Bidentate Chiral Bis(imidazolium)-Based Halogen-Bond Donors: Synthesis and Applications in Enantioselective Recognition and Catalysis

Revannath L. Sutar, Elric Engelage, Raphael Stoll, Stefan M. Huber

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

Even though halogen bonding—the noncovalent interaction between electrophilic halogen substituents and Lewis bases—has now been established in molecular recognition and catalysis, its use in enantioselective processes is still very rarely explored. Herein, we present the synthesis of chiral bidentate halogen-bond donors based on two iodoimidazolium units with rigidly attached chiral sidearms. With these Lewis acids, chiral recognition of a racemic diamine is achieved in NMR studies. DFT calculations support a 1:1 interaction of the halogen-bond donor with both enantiomers and indicate that the chiral recognition is based on a different spatial orientation of the Lewis bases in the halogen-bonded complexes. In addition, moderate enantioselectivity is achieved in a Mukaiyama aldol reaction with a preorganized variant of the chiral halogen-bond donor. This represents the first case in which asymmetric induction was realized with a pure halogen-bond donor lacking any additional active functional groups.

Original languageEnglish
Pages (from-to)6806-6810
Number of pages5
JournalAngewandte Chemie - International Edition
Volume59
Issue number17
DOIs
StatePublished - 20 Apr 2020
Externally publishedYes

Keywords

  • chiral recognition
  • enantioselectivity
  • halogen bonding
  • haloimidazolium salts
  • organocatalysis

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry

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