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|Title: ||Homogeneous gold catalysts : development of applications for gold(I) catalysts bearing N-heterocyclic carbene ligands|
|Authors: ||Müller, Ruben S. Ramon|
|Supervisors: ||Nolan, Steven P.|
|Issue Date: ||Nov-2011|
|Abstract: ||Recently established as an excellent activator for π-systems, efforts made in gold
chemistry have increased enormously, resulting in a new ‘Gold Rush’ in chemistry. This
thesis is a small contribution to it.
There are two main aspects dominating the following chapters: gold catalysts
bearing N-heterocyclic carbenes (NHCs) as supporting ligand, and H₂O assisted
The initial motivation for the presented work was to specifically demonstrate the
potential of [(NHC)AuCl] as suitable catalysts for both known and new organic
transformations and to establish these commercially available catalysts in gold
chemistry, a field currently dominated by phosphine bearing gold complexes. Water
mediated catalysis became the next repeatingly occurring aspect of this thesis by
pursuing this initial aim and finding water as a useful solvent or agent, respectively.
Various useful applications for gold-NHC complexes are presented, starting with
the Meyer-Schuster rearrangement of propargylic alcohols as a continuation of the work
realized with propargylic acetates by the Nolan group in early investigations on gold
catalysts. Next, a study on alkyne hydration is presented with focus on low catalysts
loadings to establish gold catalysts as a powerful choice for such a highly relevant
reaction. The catalytic system is then advantageously adapted to a silver-free variation,
still active at low catalyst loadings and with further mechanistic insight.
Inspired by gold activation of alkynes, a gap of reactivity in gold catalysis is closed
by a successful demonstration of nitrile hydration, a functionality previously thought to
be inert towards gold activation. In this context, formation and role of dinuclear
hydroxy-bridged gold complexes is investigated highlighting these complexes as a
possible resting state of gold complexes in the presence of water.
Next, the formation of furanones via alkoxylation/lactonization of propargylic
propiolates is presented, an observation initially made when exploring the scope of the
The dissertation finally closes with the gold-catalyzed formation of amides, this
time however achieved from aldoximes reacting via dehydration/hydration mechanism.|
|Publisher: ||University of St Andrews|
|Appears in Collections:||Chemistry Theses|
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