Loughborough University
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Asymmetric synthesis : approaches via enantiomerically pure acetal and oxazoline ligands

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posted on 2013-12-06, 15:27 authored by Louise M. Newman
This thesis describes the synthesis of novel ligands that include enantiomerically pure acetal and oxazoline moieties. These ligands are utilised in a number of metalmediated asymmetric syntheses. All asymmetric acetals and pyridine based acetals are synthesised in good yield in a single step from their corresponding enantiomerically pure diols. C2 symmetric bisacetals are investigated as ligands in the organolithium and Grignard additions to benzaldehyde with promising results. C2 symmetric bisacetals and pyridine based acetals are tested for their ability to induce asymmetry in copper(l) catalysed cyclopropanation of styrene using ethyl diazoacetate and the lanthanide(lII) catalysed Diels-Alder cycloaddition involving Danishefsky's diene with little success. Enantiomerically pure phosphinooxazoline ligands are available in good yield in two steps from their corresponding enantiomerically pure aminoalcohols. Enantiomerically pure acetal substituted pyridines and phosphinooxazoline ligands are considered in the rhodium (I) catalysed hydrosilylation of ketones. Reaction conditions for the more successful phosphinooxazoline ligands are optimised. Using these ligands a range of enantiomerically enriched alcohols is presented in good yield and enantiomeric excess. Novel phosphinooxazoline ligands are applied to the palladium(O) catalysed allylic substitution reaction with excellent enantioselectivities of the substitution product.



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© Louise M. Newman

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A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.


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