Organocatalytic Approaches to Asymmetric Oxidation: Epoxidation of α-Branched 
Enals and α-Benzoyloxylation of Carbonyl Compounds

Lifchits, Olga

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Organocatalytic Approaches to Asymmetric Oxidation: Epoxidation of α-Branched Enals and α-Benzoyloxylation of Carbonyl Compounds

Lifchits, O. (2012). Organocatalytic Approaches to Asymmetric Oxidation: Epoxidation of α-Branched Enals and α-Benzoyloxylation of Carbonyl Compounds. PhD Thesis, Universität zu Köln, Köln.

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Datensatz-Permalink: https://hdl.handle.net/11858/00-001M-0000-000E-F25F-7 Versions-Permalink: https://hdl.handle.net/21.11116/0000-000D-6CA7-E

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Urheber:
Lifchits, Olga¹, Autor

Affiliations:
1Research Department List, Max-Planck-Institut für Kohlenforschung, Max Planck Society, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, DE, ou_1445585

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Zusammenfassung: This work describes the development of enantioselective oxidation reactions of carbonyl compounds using covalent organocatalysis. In the first part, asymmetric epoxidation of α-branched α,β-unsaturated aldehydes with aqueous hydrogen peroxide is presented. An exceptionally synergistic combination of a primary cinchona alkaloid-derived amine and a chiral BINOL-derived phosphoric acid was found to promote the reaction with excellent enantiocontrol for a wide variety of α,β-disubstituted and α-monosubstituted enals. Conformational analysis of catalytically relevant intermediates using NMR and computational techniques enabled the rationalization of the absolute stereochemistry of products. The second part of this thesis describes a highly efficient direct catalytic asymmetric α-benzoyloxylation of cyclic ketones. The same primary amine paired with an inorganic acid was found to be an effective catalyst for a wide range of substrates. The methodology was applied to the first asymmetric synthesis of (+)-2β,4-dihydroxy-1,8-cineole, a predicted terpenoid metabolite in mammals. Preliminary investigations on the α-benzoyloxylation of α-branched aldehydes and α-branched enals using this catalytic system demonstrated significant potential of the method for the enantioselective formation of oxygenated quaternary stereocenters.