Preparation and use of a chiral amine ruthenium hydrogenation catalyst supported on mesoporous silica

Abstract

Abstract We report the synthesis and use of dichloro-( S )-6,6′-dimethyl-2,2′-diaminobiphenyl-ruthenium complex (( S )-MAB-Ru), an air-stable, highly active catalyst for the hydrogenation of α,β-unsaturated carboxylic acids at 25 °C and 4.85 atm hydrogen. The homogeneous hydrogenations of itaconic acid and α-acetamidocinnamic acid had yields above 97% in each case, and the enantiomeric excesses (e.e.) were 80 and 69.8% to the ( R )-products, respectively. When we used ( S )-MAB-Ru chemically bound to MCM-41, a mesoporous SiO 2 , the conversion of both acids was complete and both e.e. were practically 97%. The solid-bound catalyst was successfully reutilized in the hydrogenation of itaconic acid and the drop in asymmetric induction was only 3% after three runs. The fact that complexes containing chiral amine ligands provide such high yields and e.e. opens a potentially important area of research in the design of industrially relevant catalysts.