The site‐selective C−H oxidation of unactivated positions in aliphatic ammonium chains poses a tremendous synthetic challenge, for which a solution has not yet been found. Here, we report the preferential oxidation of the strongly deactivated C3/C4 positions of aliphatic ammonium substrates by employing a novel supramolecular catalyst. This chimeric catalyst was synthesized by linking the well‐explored catalytic moiety Fe(pdp) to an alkyl ammonium binding molecular tweezer. The results highlight the vast potential of overriding the intrinsic reactivity in chemical reactions by guiding catalysis using supramolecular host structures that enable a precise orientation of the substrates.
The site‐selective C−H oxygenation of alkyl chains as well as deactivated positions remains a great challenge for chemists. Here, we report the synthesis and application of four new supramolecular tweezer‐based oxidation catalysts. They consist of the well‐explored M(pdp/mcp) oxidation moiety and a molecular tweezer capable of binding ammonium salts. All catalysts display preferential oxidation of the strongly deactivated C3/C4 positions, however to different degrees. Furthermore, the best performing catalyst Fe(pdp)Twe was explored with an expanded substrate scope. It was demonstrated that the deactivated positions C3/C4 are also preferentially oxidized in these cases.
Selective nanomolar binding of biological polyamines to a novel glycoluril-derived molecular tweezer is reported. The high selectivity over their biosynthetic precursor may be of interest, as elevated polyamine levels are linked to several diseases.
Die positionsselektive C‐H‐Oxidation von nicht aktivierten Stellen in aliphatischen Ammoniumketten stellt eine enorme synthetische Herausforderung dar, für welche bisher keine Lösung gefunden wurde. Wir berichten hier über die bevorzugte Oxidation der stark deaktivierten C3/C4‐Positionen von aliphatischen Ammoniumsubstraten durch den Einsatz eines neuen supramolekularen Katalysators. Dieser chimäre Katalysator wurde durch die Verknüpfung der gut erforschten katalytischen Fe(pdp)‐Einheit an eine Alkylammonium bindende Pinzette hergestellt. Die Ergebnisse verdeutlichen das enorme Potenzial, die intrinsische Reaktivität in chemischen Reaktionen zu überwinden, indem die Katalyse mithilfe supramolekularer Wirtstrukturen, welche eine exakte Orientierung der Substrate ermöglichen, gesteuert wird.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.