This thesis describes work on aqueous dynamic combinatorial libraries (DCLs) with inbuilt donor-acceptor recognition units, aiming at catenane assembly using a dynamic combinatorial approach. In Chapter 1, the general background on donor-acceptor interactions, examples of donor-acceptor catenanes and related supramolecular systems, as well as the principle of DCC and examples of disulfide DCLs are described. Chapter 2 presents the initial studies on the exploitation of donor-acceptor interactions in aqueous DCLs containing separate donor and acceptor building blocks. Chapter 3 deals with DCLs consist of both the donor and acceptor building blocks. The discovery, amplification, characterisation and binding studies of the first [2]catenane assembled from such a library are also described. The characterisation, conformational studies and binding behaviour of an isomeric [2]catenane are presented in Chapter 4. Chapter 5 continues to explore the DCL behaviour of a number of isomeric donor building blocks in relation to their abilities in catenane formation. New [2]catenanes, either with an unexpected stoichiometry or composed of different kinds of donor and acceptor units, are discussed. Experimental procedures and supplementary information are provided in Chapter 6 and Appendix.

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Forty-five 3-aryl benzo-1,2,4-thiadiazine derivatives have been prepared and twenty-two derivatives characterised by X-ray diffraction. Their solid-state molecular structures reveal low energy pathways for deformation through (i) rotation of the aryl group; (ii) folding of the heterocycle about the transannular S^….N vector. This largely qualitative assessment has been supported by <i>ab initio</i> DFT (B3LYP/6-31G) calculations. Improvements to the published syntheses the related 3-aryl benzo-1,2,4-thiadiazine 1-chlorides have increased yields and selectivity. A new route to these salts has been developed utilising SOC1₂ as the source of S^IV which exhibits lower degrees of chlorination of the benzo-fused ring. A total of six benzo-substituted 3-aryl benzo-1,2,4-thiadiazine 1-chlorides have been prepared of which five were characterised by X-ray diffraction. Conformational polymorphism was identified in 1,6,7-trichloro-5-chloromethyl-8-methyl-3-phenyl-benzo-1,2,4-thiadiazine and the energy barrier to interconversion between polymorphs probed by <i>ab initio</i> DFT calculations. Electrochemical studies on the 1-chloride salts reveal a good correlation between the E_1/2 for their 1<i>e</i>^- reduction and their LUMO energies from <i>ab initio</i> DFT (B3LYP/6-31G) calculations. Solution state EPR studies have been performed on the radicals formed by oxidation of 3-aryl-benzo-1,2,4-thiadiazines <i>or</i> reduction of 3-aryl-benzo-1,2,4-thiadiazine 1-chlorides respectively. Correlation between the experimental heterocyclic spin density estimated from the McConnell relationship and the calculated spin density from semi-empirical (AM1, PM3, PM5) were found to be poor. 3-pyrid-2-yl benzo-1,2,4-thiadiazine (LH) has been shown to react with CuCl₂.2H₂O and anhydrous CoCl₂ to form the chelate complexes CuCl₂(LH), CuCl₂(LH)₂ and CoCl₂(LH)₂ which have been characterised by X-ray diffraction.

Some of the best-performing organic field-effect transistors (OFETs) use thiophene-based semiconductors such as poly(3-hexylthiophene) (P3HT) and poly(9,9-dioctylfluorene-<i>alt­</i>-bithiophene) (F8T2). In recent years much interest has been directed to dithieno[3,2-<i>b</i>:2’,3’-<i>d</i>]thiophene (DTT) as a unit in semiconducting organic materials. However, these derivatives were also largely insoluble. Because insoluble organic materials do not present a practical alternative to widely-used inorganic semiconductors like silicon, there is a lot of interest in creating organic semiconductors that can be processed from solution. Hence, this thesis is focused on the preparation of soluble DTTs as semiconductors for OFETs. As DTT is relatively unreactive, the best approach to soluble derivatives is shown to be to incorporate solubilising groups as the DTT skeleton is built. The synthetic route applied, based on Friedel-Crafts acylations followed by annelations with ethyl 2-mercaptoacetate, allows the formation of a wide range of 3- and 3,5-substituted DTTs. The route is also flexible in that the 3,5-disubstitued DTTs may be symmetric or asymmetric. The synthetic method also features a one-pot conversion of substituted DTT-2,6-diesters into 2,6-dibromoDTTs, which can then be reacted under palladium-catalysed cross-coupling conditions to form new conjugated macromolecules and polymers. This bromo-decarboxylation process improves on the classical route by removing the need for toxic quinoline in the decarboxylation of DTT-2,6-dicarboxylic acids. The new substituted DTT derivatives were incorporated into soluble conjugated homo- and copolymers. Some of the new polymers were good hole-transporters, with mobilities up to 10^-4 cm² V^-1s^-1 being measured in OFETs. This value is only one order of magnitude lower than has been reported for commercial F8T2, showing that these materials have good potential for optoelectronic applications.

Discodermolide (1) and dictyostatin (211) are polyketide metabolites, isolated from marine sponges, which display potent activity as antimitotic agents with a similar mechanism of action to Taxol^® (paclitaxel), by stabilising microtubules and promoting the polymerisation of tubulin. They represent important natural product leads for the development of new anti-cancer agents, particular for the treatment of multidrug resistant tumours. The first part of this thesis describes the development of a practical second generation synthesis of discodermolide. The identical stereochemical triad, repeated three times in the structure of discodermolide (C₂-C₅, C₁₀-C₁₂, C₁₈-C₂₀), allowed the construction of key fragments 80 (C₁-C₅), 122 (C₉-C₁₆) and 53 (C₁₇-C₂₄) from a common precursor, 1,3-diol 82. The subsequent fragment couplings and the efficient elaborations to the natural product are also detailed. The synthesis of (+)-discodermolide was completed in 25 steps and 7.8% overall yield from methyl (<i>S</i>)-3-hydroxy-2-methyl propionate. Notably, the route relies solely on substrate control to configure all the remaining stereocentres. The methodology developed for the synthesis of discodermolide was exploited for the synthesis of novel analogues, 185 and 185, with the aim of varying the hydrogen bonding/donor acceptor sites in the C₁₄-C₁₈ region of the linear polyketide backbone. The second part of this thesis deals with the structural determination and total synthesis of the novel 22-membered macrolide, dictyostatin (211). The relative stereochemistry in 266 was determined based on a combination of extensive high field NMR studies, including <i>J</i>-based configuration analysis, and molecular modelling. Confirmation of this proposal was sought by total synthesis of the proposed stereostructure 266. The final chapter describes the synthesis of the three key fragments, 271(C₈-C₁₇), <i>ent-</i>230 (C₁-C₇) and 270 (C₁₈-C₂₆), and the studies towards their coupling.

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Chapter one is split into three sections, providing general overviews of synthetic retinoids and their biology, Pd-catalysed C-C bond forming reactions and transition metal-catalysed borylation of aromatic and vinylic C-H bonds, respectively. Chapter two details the application of sequential Ir-catalysed aromatic C-H borylations, Pd-catalysed C-C bond forming reactions and Rh-catalysed vinylic C-H borylations for the stereo-controlled synthesis of stilbene-based TTNPB retinoids. Chapter three details the application of Ir-catalysed aromatic C-H borylations, Sonogashira cross-couplings and Suzuki-Miyaura cross-couplings for the synthesis of tolan-, and biaryl-based retinoids. Chapter four details the development and applications of new RhI catalyst precursors for the dehydrogenative borylation of unactivated olefins. The dehydrogenative borylation reactions were utilised in one-pot, single solvent syntheses of 2-arylindenes from indene and arylhalides through C-H borylation and subsequent Suzuki-Miyaura cross-couplings.

The work described in this thesis is concerned with the synthesis, isolation and characterisation of macrocyclic oligomers ("cyclomers") found in semi-crystalline poly(aryl ether ketone)s. A wide range of cyclomers were obtained in good yield (up to 92%) under pseudo-high dilution by nucleophilic condensation and their cyclic nature was confirmed by a range of analytical techniques. Selected macrocycles were used to produce polymers by ring-opening polymerisation in the melt. It was also shown that during a typical high-temperature synthesis of a poly(aryl ether ketone). such cyclic oligomers are incorporated into the polymer chain. Polymers with a high macrocyclic content were synthesised by high temperature polycondensation at low monomer concentration. These materials were used to assess the influence of macrocycles on polymer viscosity in the melt.

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