Highly selective asymmetry transfer hydrogenation of prochiral acetophenone catalyzed by palladium–chitosan on silica

The chitosan–palladium catalyst supported on silica was prepared and used to catalyze an asymmetry transfer hydrogenation of prochiral acetophenone to alcohol with formate salts as a hydrogen donor at atmosphere. The results indicate that palladium coordinates with amino group in chitosan to form palladium–chitosan complex and its performance for an asymmetry transfer hydrogenation of acetophenone is affected greatly by the reaction temperature, hydrogen donor and solvent. For the hydrogenation of acetophenone over the palladium–chitosan–silica catalyst, the suitable solvent is ethanol and hydrogen donor is ammonium formate or sodium formate. Using ammonium formate as H-donor at atmosphere and 80 °C, an enantiomeric excess of R-1-phenylethanol reaches 68.9%.