Cinchona alkaloids are utilized as chiral ligands to promote the enantioselective addition of dialkylzinc to N-diphenylphos-phinylimines affording enantiomerically enriched N-diphenyl-phosphinylamines in up to 91% ee.
Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversion...Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids.展开更多
The first direct asymmetric Mannich reaction of malononitrile to N-Boc-protected imines has been developed with cinchona alkaloid as catalyst. The procedure could tolerate a relatively wide range of substrates, and re...The first direct asymmetric Mannich reaction of malononitrile to N-Boc-protected imines has been developed with cinchona alkaloid as catalyst. The procedure could tolerate a relatively wide range of substrates, and results in excellent yields and good enantioselectivities even in the presence of only 1 mol% of catalyst loading. The present work provides an easy access to β-amino malononitrile derivatives.展开更多
We report herein a new class of polystyrene-supported cinchona alkaloid amide catalysts for enantioselective allylation of various aldehydes using allyltrichlorosilane under both batch and continuous flow conditions.T...We report herein a new class of polystyrene-supported cinchona alkaloid amide catalysts for enantioselective allylation of various aldehydes using allyltrichlorosilane under both batch and continuous flow conditions.The supported catalyst was synthesized using an environmentally benign coupling agent with a surfactant in aqueous media.Under batch conditions,consistently high yields and enantioselectivity were obtained for the allylation of aliphatic aldehydes with recycling and reuse of the catalyst for more than 10 runs.Subsequently,this catalytic system was successfully implemented into a packed bed flow reactor with similar efficiency and enantiose-lectivity.While flow is a viable option,the batch methodology has better potential for application at a larger-scale setting upon the comparison of space-time yield and catalyst loadings.With the sustainable synthesis and great recyclability of our polymeric catalyst,this methodology holds great potential for the large-scale delivery of valuable enantiopure homoallylic alcohols.展开更多
Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diaster...Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diastereoselectivities, computational chemists have contributed dramatic efforts in this important area. This review covers the recent computational studies on the cinchona alkaloid-catalyzed asymmetric Michael additions, including both C-C and C-S bond formations, to present a general viewpoint of these fruitful advances. Based on the types of bond formation and the cinchona alkaloid catalysts, key information regarding the activation model and the origins of enantioselectivities is discussed.展开更多
Optically active terminal 1,2-diols were prepared with high enantiopurity via the TMS-quinidine-catalyzed en- antioselective cyclization of acyl chlorides and oxaziridine, followed by reductive ring-opening of the cyc...Optically active terminal 1,2-diols were prepared with high enantiopurity via the TMS-quinidine-catalyzed en- antioselective cyclization of acyl chlorides and oxaziridine, followed by reductive ring-opening of the cycloadducts.展开更多
An efficient and enantioselective aerobic oxidation of 4-substituted pyrazolones has been developed by phase transfer catalysis.Using visible light as the driving force and O_(2)(in air)as the oxidant,broad scopes(38 ...An efficient and enantioselective aerobic oxidation of 4-substituted pyrazolones has been developed by phase transfer catalysis.Using visible light as the driving force and O_(2)(in air)as the oxidant,broad scopes(38 examples)of pyrazolones bearing an oxygen-attached carbon stereocenter at C-4 position were obtained in high yields(up to 98%)and excellent enantioselectivities(up to 93%ee)under mid conditions.The ready availability of catalyst,ease of operation,and low-cost and eco-friendly nature highlighted the practical utility of this visible lightpromoted enantioselective aerobic oxidation.展开更多
基金Project supported by the National Natural Science Foundation of China(No.20102005).
文摘Cinchona alkaloids are utilized as chiral ligands to promote the enantioselective addition of dialkylzinc to N-diphenylphos-phinylimines affording enantiomerically enriched N-diphenyl-phosphinylamines in up to 91% ee.
基金Research support from the National Science Foundation ofChina(No.21071116)Chongqing Scientific Foundation,China(No.2010BB4126)
文摘Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids.
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China (No. 21102071) and the Fundamental Research Funds for the Central Universities (Nos. 1107020522 and 1082020502). The Jiangsu 333 program (for Pan) and Changzhou Jin-Feng-Huang program (for Han) are also acknowledged.
文摘The first direct asymmetric Mannich reaction of malononitrile to N-Boc-protected imines has been developed with cinchona alkaloid as catalyst. The procedure could tolerate a relatively wide range of substrates, and results in excellent yields and good enantioselectivities even in the presence of only 1 mol% of catalyst loading. The present work provides an easy access to β-amino malononitrile derivatives.
基金supported by the Ministry of Education of Singapore(No.A-8000055-00-00)the National University of Singapore(No.A-0008372-00-00)+2 种基金Agency for Science,Technology and Research(A^(*)STAR)under its AME IRG Grant(No.A20E5c0096)the Institute of Sustainability for Chemicals,Energy and Environment(ISCE2)A^(*)STAR.N.X.Q.acknowledges the Agency for Science,Technology and Research(A^(*)STAR)for PhD scholarship.
文摘We report herein a new class of polystyrene-supported cinchona alkaloid amide catalysts for enantioselective allylation of various aldehydes using allyltrichlorosilane under both batch and continuous flow conditions.The supported catalyst was synthesized using an environmentally benign coupling agent with a surfactant in aqueous media.Under batch conditions,consistently high yields and enantioselectivity were obtained for the allylation of aliphatic aldehydes with recycling and reuse of the catalyst for more than 10 runs.Subsequently,this catalytic system was successfully implemented into a packed bed flow reactor with similar efficiency and enantiose-lectivity.While flow is a viable option,the batch methodology has better potential for application at a larger-scale setting upon the comparison of space-time yield and catalyst loadings.With the sustainable synthesis and great recyclability of our polymeric catalyst,this methodology holds great potential for the large-scale delivery of valuable enantiopure homoallylic alcohols.
基金Financial support from the National Natural Science Foundation of China (NSFC, No. 21702182)the Chinese "Thousand Youth Talents Plan+1 种基金Fundamental Research Funds for the Central Universities"Zhejiang University
文摘Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diastereoselectivities, computational chemists have contributed dramatic efforts in this important area. This review covers the recent computational studies on the cinchona alkaloid-catalyzed asymmetric Michael additions, including both C-C and C-S bond formations, to present a general viewpoint of these fruitful advances. Based on the types of bond formation and the cinchona alkaloid catalysts, key information regarding the activation model and the origins of enantioselectivities is discussed.
基金Acknowledgement This work was supported by the National Natural Science Foundation of China (No. 21072195) and the Major State Basic Research Development Program (No. 2011CB808600).
文摘Optically active terminal 1,2-diols were prepared with high enantiopurity via the TMS-quinidine-catalyzed en- antioselective cyclization of acyl chlorides and oxaziridine, followed by reductive ring-opening of the cycloadducts.
基金We would like to thank the University Key Research Projects of Henan Province(No.19A350009)Natural Science Foundation of Henan Province(No.202300410321)for their support.
文摘An efficient and enantioselective aerobic oxidation of 4-substituted pyrazolones has been developed by phase transfer catalysis.Using visible light as the driving force and O_(2)(in air)as the oxidant,broad scopes(38 examples)of pyrazolones bearing an oxygen-attached carbon stereocenter at C-4 position were obtained in high yields(up to 98%)and excellent enantioselectivities(up to 93%ee)under mid conditions.The ready availability of catalyst,ease of operation,and low-cost and eco-friendly nature highlighted the practical utility of this visible lightpromoted enantioselective aerobic oxidation.