Thèses (M.Sc.)--Université de Sherbrooke (Canada), 1997. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Thèses (M.Sc.)--Université de Sherbrooke (Canada), 2003. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Universiẗat, Diss., 2004--Kiel.

The object of study of this thesis lies on the optimisation of the oxidative radical cyclisation methodology for the preferential formation of gamma-lactones from unsaturated alkyl malonate derivatives. <strong>Chapter 1</strong> introduces the concept of free-radical cyclisation; more extensive explanations are given for the intramolecular oxidative radical cyclisation using manganese(III) and copper(II) salts as oxidants. An overview of the contribution of the Burton group in the field is given, in which both the applicability and the limitations of the transformation are showcased. <strong>Chapter 2</strong> is concerned with the synthesis of the ethisolide family of natural products and one non-natural analogue, in which the oxidative radical cyclisation is key for the construction of the bis-gamme-lactone moiety present in such natural products. The initial limitations of the methodology allowed for the discovery of new conditions for the formation of chloro monocyclic systems and for the development of copper-free oxidative cyclisation conditions for gamma-lactone formation. <strong>Chapter 3</strong> reports the developments on the metal-free oxidative radical cyclisation. Bicyclic gamma-lactones were synthesised from all-carbon alkyl malonate derivatives through anodic oxidation via constant current electrolysis. The development of a novel ionic oxidative cyclisation is also discussed. <strong>Chapter 4</strong> describes our efforts towards the formation of both fused and spiro gamma-lactam-beta-lactone molecules, as potential analogues to proteasome inhibitors, from either gamma-lactam-gamma-lactones or exo-gamma-lactams precursors, previously synthesised through oxidative radical cyclisation. Full experimental details, NMR spectra for the natural products and for the non-natural analogue, and a comparison between the obtained and the previously reported NMR data are also provided.

This thesis is concerned with the development of cyclisation strategies that allow entry to polycyclic heterocycles and medium sized ring systems. Radical additions to pyridines are developed and methodologies explore the differences between the homolysis of C-Br and C-I bonds. Mechanisms are described for the unexpected ipso additions to the pyridines. Work towards the synthesis of the stegnans and dimethylgomisin illustrates the attempts to utilise the ipso addition to form medium sized ring systems. A new method of synthesising these medium sized ring systems is discussed. Progress towards a general methodology is described and shows the opportunities for which it could be utilised. A literature review of the synthesis of heterocycles via radical cyclisations is presented.

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Application of radical reactions in the organic synthesis for the formation of carbon-carbon bond has dramatically increased over the last fifteen years by virtue of their high degree of chemo-, regio- and stereoselectivity. The present thesis entitled "Radical Cyclisation based Approaches to 9-pupukeanone and Lignan Precursors" describes the application of radical reactions in the synthesis of isotwistane carbon framework present in pupukeananes, and b-arylmethylbutyrolactones, established precursors of various types of lignans. For convenience, the results are presented in two chapters, & ( I ) Radical annulation approach to chiral analogues of 9-pupukeanones; (2) Synthesis of (+-)-enterolactone and lignan precursors; and an appendix entitled 'Chiral synthons from (R)- carvone'. In each Chapter the compounds are sequentially numbered (bold and double underlined), and references are marked sequentially as superscripts and listed at the end of the Chapter. All the figures were obtained by direct xerox of the originaltNMR and muss spectra, and in some of them uninformative areas have been cut to save the space.