Dynamic kinetic resolution of biaryl atropisomers via peptide-catalyzed asymmetric bromination

Science. 2010 Jun 4;328(5983):1251-5. doi: 10.1126/science.1188403.

Abstract

Despite the widespread use of axially chiral, or atropisomeric, biaryl ligands in modern synthesis and the occurrence of numerous natural products exhibiting axial chirality, few catalytic methods have emerged for the direct asymmetric preparation of this compound class. Here, we present a tripeptide-derived small-molecule catalyst for the dynamic kinetic resolution of racemic biaryl substrates. The reaction proceeds via an atropisomer-selective electrophilic aromatic substitution reaction using simple bromination reagents. The result is an enantioselective synthesis that delivers chiral nonracemic biaryl compounds with excellent optical purity and good isolated chemical yields (in most cases a >95:5 enantiomer ratio and isolated yields of 65 to 87%). A mechanistic model is advanced that accounts for the basis of selectivity observed.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Biphenyl Compounds / chemical synthesis*
  • Biphenyl Compounds / chemistry
  • Bromine / chemistry
  • Catalysis
  • Chemical Phenomena
  • Halogenation*
  • Kinetics
  • Ligands
  • Molecular Structure
  • Oligopeptides / chemistry*
  • Stereoisomerism*
  • Temperature

Substances

  • Biphenyl Compounds
  • Ligands
  • Oligopeptides
  • Bromine