Stereoselective C9 carbon-carbon couplings of quinine: synthesis and conformational analysis of new C2-symmetric dimers

J Org Chem. 2008 Sep 19;73(18):7357-60. doi: 10.1021/jo801205n. Epub 2008 Aug 8.

Abstract

An unexpected stereoselective direct dimerization occurred when 9-quinine halide was treated with butyllithium. The reaction of either (9S)- or (9R)-chloroquinine gave the same C2-symmetric dimer with 9R configuration (X-ray structure). A tentative mechanism involving radical recombination is discussed. This highly congested dimer forms two atropisomers, and their reversible interconversion was studied by NMR. Another C2-symmetric (9S)-quinine dimer connected solely by carbon-carbon bonds was obtained by the stereoselective coupling of bis(arylbromomagnesium) derivative with (9S)-chloroquinine.

MeSH terms

  • Carbon / chemistry*
  • Chloroquine / analogs & derivatives
  • Chloroquine / chemistry
  • Crystallography, X-Ray
  • Dimerization
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Conformation
  • Organometallic Compounds / chemistry
  • Quinine / analogs & derivatives
  • Quinine / chemical synthesis*
  • Quinine / chemistry*
  • Stereoisomerism

Substances

  • Organometallic Compounds
  • butyllithium
  • Carbon
  • Chloroquine
  • Quinine