Synthesis of heterodonor ligands and investigation of their catalytic applications

Optically active compounds are very important both in industry and academic field.Asymmetric catalysis is considered to be an ideal method for synthesing optically activecompounds. Especially, asymmetric transfer hydrogenation is one of the most efficient methodsto obtain optically active secondary alcohols from ketones. Furthermore, transfer hydrogenationreaction is very important since the method is simple, environmentally benign and reactionconditions are moderate and it is easy to handle.The chemistry of aminophosphines and phosphinites has also been intensively exploredin recent years. These compounds are extremely attractive as potential ligands since variousstructural modifications are accessible via simple P-O and P-N bond formation. Many modifiedphosphine ligands and a variety of chiral aminophosphine-phosphinite ligands have importantapplications in organomatallic chemistry and catalysis, giving selective catalysts forhydroformylation, hydrosilylation and asymmetric transfer hydrogenation. While much efforthas been devoted to the synthesis of aminophosphines and their metal complexes, similarstudies on the analogous bis(phosphinites) are less extensive even though some of theircomplexes have proved to be efficient catalysts.In the present work, firstly, 3-3'-diamino-2,2'-bipyridine, 3-3'-dihydroxy-2,2'-bipyridine,N,N'-bis[(1S)-1-benzyl-2-hydroxyethyl]etanediamide, N,N'-bis[(1R)-1-ethyl-2-hydroxyethyl]etanediamide, N,N'-bis[(1S)-1-isobuthyl-2-hydroxyethyl]etanediamide and (R )-(-)-N-benzyl-4-hydroxymethyl-3-azahekzan-1-ol were synthesized according to the literature. Then, sevenP(III) type ligands having P-NHR and P-OR framework were obtained by the reaction of thesecompounds with Ph2PCl or Cy2PCl. Treatment of these ligands with [Ru(?6-p-cymene)Cl2]2afforded new Ru(II) complexes which were characterized by spectroscopic methods, such asNMR and IR, and elemental analysis. Finally, the complexes were used as catalyst in transferhydrogenation reaction of ketones. Generally, high conversions and with some complexesenantiomeric excess (ee) up to 80 % were obtained.