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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Some synthetic carbohydrate chemistry : natural product synthesis, rational inhibitor design and the development of a new reagent

Goddard-Borger, Ethan D January 2008 (has links)
Earnest carbohydrate research was initiated in the nineteenth century by several talented organic chemists. Carbohydrates, now known to play essential roles in a range of fundamental biological processes, are presently studied by a throng of scientists from many fields, including: biochemistry, molecular biology, immunology, structural biology, medicine, agriculture, pharmacology and, of course, chemistry. Organic chemistry remains as relevant to carbohydrate research as it has ever been; its practitioners, with their skills in synthesis and fundamental understanding of molecules, are truly indispensable. This thesis details various synthetic endeavours within the field of carbohydrate chemistry. It describes four projects with goals as diverse as natural product synthesis, rational inhibitor design and the development of new reagents in organic synthesis. The first chapter provides an account of the synthesis of compound 1, a potent germination stimulant present in smoke, from D-xylose. Many analogues of 1 were prepared from carbohydrates and evaluated as germination stimulants, which permitted the dissemination of several structure-activity relationships. Subsequent chapters describe the design and preparation of inhibitors for various carbohydrate-processing enzymes. Compounds 55 and 56 were sought after as putative synergistic inhibitors of a Vitis vinifera (grape) uridine diphospho-glucose:flavonoid 3-O-glucosyltransferase (VvGT1). It was hoped that crystallographic investigations of VvGT1-UDP-2/3 complexes by a collaborator, structural biologist Professor Gideon Davies, would aid in clarifying mechanistic aspects of this enzyme.Compounds 114, 115 and 118 were prepared as putative arabinanase inhibitors. Once again, this work was undertaken to assist in crystallographic studies that might provide a better understanding of how these enzymes operate. The thesis concludes by describing the development of compound 152.HCl, a novel reagent for the diazotransfer reaction. Previously, this reaction utilised trifluoromethanesulfonyl azide (TfN3), an expensive and explosive liquid with a poor shelf-life, to convert a primary amine directly into an azide. Reagent 152.HCl was developed to replace TfN3 in this useful synthetic transformation. A one-pot procedure enabled the simple and inexpensive preparation of 152.HCl, which was demonstrated to be shelf-stable, crystalline and, crucially, effective in the diazotransfer reaction.

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