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Iridium–catalyzed asymmetric isomerization of primary allylic alcohols

Defense Thèse de doctorat : Univ. Genève, 2011 - Sc. 4354 - 2011/10/17
Abstract The enantioselective isomerization of primary allylic alcohols into aldehydes is still an underdeveloped process. From the observation that the cationic iridium Crabtree hydrogenation catalyst may perform unexpected isomerization for particular substrates, we developed a protocol to obtain exclusive isomerization of a broad scope of primary allylic alcohols into aldehydes under very mild conditions. The BArF anion provided enhanced stability of the precatalyst and improved catalytic performance. We identified crucial electronic features responsible for the catalytic activity: any variation from the original structure of the Crabtree catalyst, which combines a trialkyl phosphine with a sp2-hybridized N-donor ligand, led to a complete loss of catalytic activity. We synthesized after various types of chiral catalysts for the asymmetric variant of the isomerization reaction. The most successful contain chelating dialkyl-phosphino-alkyl-oxazoline ligands, reaching unprecedented levels of enantioselectivity (up to > 99%) in the case of E–configured allylic alcohols. An intermolecular dihydride mechanism was proposed.
URN: urn:nbn:ch:unige-174084
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MANTILLI, Luca. Iridium–catalyzed asymmetric isomerization of primary allylic alcohols. Université de Genève. Thèse, 2011. https://archive-ouverte.unige.ch/unige:17408

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Deposited on : 2011-11-15

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