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Medientyp:
E-Book;
Hochschulschrift
Titel:
Synthesis of enantiomerically pure helical aromatics such as NHC ligands and their use in asymmetric catalysis
Weitere Titel:
Übersetzung des Haupttitels: Die Synthese von enantiomerenreinen helikalen Aromaten wie NHC Liganden und deren Anwendung in asymmetrischer Katalyse
Hochschulschrift:
Dissertation, Universität Potsdam, 2018
Anmerkungen:
Beschreibung:
Various ways of preparing enantiomerically pure 2-amino[6]helicene derivatives were explored. Ni(0) mediated cyclotrimerization of enantiopure triynes provided (M)- and (P)-7,8-bis(p-tolyl)hexahelicene-2-amine in >99% ee as well as its benzoderivative in >99% ee. The stereocontrol was found to be inefficient for a 2- aminobenzo[6]helicene congener with an embedded five-membered ring. Helically chiral imidazolium salts bearing one or two helicene moieties have been synthesized and applied in enantioselective [2+2+2] cyclotrimerization catalyzed by an in situ formed Ni(0)-NHC complex. The synthesis of the first helically chiral Pd- and Ru-NHC complexes and their application in enantioselective catalysis was demonstrated. The latter shows promising results in enantioselective olefin metathesis reactions. A mechanistic proposal for asymmetric ring closing metathesis is provided.