Iridium phosphite-oxazoline catalysts for the highly enantioselective hydrogenation of terminal alkenes

J Am Chem Soc. 2009 Sep 2;131(34):12344-53. doi: 10.1021/ja904152r.

Abstract

A modular library of readily available phosphite-oxazoline ligands (L1-L16a-f) has been successfully applied for the first time in the Ir-catalyzed asymmetric hydrogenation of a broad range of highly unfunctionalized 1,1,-disubstituted terminal alkenes. Enantioselectivities up to >99% and full conversions were obtained in several 1,1-disubstituted alkenes, including substrate classes that have never been asymmetrically hydrogenated before (i.e., 1,1-heteoraryl-alkyl, 1,1-diaryl, trifluoromethyl, etc.). The results indicated that these catalytic systems have high tolerance to the steric and electronic requirements of the substrate and also to the presence of a neighboring polar group. The asymmetric hydrogenations were also performed using propylene carbonate as solvent, which allowed the Ir catalyst to be reused and maintained the excellent enantioselectivities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkenes / chemistry*
  • Catalysis
  • Hydrogenation
  • Iridium / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Organometallic Compounds / chemistry*
  • Oxazoles / chemistry*
  • Phosphites / chemistry*
  • Stereoisomerism
  • Substrate Specificity

Substances

  • Alkenes
  • Organometallic Compounds
  • Oxazoles
  • Phosphites
  • Iridium