2-Aryl-4,5-anti-diphenyloxazolines undergo nucleophilic dearomatising addition to the 2-aryl group when treated with secondary organolithiums at -78 °C in the presence of the deaggregating co-solvent DMPU. Quenching the reaction with methyl iodide gives a highly substituted conjugated diene. Quenching the reaction with a proton source gives a substituted unconjugated 1,4-diene. The stereochemistry of the anti-diphenyl oxazoline controls the diastereoselectivity of the nucleophilic addition; only one diastereoisomeric product is observed. Importantly these conditions allow the dearomatisation of phenyl rings; this moiety has proven resistant to nucleophilic dearomatisation in all but the harshest conditions. This thesis presents the application of this dearomatising reaction. First the scope of this method was explored towards the dearomatisation of phenyl rings with fluorine substituents, as precursors for fluorinated carbasugar analogues. Secondly amino-carbasugar analogues were synthesised. The dearomatisation of a 4-methoxy phenyl ring was used to construct a dearomatised carbocyclic skeleton, which was functionalised through a series of reactions to give fully substituted cyclohexanoid amino-carbasugar analogues. These amino carbasugars were synthesised without the use of protecting groups, in order to do this a number of chemoselective conditions were studied and chemoselective reactions were developed.

Long relegated to the background by the pre-eminence of magnesium-based, stoichiometric Grignard reagents, a distinct chemistry of the heavier alkaline earth metals, calcium, strontium and barium, is only now starting to emerge. As similarities have been drawn between the large, electropositive, redox-inert and d0 alkaline earth Ae2+ dications and the Ln3+ cations of the lanthanide series, a growing group 2-mediated catalytic chemistry has developed over the last decade, including polymerisation reactions, heterofunctionalisation reactions of multiple bonds and some rare examples of dehydrocoupling reactions. Among these catalytic reactions the magnesium- and calcium-catalysed intramolecular hydroamination of aminoalkenes has attracted particular interest. Mechanistic studies have demonstrated many parallels with the lanthanide-mediated catalytic cycle based upon successive σ-bond metathesis and insertion steps. In the first part of this thesis, further investigations into the hydroamination/cyclisation reaction have demonstrated the prominent role of the charge density of the catalytic group 2 cation (M = Mg, Ca, Sr, Ba), the beneficial influence of stabilising spectator ligands, and the importance of the choice of the reactive co-ligand for efficient catalyst initiation. Kinetic analyses of reactions monitored by NMR spectroscopy have given new insight into activation energies, entropic effects, substrate and product inhibition, and kinetic isotope effects, leading to a review of the previously suggested lanthanide-mimetic mechanism. In a second part, this study seeks to address two of the main challenges posed by the intramolecular hydroamination reaction in particular, and heavier alkaline earth-catalysed reactions in general: (i) The need to design new monoanionic spectator ligands capable of stabilising heteroleptic heavier alkaline earth complexes and preventing deleterious Schlenk-type ligand redistribution processes in solution; (ii) The stabilisation of highly reactive heteroleptic group 2 alkyl functionalities for fast, irreversible catalyst initiation and novel reactivity.

Les travaux réalisés dans cette thèse concernent les efforts réalisés pour la synthèse de dérivés chiraux à base d'iode hypervalent analogues de l'acide iodoxybenzoïque, appelé IBX. Ces travaux ont permis de réaliser la synthèses de nouveaux dérivés iodés hypervalents qui ont été utilisés lors de réactions de désaromatisation de phénols énantiosélectives. Outre, les nouveaux dérivés hypervalents iodés synthétisés cette thèse a permis de mettre en avant le caractère problématique de la réaction d'oxydation de l'iode. Une alternative à ce problème a été la mise au point de méthode de génération in situ de dérivés iodés hypervalent permettant de réaliser des réactions de désaromatisation de phénols énantiosélectives. / The work presented in this thesis are about the synthesis of new chiral hypervalent iodine compounds analogues of the iodoxybenzoic acid, called IBX. This work shows an access to new chiral hypervalent iodine compounds which were used in enantioselective dearomatisation of phenols. In addition to the new compounds synthesized, this thesis gives a view of the complexity of the oxidation of iodine compounds. An alternative to this problematic synthetic step is given by the development of in situ generation methodology of hypervalent iodine compounds in order to perform an enantioselectiv variant of the dearomatization reaction.