Spectrometric elucidation of intermediates in asymmetric transfer hydrogenation of ketones catalyzed by complex of ruthenium (II) and isosorbide-based ligand

Abstract

The use of electrospray ionization mass spectrometry for the detection of the intermediate species involved in the ruthenium(II)/β-amino-alcohol derived from isosorbide reduction of ketones to alcohols is described. The formation of active complex of ruthenium (II) for catalyzing the asymmetric transfer hydrogenation of ketones was observed from ¹H-NMR spectra. From high resolution mass spectra, peaks of group of isotopes allow to conform the existence of active species of ruthenium (II) in the presence of isosorbide-based ligand. The recorded high resolution mass spectra when following the typical protocol for the asymmetric transfer hydrogenation of acetophenone confirmed an involvement of the active complex mono-hydride ruthenium in the catalytic circle. As a result, high resolution mass spectra in research on catalytic mechanism can be therefore employed as an alternative tool for studying catalytic mechanism.

Keywords. Asymmetric catalysis, isosorbide, asymmetric transfer hydrogenation.