On the synthesis of N-O bonds in novel heterocyclic systems

Hatherley, Jessica 2012. On the synthesis of N-O bonds in novel heterocyclic systems. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The origins of these investigations are in the pursuit of heterocycles containing an N-O bond. This project as a whole focusses on developing earlier chance observations made by previous members of the Knight Research Group. Chapter 2 focusses on the synthesis of isoxazoles: 5-membered aromatic rings containing a nitrogen to oxygen bond. The origin of this project was the unexpected observation of a small percentage of isoxazole products in the Group’s earlier synthesis of isoxazolines, which were thought to be the oxidation products arising from using silver nitrate as a catalyst for those cyclisations. It has now been found that by using an excess of silver nitrate, isoxazoles can be selectively formed from the same hydroxylamine precursors. Chapter 3 centres on the viability of obtaining unusual 6-endo-trig products from the iodocyclisation of unsaturated tert-butyl carbonates. This Chapter is connected to the theme of N-O chemistry, as the tert-butyl carbonate starting materials were the unexpected products of a synthesis that had been designed to form hydroxylamines. The initial discovery of these unexpected 6-endo products on iodocyclisation was expanded upon to produce a series of cyclic carbonates with a procedure optimised to maximise the yield of this desired structural isomer. Chapter 4 concentrates on building saturated N-O rings onto existing cyclic systems, including transannular cyclisations - investigating previous reports of rearrangement of N and O during cyclisation and working towards a synthesis of the core-structure of the natural product Histrionicotoxin. These schemes prove the utility of this acid-catalysed hydroamination methodology in building heterocycles and the chiral products that can be gleaned from them. For the most part, this project has been concerned with methodology - solving problems and optimising key-step procedures - which can be applied to complex target molecules.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Date of First Compliant Deposit:	5 September 2023
Last Modified:	05 Sep 2023 08:44
URI:	https://orca.cardiff.ac.uk/id/eprint/42965

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