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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

A new total synthesis of (-)-(3R)-inthomycin C via O-directed alkyne free radical hydrostannation and a new method for ketone enolate C-acylation

Grabski, Milosz Kamil January 2014 (has links)
Ketone enolate C-acylation is certainly one of the fundamental transformations in organic chemistry, providing access to a wide range of building blocks and natural products. However, there are limitations to the currently existing methods which occasionally prove inadequate for sterically demanding or chemically sensitive systems. Such was the case of the antitumour natural product (-)-echinosporin, which led to the development of a new mild protocol for the C-acylation of ketone enolates. The use of MgBr2·Et2O/Pr2NEt/DMAP in the presence of a suitable pentafluorophenyl electrophile not only provided a desired advanced intermediate necessary for the synthesis of mentioned natural product, but also gave access to a wide range of -ketoesters, including· -keto thioesters and· - thionoesters which often are hard to obtain using previously developed protocols. Herein, we report the development and scope of the aforementioned protocol in simple aromatic as well as highly complex aliphatic systems. Total synthesis is unquestionably a crucial part of the organic synthesis field, providing access to a wide range of natural products which are often no longer accessible by other means, and providing a platform for further development of the organic synthesis protocols. As a contribution to the ever developing organic synthesis scene, our group has in recent years embarked on a quest to further expand the scope and capabilities of the Ph3SnH/Et3B O-directed free radical alkyne hydrostannation method developed in Hale's laboratories in 2005. The antitumour natural product (-)-inthomycin C attracted our attention in this respect because it provided an ideal test vehicle for studying whether unfavourable syn or gauche-gauche pentane repulsive interactions could thwart the O-directed hydrostannation or palladium cross-coupling steps. Therefore, the work described within provides a detailed discussion of the newest total synthesis of (-)-(3R)inthomycin C in 17 steps. The critical point of the project arose from the 3C-stereocentre controversy existing in the literature, yet not remarked on elsewhere. Consequently, a careful analysis of the absolute configuration of(-)-inthomycin C, and its significant relation to the optical rotation of the product, has been performed and widely discussed in the present work
2

The enantioselective synthesis of histidine analogues

Kumar, Amit January 2005 (has links)
No description available.
3

Approaches to single enantiomers of cyclopropanes

Bromley, Graham January 2003 (has links)
No description available.
4

Towards the asymmetric synthesis of (-)-rocaglamide and Optimisation of the Mizoroki-Heck reaction using design of experiment

Staubitz, Anne January 2007 (has links)
No description available.
5

Cyclic sulfamidates as versatile intermediates for N-heterocycle construction : applications in total synthesis

Bower, John F. January 2007 (has links)
No description available.
6

Developing new asymmetric transformations for organic synthesis

Fang, Guangyu January 2004 (has links)
No description available.
7

Addition of sulfonium ylides to chiral aldehydes : stereocontrol and its application in the total synthesis of swainsonine

Bi, Jie January 2007 (has links)
No description available.
8

Computational studies of spin-forbidden organometallic chemistry : ligand binding and C-H bond activation

Carreon-Macedo, Jose-Luis January 2006 (has links)
No description available.
9

Asymmetric epoxidation of carbonyl compounds mediated by sulfonium ylides

Richardson, Jeffery January 2004 (has links)
No description available.
10

The synthesis and application of a C₃ symmetric amine and phosphine ligand

Eley, Helen January 2004 (has links)
No description available.

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