The direct asymmetric aldol reaction between various aldehydes and acetone catalyzed by L-proline catalyst was successfully carried out in supercritical CO2 (scCO2) and 1,1,1,2-tetrafluoroethane (R-134a) fluids.The enantioselectivity of 84% ee to the targeted product was achieved under 20 MPa,40 °C,and 15 mol% of the catalyst in supercritical CO2 (scCO2) fluid.The effects of reaction parameters,such as temperature,pressure,catalyst loading and different substituted aldehydes on both enantioselectivity and aldol yield were discussed.The titled reaction was also performed in 1,1,1,2-tetrafluoroethane,and the obtained results were compared with those in scCO2.This new reaction procedure provides an environmental asymmetric aldol reaction system as compared with that in organic solvents.
LIU Ling1,LIU Zhao-Tie1,2*,LIU Zhong-Wen1,2 & XUE Dong1,2 1Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University),Ministry of Education,Xi’an 710062,China 2School of Chemistry & Materials Science,Shaanxi Normal University,Xi’an 710062,China
