Synthesis of iridium and rhodium complexes with new chiral phosphine-NHC ligands based on 1,1'-binaphthyl framework and their application in asymmetric hydrogenation

Dalton Trans. 2013 Oct 7;42(37):13599-606. doi: 10.1039/c3dt51141c. Epub 2013 Jul 30.

Abstract

The first series of chiral phosphine-imidazole carbene ligands based on a 1,1'-binaphthyl framework were synthesized from (R)-2-amine-2'-(diphenylphosphino)-1,1'-binaphthyl (1) in a four-step pathway. After deprotonation of these phosphine-imidazolium salts with LiO(t)Bu, and subsequent complexation with [Ir(COD)Cl]2 and anion exchange with NaBArF, phosphine-carbene chelated iridium complexes (R)-6a and (R)-6b were obtained. Their structures have been characterized by NMR and X-ray diffraction analysis. The NHC-phosphine rhodium complex (R)-6c has been also obtained by a similar synthetic method. These iridium complexes have been applied to catalyze the asymmetric hydrogenation of alkenes to give the corresponding products in moderate to excellent conversion (up to 99%) and moderate enantioselectivities under mild conditions (up to 61% ee).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Heterocyclic Compounds / chemistry*
  • Hydrogenation
  • Iridium / chemistry*
  • Ligands
  • Models, Molecular
  • Molecular Structure
  • Naphthalenes / chemistry*
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Phosphines / chemistry*
  • Rhodium / chemistry*

Substances

  • Heterocyclic Compounds
  • Ligands
  • Naphthalenes
  • Organometallic Compounds
  • Phosphines
  • Iridium
  • Rhodium
  • phosphine
  • 1,1'-binaphthyl