Silver‐Catalyzed Enantioselective Sulfimidation Mediated by Hydrogen Bonding Interactions

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Abstract
An enantioselective sulfimidation of 3‐thiosubstituted 2‐quinolones and 2‐pyridones was achieved with a stoichiometric nitrene source (PhI=NNs) and a silver‐based catalyst system. Key to the success of the reaction is the use of a chiral phenanthroline ligand with a hydrogen bonding site. The enantioselectivity does not depend on the size of the two substituents at the sulfur atom but only on the binding properties of the heterocyclic lactams. A total of 21 chiral sulfimides were obtained in high yields (44–99 %) and with significant enantiomeric excess (70–99 % ee). The sulfimidation proceeds with high site‐selectivity and can also be employed for the kinetic resolution of chiral sulfoxides. Mechanistic evidence suggests the intermediacy of a heteroleptic silver complex, in which the silver atom is bound to one molecule of the chiral ligand and one molecule of an achiral 1,10‐phenanthroline. Support for the suggested reaction course was obtained by ESI mass spectrometry, DFT calculations, and a Hammett analysis.
Funding Information
  • Deutsche Forschungsgemeinschaft (Ba 1372/17-2)
  • Alexander von Humboldt-Stiftung

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