Conférence du Professeur Jérôme Waser (EPFL)

Titre : Electrophilic Alkynylation of Olefins and Annulation Reactions of Aminocyclopropanes.

Cette conférence sera prononcée en anglais par le professeur Jérôme Waser du laboratoire de catalyse et synthèse organique au sein de l'École polytechnique fédérale de Lausanne (Suisse). Ce dernier sera à Montréal dans le cadre d'une tournée de conférences en Amérique du Nord.

Résumé : The use of organic molecules of increasing complexity is one of the major motors of progress in multiple fields of fundamental and applied science, such as chemical biology, drug discovery or organic materials. To answer these needs, it is crucial to develop new reactions for a fast access into molecular complexity. Our group makes use of the power of catalysis to develop new reactions based
on the exceptional reactivity of electrophilic acetylenes and aminocyclopropanes.

Acetylenes: The triple bond is one of the most versatile functional groups in organic chemistry, material sciences and chemical biology. Most alkyne-transfer reactions have been limited to the nucleophilic addition of acetylides to electrophiles. The development of efficient electrophilic alkynylation methods would give access to structurally completely different acetylenes. Our group has introduced EthynylBenziodoXolone (EBX) hypervalent iodine reagents for direct alkyne-transfer to C=C bonds. The use of a palladium(II) catalyst combined with EBX reagents led to the first intramolecular oxy- and amino- alkynylation of olefins for the synthesis of lactones, lactams, oxazolidinones and imidazolidinones. On the other hand, a palladium(0) catalyst together with alkynyl bromides could be used to access tetrahydrofurans and pyrrolidines starting from alcohols and amines.

Aminocyclopropanes: Activation of cyclopropanes with an amino and a carbonyl group led to exceptional reactivity, both in cyclization and annulation reactions. Selective cyclization on the carbon or nitrogen of indole heterocycles using either copper or Brønsted acid catalysts allowed the synthesis of the alkaloids aspidospermidine and goniomitine. Using Phthalimido-substituted cyclopropanes together with iron or tin catalysts, a highly diastereoselective and enantiospecific [3+2] annulation reaction with enol ethers and carbonyls gave access to multi-substituted cyclopentyl- and tetrahydrofuryl amines, key structural elements of both DNA and bioactive compounds.

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