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Mechanistic investigations and development of Rh(II)-catalyzed [3+6+3+6] macrocyclization reactions

Defense Thèse de doctorat : Univ. Genève, 2016 - Sc. 4928 - 2016/03/11
Abstract In 2010 the group of Professor Jérôme Lacour disclosed a new [3+6+3+6] reactivity leading to the formation of macrocyclic structures, closely related to 18C6 crown ethers. This reaction was achieved using a combination of alpha-diazo-beta-ketoesters reagents, 6-membered cyclic ethers and Rh(II) complexes as catalysts. The project of this PhD thesis was to disclose the kinetic and mechanistic parameters governing the formation of these macrocyclic structures and to optimize the process to readily scale up the reactions with low catalyst loading. These conditions were then applied on nitrogen containing substrates which were challenging at the time, such as morpholines. Moreover, an in-depth analysis of the key reaction parameters will be provided, with a focus on the role of the dirhodium catalysts and the diazo decomposition kinetics. The studies were also dedicated to an extensive analysis of the mechanism generating the macrocyclic structures, with a particular care on the characterization (reactivity and structure) of key oxonium ylide intermediate. Several achiral dirhodium complexes were synthetized, structurally analyzed, and applied in the reaction, showing, for some of them, such as novel Rh2(TCPTCC)4, a better catalytic activity. A scale up process (20 g of diazo) with a catalyst loading as low as 0.001 mol% was then generalized to increase the scope of the reaction. Challenging substrates such as protected morpholines were successfully used, generating aza-polyether macrocycles.
Keywords Macrocyclic structuresAcceptor-acceptor diazoRhodium catalystKinetics studiesOxonium ylideScale-up reactionLow catalyst loadingAza-polyether macrocycles.
URN: urn:nbn:ch:unige-848337
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Research group Groupe Lacour
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POGGIALI, Daniele. Mechanistic investigations and development of Rh(II)-catalyzed [3+6+3+6] macrocyclization reactions. Université de Genève. Thèse, 2016. doi: 10.13097/archive-ouverte/unige:84833 https://archive-ouverte.unige.ch/unige:84833

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Deposited on : 2016-06-29

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