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|Title: ||Asymmetric catalysis using titanium and palladium|
|Authors: ||Sesay, Simon J.|
Kinetic resolution epoxidation
|Issue Date: ||1998|
|Publisher: ||© Simon J. Sesay|
|Abstract: ||This thesis describes, in detail, the synthesis of novel heterobidentate ligands. These
ligands were subsequently used in palladium catalysed allylic substitution reactions to
synthesise enantiomerically enriched alkylated products. The thesis also describes
novel approaches to asymmetric catalysis, in particular asymmetric epoxidation
derived from Katsuki-Sharpless methodology.
Chapter 1 - This chapter reviews the literature, discussing the significant synthetic
advancements in asymmetric catalysis in the past 10-15 years.
Chapter 2 - This chapter describes in detail the synthesis of new heterobidentate
ligands containing nitrogen and phosphorus ligating atoms. These ligands are based
on imines containing enantiomerically pure asymmetric centres in an alpha position to
the nitrogen moiety. Other ligands that were synthesised were derived from C2-
symmetric diamines, also containing an asymmetric centre alpha position to the
nitrogen, that produce ligands with the nitrogen functionality contained in a ring.
Chapter 3 - This chapter describes the use of the novel ligands synthesised in
Chapter 2 in palladium catalysed allylic substitution reactions. The racemic substrate,
1 ,3-diphenyl-3-acetoxy-1-propene, was alkylated to produce an enantiomeric enriched
alkylated product. The alkylated product was obtained with up to 77 % enantiomeric
excess. The reaction was conducted with a palladium catalyst in the presence of a
novel ligand using dimethyl malonate as a nucleophile. The development and
optimisation of these ligands within this reaction is discussed.
Chapter 4 - This chapter discusses some novel approaches to asymmetric
epoxidation. The epoxidation is based on methodology developed by Katsuki and
Sharpless. This epoxidation relies on the substrate containing an up-unsaturated
alcohol. The chapter discusses the use of a reversible nucleophile in the form of
cyanide. The nucleophile is designed to react with a substrate to provide an upunsaturated
cyanohydrin, suitable to undergo a Katsuki-Sharpless epoxidation. Once the asymmetric epoxidation is complete, the nucleophile would be removed. This
chapter describes the attempts to develop the principle further. An improvement to
the system would be to provide an environment capable of sustaining a dynamic
Chapter 5 - This chapter contains the experimental which provides the exact details of
the reactions reported in the thesis.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Chemistry)|
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