负载(S)-脯氨酸手性固相催化剂制备和在不对称加氢反应中的应用

Preparation of Supported Chiral (S)-Proline/Palladium Catalyst and its Application in Enantioselective Hydrogenation of Acetophenone

用亲水性、高比表面积、硅烷化硅小球担载钯 ,以 (S) -脯氨酸为手性助剂、苯乙酮为反应底物 ,考察不对称加氢反应和不同有机碱助催化剂的影响 .实验表明 ,当使用三辛胺助催化剂时 ,(R) -苯乙醇的对映异构体选择性可达 1 7.5% .将 (S) -脯氨酸负载于亲水性、高比表面积、硅烷化硅小球担体表面 ,以 Pd(OAc) 2 为催化剂前体 ,制备负载型手性固相催化剂 ,初步考察了 (S) -脯氨酸与中心金属钯的摩尔比、疏水性不同的有机溶剂和有机碱助催化剂对不对称加氢反应的影响 ,以及该催化剂的循环使用情况 .结果表明 ,以 2 - (1 -环己烯基乙基胺为助催化剂 ,(R) -苯乙醇的立体选择性最高达到 1 2 .4%

Enantioselective hydrogenation of acetophenone catalyzed by palladium coated on silicanizated silica gel was carried out in the presence of ( S )\|proline. The effects of various basic additives as the promoters, such as triethylamine, 2\|methylpyridine etc., were also studied. Up to 17.5% ee was obtained for the hydrogenation of acetophenone. Depositing both ( S )\|proline and palladium on silicanized silica gel performs the heterogenization of this catalytic system. The supported chiral catalysts were also used in asymmetric hydrogenation of acetophenone. Optical yields as high as 12.4% were obtained using a catalyst containing ( S )\|proline/ palladium in molar ratio 3 and 2\|(1\|cyclohexenyl)ethylamine as the promoter. The supported chiral catalysts were separated and recovered by filtration after reaction. The effects of basic additives as the promoters and different solvents on enantioselectivity were also investigated.