Tweezer-Based C-H Oxidation Catalysts Overriding the Intrinsic Reactivity of Aliphatic Ammonium Substrates

Melina Knezevic; Konrad Tiefenbacher

doi:10.1002/chem.202203480

Tweezer-Based C-H Oxidation Catalysts Overriding the Intrinsic Reactivity of Aliphatic Ammonium Substrates

Chemistry. 2023 Mar 1;29(13):e202203480. doi: 10.1002/chem.202203480. Epub 2023 Jan 30.

Authors

Melina Knezevic¹, Konrad Tiefenbacher^{1

2}

Affiliations

¹ Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058, Basel, Switzerland.
² Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 24, 4058, Basel, Switzerland.

PMID: 36469523
DOI: 10.1002/chem.202203480

Abstract

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.

Keywords: C−H oxidation; ammonium binding; catalysis; molecular tweezer; supramolecular chemistry.