Asymmetric Hydrogenation of Acetophenone and Its derivatives Catalyzed by (1S,2S) -DPEN Modified Ir/γ-Al2O3

Under the basic conditions, an efficient catalyst without any stabilizer was prepared and applied in the asymmetric hydrogenation of acetophenone and its derivatives. The effects of different base, concentration of (1S,2S)-diphenylethylenediamine[(1S,2S)-DPEN] and base, reaction temperature and pressure of hydrogen on the asymmetric hydrogenation of acetophenone were investigated in detail. The results showed that this catalytic system had high activity and moderate enantioselectivity for the asymmetric hydrogenation of acetophenone and its derivatives. Under the optimum conditions, a good enantiomeric excess(e.e.) value of 80.3% was obtained for asymmetric hydrogenation of isobutyrophenone. Especially, the catalyst preparation is simple and no stabilizer was applied. The catalyst performance is steady and the catalyst can be reused several times through the facilitative separation of the catalyst from the reaction medium.