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Research output: Thesis › Doctoral Thesis
Research output: Thesis › Doctoral Thesis
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TY - BOOK
T1 - Synthesis of Diverse Metalloid Scaffolds via Transition Metal Catalysis
AU - Roberts, Dean
PY - 2024
Y1 - 2024
N2 - The work within this thesis describes developments in platinum catalysedhydrometallation for the synthesis of a range of diverse metalloid scaffolds.Chapter 1 contains a discussion of the application of organometalloid scaffoldsin modern organic chemistry, as well as the widespread application of platinumcomplexes in the synthesis of said scaffolds. Notable developments in the fieldare summarised and the generally accepted mechanisms through which thesereactions proceed are discussed.Chapter 2 examines the limitations of previous platinum complexes in catalysingselective hydrosilylations and the reasons for these limitations, as well asdiscussing the approaches to, and applications of, allylic amines in organicchemistry. The development of a PtCl2Xantphos catalyst to selectively carry outthe hydrosilylation of propargylic amines and their derivatives is detailed as wellas an investigation of the substrate scope. The synthetic utility of the products isinvestigated resulting in the development of a remarkably mild aziridinationprocedure.Chapter 3 builds on the previous aziridination procedure, demonstrating theapplicability of the same sequence to access a range of diverse oxetanes by ahydrosilylation/cyclisation sequence. Previous approaches to oxetanes arediscussed, as well as the utility of the scaffold in modern organic and medicinalchemistry. Attempts to expand the methodology to the synthesis of otherheterocycles is also discussed.Chapter 4 details the study of platinum complexes in the context ofhydrostannylation chemistry. Previous approaches to the scaffold are discussed,as well as the surprising lack of platinum-based catalyst systems. The effect ofligand denticity on stereoselectivity is reported, with a ligand controlledstereodivergency reported. Using a PtCl2(XPhos)2 catalyst system, a range ofdiverse organotin scaffolds are synthesized, and the benefits and limitations ofthe system in comparison to previous catalysts is discussed. A telescoped hydrometallation/cross-coupling sequence is developed to minimize the need tohandle relatively unstable and toxic stannylated intermediates.Chapter 5 explores the application of platinum complexes bearing both NHC andphosphine ligands as hydrosilylation catalysts. The synthesis of a broad range ofimidazolium salts is presented, alongside the synthesis of several platinumcomplexes via an organosilver intermediate. The efficacy of the complexestowards hydrosilylation is evaluated, and their poor performance rationalized inthe context of similar complexes employed in the literature.Chapter 6 provides overall conclusions from the work presented as well as adiscussion of further avenues of study.Chapter 7 provides bibliographic data for the thesis. Relevant characterisationdata for novel compounds or compounds prepared by novel routes can befound at the end of the relevant chapter.
AB - The work within this thesis describes developments in platinum catalysedhydrometallation for the synthesis of a range of diverse metalloid scaffolds.Chapter 1 contains a discussion of the application of organometalloid scaffoldsin modern organic chemistry, as well as the widespread application of platinumcomplexes in the synthesis of said scaffolds. Notable developments in the fieldare summarised and the generally accepted mechanisms through which thesereactions proceed are discussed.Chapter 2 examines the limitations of previous platinum complexes in catalysingselective hydrosilylations and the reasons for these limitations, as well asdiscussing the approaches to, and applications of, allylic amines in organicchemistry. The development of a PtCl2Xantphos catalyst to selectively carry outthe hydrosilylation of propargylic amines and their derivatives is detailed as wellas an investigation of the substrate scope. The synthetic utility of the products isinvestigated resulting in the development of a remarkably mild aziridinationprocedure.Chapter 3 builds on the previous aziridination procedure, demonstrating theapplicability of the same sequence to access a range of diverse oxetanes by ahydrosilylation/cyclisation sequence. Previous approaches to oxetanes arediscussed, as well as the utility of the scaffold in modern organic and medicinalchemistry. Attempts to expand the methodology to the synthesis of otherheterocycles is also discussed.Chapter 4 details the study of platinum complexes in the context ofhydrostannylation chemistry. Previous approaches to the scaffold are discussed,as well as the surprising lack of platinum-based catalyst systems. The effect ofligand denticity on stereoselectivity is reported, with a ligand controlledstereodivergency reported. Using a PtCl2(XPhos)2 catalyst system, a range ofdiverse organotin scaffolds are synthesized, and the benefits and limitations ofthe system in comparison to previous catalysts is discussed. A telescoped hydrometallation/cross-coupling sequence is developed to minimize the need tohandle relatively unstable and toxic stannylated intermediates.Chapter 5 explores the application of platinum complexes bearing both NHC andphosphine ligands as hydrosilylation catalysts. The synthesis of a broad range ofimidazolium salts is presented, alongside the synthesis of several platinumcomplexes via an organosilver intermediate. The efficacy of the complexestowards hydrosilylation is evaluated, and their poor performance rationalized inthe context of similar complexes employed in the literature.Chapter 6 provides overall conclusions from the work presented as well as adiscussion of further avenues of study.Chapter 7 provides bibliographic data for the thesis. Relevant characterisationdata for novel compounds or compounds prepared by novel routes can befound at the end of the relevant chapter.
KW - Platinum
KW - Catalysis
KW - Hydrometallation
KW - Silicon
KW - Tin
KW - Cross-coupling
KW - Heterocycles
U2 - 10.17635/lancaster/thesis/2397
DO - 10.17635/lancaster/thesis/2397
M3 - Doctoral Thesis
PB - Lancaster University
ER -