diastereoselectivities of formation and configurational stabilities in solution are discussed in detail and were generally found to be very high. Numerous X-ray structures have been obtained and variable temperature and 2D NMR techniques have been employed to study the solution behaviour of the complexes.;Chapter Three describes the use of the half-sandwich complexes as asymmetric Lewis-acid catalysts. Complexes [Ru(OH2)(N-N)(mes)](SbF6)2 (N-N = pymox, benbox) were found to be efficient and enantioselective catalysts for the Diels-Alder reaction of acrylic dienophiles with simple dienes. A selection of different catalysts and substrates were used, with varying results. Other Lewis-acid catalysed reactions (including the Hetero-Diels Alder and Mukaiyama Aldol) were studied, but with less success. The inverse electron-demand Hetero Diels-Alder reaction was identified as an area worthy of further study.
Type: Thesis
Level: Doctoral
Qualification: PhD
Rights: Copyright © the author. All rights reserved.
Appears in Collections:Theses, Dept. of Chemistry
Leicester Theses

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