An approach based on combinations of various water compatible Lewis acids and lipophilic group containing amphiphilic prolinamide co-catalysts has been evaluated for the direct asymmetric Aldol reaction. From the broa...An approach based on combinations of various water compatible Lewis acids and lipophilic group containing amphiphilic prolinamide co-catalysts has been evaluated for the direct asymmetric Aldol reaction. From the broad screening of chloride salts from alkali metal to transition metal, LiC1, ZnCI2 and SnCI2 lead to the highest stereoselectivities. The optimized catalytic conditions （10 mol% prolinamide with 10 mol% MC12 or 20 mol% LiC1 at room temperature on water） gave anti-products with improved enantioselectivities （up to 99% ee） compared to the moderately stereoselective procedure based on prolinamide activation only.展开更多
Chiral organoeatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under -20℃. A series of ...Chiral organoeatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under -20℃. A series of aldol products was obtained from moderate to good yields（up to 98%） with excellent diastereoselectivities（up to 〉99：1） and enantioselectivities（up to 〉99%）. The aldol products m the system were separated by a-cyclodextrin via host-guest interaction and determined by chiral HPLC. The catalyst could be reused up to five times. The 4-substitution position played an important role in diastereoselectivitv and enantioselectivitv.展开更多
An efficient direct asymmetric aldol reaction with zinc triflate and prolinamides as combined catalysts is reported.A series of chiral prolinamides have been designed and used in the direct aldol reaction resulting in...An efficient direct asymmetric aldol reaction with zinc triflate and prolinamides as combined catalysts is reported.A series of chiral prolinamides have been designed and used in the direct aldol reaction resulting in the desired products with excellent yields(up to 94% yield) and high enantioselectivities(up to 96% ee).Water was found to play a significant role in the formation of the aldol products,which suggests a new strategy in the design of new organic catalysts.展开更多
Prolinamido-glycoside catalyzed asymmetric aldol reaction in aqueous media is reported. The reactions are rapid and highly stereoselective when water is used as solvent. The stereoselectivities were under influence of...Prolinamido-glycoside catalyzed asymmetric aldol reaction in aqueous media is reported. The reactions are rapid and highly stereoselective when water is used as solvent. The stereoselectivities were under influence of configurations of a prolyl residue of the catalyst and α-chiral aldehydes. Water soluble prolinamido-glycoside catalysts are easily separable from reaction mixture and can be recycled and re-used several times.展开更多
An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones.The...An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones.The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap, readily available and recyclable catalyst make this process promising to be developed for large-scale preparation of β-hydroxyl ketones.展开更多
文摘An approach based on combinations of various water compatible Lewis acids and lipophilic group containing amphiphilic prolinamide co-catalysts has been evaluated for the direct asymmetric Aldol reaction. From the broad screening of chloride salts from alkali metal to transition metal, LiC1, ZnCI2 and SnCI2 lead to the highest stereoselectivities. The optimized catalytic conditions （10 mol% prolinamide with 10 mol% MC12 or 20 mol% LiC1 at room temperature on water） gave anti-products with improved enantioselectivities （up to 99% ee） compared to the moderately stereoselective procedure based on prolinamide activation only.
基金Supported by the National Natural Science Foundation of China（No.21174052） and the Natural Science Foundation of Jilin Province of China（Nos.20160101311JC, 20170101105JC）.
文摘Chiral organoeatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under -20℃. A series of aldol products was obtained from moderate to good yields（up to 98%） with excellent diastereoselectivities（up to 〉99：1） and enantioselectivities（up to 〉99%）. The aldol products m the system were separated by a-cyclodextrin via host-guest interaction and determined by chiral HPLC. The catalyst could be reused up to five times. The 4-substitution position played an important role in diastereoselectivitv and enantioselectivitv.
基金the National Natural Science Foundation of China (20772056)Jiangsu 333 Program (for Pan) for the generous financial support+1 种基金The research funds for Pan from the Qing-Lan Program of Jiangsu Provincethe Kua-Shi-Ji Program of the Education Ministry of China
文摘An efficient direct asymmetric aldol reaction with zinc triflate and prolinamides as combined catalysts is reported.A series of chiral prolinamides have been designed and used in the direct aldol reaction resulting in the desired products with excellent yields(up to 94% yield) and high enantioselectivities(up to 96% ee).Water was found to play a significant role in the formation of the aldol products,which suggests a new strategy in the design of new organic catalysts.
文摘Prolinamido-glycoside catalyzed asymmetric aldol reaction in aqueous media is reported. The reactions are rapid and highly stereoselective when water is used as solvent. The stereoselectivities were under influence of configurations of a prolyl residue of the catalyst and α-chiral aldehydes. Water soluble prolinamido-glycoside catalysts are easily separable from reaction mixture and can be recycled and re-used several times.
基金Project supported by the National Natural Science Foundation of China （Nos. 20342007, 20462003, 20452001 and 20421202）.
文摘An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones.The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap, readily available and recyclable catalyst make this process promising to be developed for large-scale preparation of β-hydroxyl ketones.
