Hydrophilic pyrazine-based phosphane ligands: synthesis and application in asymmetric hydride transfer and H 2 -hydrogenation of acetophenone

Pyrazine-based hydrophilic phosphanes are useful ligands for the ruthenium- and rhodium-catalyzed hydrogenations of acetophenone under hydride transfer and dihydrogen conditions. The effect of alcohol additives on the catalytic, enantioselective aqueous hydrogenation of acetophenone is examined with the newly developed (R,R)-DAMPYPHOS as the ligand and Rh2(norbornadiene)2Cl2 as the catalyst precursor, giving rise to higher conversions (up to quantitative) and improved enantiomeric excesses (up to 95%) of the formed 1-phenylethanol.