Catch and release’ cascades: a resin-mediated three-component cascade approach to small molecules

The application of a ‘catch and release’ approach to palladium-catalysed multi-component cascade reactions leads to diverse libraries of pharmacologically interesting small molecules in high yield and with excellent purity

Catalysed Reactions

Abstract Not Provided

Synthetic Retinoids

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

Inter- and intramolecular Diels-Alder/retro-Diels-Alder reactions of 4-silylated oxazoles

4-Silylated oxazoles have been shown to undergo inter- and intramolecular Diels-Alder/retro-Diels-Alder reactions with electron-poor alkynes to generate polysubstituted furans. The ease of synthesis of the requisite oxazoles by the rhodium-catalysed condensation of nitriles with silylated diazoacetate greatly increases the scope of this reaction

X=Y–ZH compounds as potential 1,3-dipoles. Part 64: Synthesis of highly substituted conformationally restricted and spiro nitropyrrolidines via Ag(I) catalysed azomethine ylide cycloadditions

1,3-Dipolar reactions of imines of both acyclic and cyclic α-amino esters with a range of nitroolefins using a combination of AgOAc or Ag2O with NEt3 are described. In most cases the reactions were highly regio- and stereospecific and endo-cycloadducts were obtained in good yield. However, in a few cases the initially formed cycloadducts underwent base catalysed epimerisation. The stereochemistry of the cycloadducts was assigned from NOE data and established unequivocally in several cases by X-ray crystallography

Gold-Catalysed Reactions

In recent years, there have been three significant pieces of research which helped propel gold catalysis research into the forefront: the discoveries that gold/silica can catalyse the hydrogenation of pentene, that gold on carbon can be used in the hydrochlorination of acetylene and that deposition-precipitation (DP) methods can be used to prepare nanogold on titania capable of enabling the oxidation of CO at very low temperatures. The synthesis of small gold particles, their characterisation and peculiar properties are considered together with their behaviour as heterogeneous catalysts for a variety of reactions. Some of the issues concerning the practical application of gold catalysts are also discussed

The Reactions of Gaseous 1,1,1-Trichloroethane With Solid Aluminium (III) Chloride

Aluminium (III) chloride catalysed dehydrochlorination of 1,1,1-trichloroethane is industrially important, as it is considered to be one of the first steps in the degradation of 1,1,1-trichloroethane based solvents used in the large scale vapour degreasing of aluminium. The degradation and fouling observed has been attributed to aluminium (III) chloride catalysed dehydrochlorination of the solvent, followed by aluminium (III) chloride catalysed oligomerisation of the dehydrochlorinated product. There is evidence that heterogeneous phenomena are of importance in these reactions, and in this work the reactions of gaseous 1,1,1-trichloroethane and 1,1-dichloroethene with solid aluminium (III) chloride were studied

Synthesis of substituted benzooxaborinin-1-ols via palladium-catalysed cyclisation of alkenyl- and alkynyl-boronic acids

Two new palladium-catalysed reactions have been developed for the synthesis of stable 4-substituted benzooxaborinin-1-ols. A palladium-catalysed cyclisation of ortho-alkenylbenzene boronic acids can be used to access 4-chlorobenzooxaborinin-1-ols via a Wacker-type oxidation and chlorination. Alternatively, ortho-alkynylbenzene boronic acids undergo a palladium-catalysed oxyallylation reaction to provide 4-allylbenzooxaborinin-1-ols

The development of gold-catalysed reactions

This thesis describes the research carried out in the development of novel homogeneous gold(I)-catalysed reactions. It is written in such a format as to describe chronologically the process in which the study and our understanding evolved. Chapter one provides an introduction to homogeneous gold catalysis and in particular the development and reactivity of gold(I) catalysts as powerful activators of unsaturated carbon-carbon species towards nucleophilic attack. Chapter two describes our initial work in this area and how we were able to show that gold(I) can catalyse the intramolecular rearrangements of cyclopropenes with ester functionalities. Chapter three presents the intermolecular addition of alcohol to 3,3-dialkyl and aryl cyclopropenes catalysed by gold(I). Chapter four describes how we were able to utilise our knowledge of gold(I)-catalysed reactions with cyclopropenes to completely switch the regiochemistry of gold(I)-catalysed hydroalkoxylation of allenes from producing primary alkyl allylic ethers to tertiary alkyl allylic ethers. We were also able to show that by trapping the vinyl gold intermediate we could further functionalise the tertiary allylic ether. Chapter five describes the results of the addition of furan to cyclopropenes catalysed by gold(I) to produce functionalised conjugated trienes. Chapter six presents initial work into the gold(I) catalysed addition of indoles to cyclopropenes. Also described in this chapter are the attempted reactions with a variety of alternative nucleophiles

Metal-free syn-dioxygenation of alkenes

Reactions employing inexpensive reagents from sustainable sources and with low toxicity are becoming increasingly desirable from an academic and industrial perspective. A fascinating example of a synthetic transformation that requires development of alternative procedures is the osmium catalysed dihydroxylation. Recently there has been considerable interest in achieving this reaction through metal-free procedures. This review describes the methods available for metal-free syn-dioxygenation of alkenes