Short‐Mesochannel SBA‐15‐Supported Chiral 9‐Amino Epicinchonine for Asymmetric Transfer Hydrogenation of Aromatic Ketones

Abstract

AbstractA short‐mesochannel SBA‐15 material functionalized with propylthiol groups was prepared by co‐condensation and applied to the immobilization of chiral 9‐amino epicinchonine. After complexing with [Ir(cod)Cl]2 (cod=1,5‐cyclooctadiene), these mesoporous materials were evaluated as catalysts for the asymmetric transfer hydrogenation of aromatic ketones. Higher enantioselectivities and comparable, or even higher, catalytic activities were achieved compared with the free catalyst. Both the short mesochannel and co‐condensation approach for short‐mesochannel SBA‐15 materials functionalized with propylthiol groups, [SSBA‐SH(x)] materials were demonstrated to contribute to the excellent catalytic performance. In addition, the catalyst SSBA‐AEC(5)/Ir (AEC=9‐amino epicinchonine), with low 3‐mercaptopropyltrimethoxysilane (MPTMS) content, showed the best catalytic performance; a high enantiomeric excess of 84 % (homogeneous ee=60 %) along with a conversion of 97 % was achieved within 1 h for asymmetric transfer hydrogenation of acetophenone. Moreover, these immobilized catalysts showed high stability during the reaction and could be recovered for reuse.