Palladium and gold N-heterocyclic carbene complexes: synthesis and catalytic applications
Abstract
Palladium and gold-N-heterocyclic carbene (NHC) complexes have been studied in detail, with
focus on their synthesis and applications.
Palladium(II)-NHC complexes are known to be highly catalytically active complexes for numerous
organic reactions, specifically [PdCl(ƞ3-R-allyl)(NHC)] complexes are widely used in crosscoupling
chemistry. Based on this, an optimised, more facile and most importantly air-stable
synthesis was developed (Chapter 2). The preparation of a new class of Pd(II)-NHC complexes,
[NHC·H][Pd(ƞ3-R-allyl)Cl2], was optimised and applied to a wide range of NHC ligands (Chapter
2). Furthermore, the catalytic activity of [NHC·H][Pd(ƞ3-R-allyl)Cl2] was intensely studied in crosscoupling
chemistry (Chapter 3-6).
An environmentally friendly protocol was established for the Suzuki-Miyaura reaction using
[NHC·H][Pd(ƞ3-R-allyl)Cl2] in low catalyst loading. Both, the synthesis of the pre-catalysts as well
as the catalysis can be carried out under air and the mild conditions and enabled a diverse
substrate scope (Chapter 3).
The formation of C-N bonds is widely studied and of importance due to their appearance in a
wide range of molecules, particular in pharmaceutical reagents and natural products.
[IPr*·H][Pd(ƞ3-cin)Cl2] was found to be a highly catalytically active pre-catalyst in the Buchwald-
Hartwig amination as well as in ketone arylation (Chapter 4). Low catalyst loading, the use of a
green solvent and high yields created an efficient protocol.
An extensive study of the effect of different R-allyl ligands was performed for the Mizoroki-Heck
reaction (Chapter 5). Different [NHC·H][Pd(ƞ3-R-allyl)Cl2] pre-catalysts were tested and the
catalysis was optimised resulting in very low catalyst loading (0.1 mol%). Biologically interesting
heteroatom-containing aryl bromides were successfully coupled with styrene.
The catalytic activity of [NHC·H][Pd(ƞ3-R-allyl)Cl2] was further extended to the C-H activation of
terminal alkynes with aryl bromides (Chapter 6). The catalysis tolerated substrates containing
electron donating and withdrawing substituents. Furthermore the dimerization of terminal
alkynes to 1,3-enynes was investigated resulting in excellent yields.
Transition-Novel Au(I)-NHC complexes, namely [Au(Bpin)(NHC)] were synthesised and fully
characterised. In total, four complexes bearing different NHCs were synthesised and their
reactivity studied, revealing unique characteristics (Chapter 7).
Type
Thesis, PhD Doctor of Philosophy
Rights
Embargo Reason: Embargo period has ended, thesis made available in accordance with University regulations
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Description of related resources
Data underpinning Caroline Magdalene Zinser's thesis. Zinser, C.M., University of St Andrews, DOI: https://doi.org/10.17630/b43bc341-542d-4165-83bc-67c62e2d70baRelated resources
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