Catalytic ability of a cationic Ru(II) monochloro complex for the asymmetric hydrogenation of dimethyl itaconate and enamides

Inorg Chem. 2006 Mar 20;45(6):2644-51. doi: 10.1021/ic051032w.

Abstract

The synthesis of two Ru chloro complexes, Ru(III)Cl(3)(bpea), 1, and cis-fac-Delta-[Ru(II)Cl{(R)-(bpea)}{(S)-(BINAP)}](BF(4)), cis-fac-Delta-(R)-(S)-2, (bpea = N,N-bis(2-pyridylmethyl)ethylamine; (S)-BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl), is described. Complex 2 is characterized in solution through UV-vis, cyclic voltammetry (CV), and 1D and 2D NMR spectroscopy. X-ray diffraction analysis indicates that in the solid state it possesses the same structure as in solution, as expected for a low-spin d(6) Ru(II)-type complex. The molecular structure of cis-fac-Delta-(R)-(S)-2, consists of a nonsymmetric complex, where the Ru metal center has a significantly distorted octahedral-type coordination because of the bulkiness of the (S)-BINAP ligand. cis-fac-Delta-(R)-(S)-2 has a remarkable catalytic performance at P = 6.8 atm of H2 and T = 70 degrees C toward the hydrogenation of prochiral double bonds both from efficiency and from stereoselectivity viewpoints. As an example, prochiral olefins of technological interest such as dimethyl itaconate, methyl 2-acetamidoacrylate or methyl 2-acetamidocinnamate are catalytically hydrogenated by cis-fac-Delta-(R)-(S)-2, with conversions higher than 99.9% and ee > 99. Furthermore, cis-fac-Delta-(R)-(S)-2, also catalyzes the selective hydrogenation of beta-keto esters, although the reaction rates are lower than those found with the former substrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / chemistry*
  • Catalysis
  • Cations
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis*
  • Organometallic Compounds / chemistry
  • Oxidation-Reduction
  • Ruthenium Compounds / chemistry*
  • Stereoisomerism
  • Succinates / chemistry*

Substances

  • Amides
  • Cations
  • Organometallic Compounds
  • Ruthenium Compounds
  • Succinates
  • dimethyl itaconate
  • itaconic acid
  • ruthenium chloride