Enantioselective Protonation: Hydrophosphinylation of 1,1-Vinyl Azaheterocycle N-Oxides Catalyzed by Chiral Bis(guanidino)iminophosphorane Organosuperbase

Saikat Das, Qiupeng Hu, Azusa Kondoh, Masahiro Terada

Research output: Contribution to journalArticlepeer-review

Abstract

Enantioselective protonation by hydrophosphinylation of diarylphosphine oxides with 2-vinyl azaheterocycle N-oxide derivatives was demonstrated using chiral bis(guanidino)iminophosphorane as the higher-order organosuperbase catalyst. It was confirmed by several control experiments that a chiral weak conjugate acid of the chiral bis(guanidino)iminophosphorane, instead of achiral diarylphosphine oxides, directly functioned as the proton source to afford the corresponding product in a highly enantioselective manner in most cases. Enantioselective protonation by a weak conjugate acid generated from the higher-order organosuperbase would broaden the scope of enantioselective reaction systems because of utilization of a range of less acidic pronucleophiles. This method is highlighted by the valuable synthesis of a series of chiral P,N-ligands for chiral metal complexes through the reduction of phosphine oxide and N-oxide units of the corresponding product without loss of enantiomeric purity.

Original languageEnglish
Pages (from-to)1417-1422
Number of pages6
JournalAngewandte Chemie - International Edition
Volume60
Issue number3
DOIs
Publication statusPublished - 2021 Jan 18

Keywords

  • base catalysis
  • chiral ligands
  • enantioselective protonation
  • hydrophosphinylation
  • organocatalysis

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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