Asymmetric synthesis 1,2,3-triazoles utilising the copper-catalysed azide-alkyne cycloaddition

Brittain, William David George (2018). Asymmetric synthesis 1,2,3-triazoles utilising the copper-catalysed azide-alkyne cycloaddition. University of Birmingham. Ph.D.

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Abstract

The copper-catalysed azide-alkyne cycloaddition (CuAAC) is a highly efficient reaction and is the cornerstone of “click” chemistry. However, unlike many common metal-mediated transformations asymmetric CuAAC variants are relatively sparse. This thesis details asymmetric “click” reactions with Chapter 1 introducing the CuAAC and the asymmetric variants already present in the literature. Chapter 2 outlines research demonstrating the first example of kinetic resolution of an alkyne via a CuAAC reaction. Selectivity factors of up to 22.1 ± 0.5 were obtained and triazoles and alkynes were obtained in ≤ 80% enantiomeric excess (ee). This chapter also contains a study on the simultaneous kinetic resolution of azides and alkynes; azides were obtained in >30% \(e\)\(e\), alkynes in >40% \(e\)\(e\) and a triazolic diastereomeric product was obtained in up to 90% \(e\)\(e\). In Chapter 3 the Bull-James three-component boronic acid assembly is successfully employed for the kinetic resolution of primary amine alkynes with selectivity factors of up to 4.1 obtained. The principle behind the assembly is also elaborated upon in this chapter leading to its use in both dynamic combinatorial chemistry and as a pedagogical tool. Chapter 4 details work on atropisomerism in triazolic systems. A series of novel triazoles, iodotriazoles and triazolium salts were successfully synthesised and their atropisomeric stability probed. Chapter 5 presents feasibility studies towards the asymmetric synthesis of 5,5’-bis(triazoles) and ruthenium olefin metathesis catalysts in the formation of 1,5-triazoles.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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