As a consequence of the increasing demand for atom economy and environmental friendly methods, the water soluble ligands and their metal complexes are of great interest in catalytic synthesis because of simpler pr... As a consequence of the increasing demand for atom economy and environmental friendly methods, the water soluble ligands and their metal complexes are of great interest in catalytic synthesis because of simpler product sepa ration and the possibility of recycling. [1] Unique reactivity and selectivity are often observed in aqueous reactions. [2]Recently, we have developed a new water-soluble chiral vicinal diamine and synthesized its mono-N-tosylated derivative for the first time. The application of its mono-N-tosylated derivative in catalytic asymmetric transfer hydrogenation of prochiral ketones was examined in aqueous media. High activity (up to ＞ 99 % conv. ) and good enatioselectivity ( up to 98% ee ) were achieved for most of prochiral aromatic ketones in organic solvent free system. [3]……展开更多
Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ～3] We achieved catalytic enantioselective Michael addition reactions ... Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ～3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.……展开更多
Enantioselective Michael addition is one of the most powerfulbond-forming reaction in organic synthesis. [1] A mong the Michael acceptors, nitro alkenes are very attractive, because the nitro group is the most ele... Enantioselective Michael addition is one of the most powerfulbond-forming reaction in organic synthesis. [1] A mong the Michael acceptors, nitro alkenes are very attractive, because the nitro group is the most electron-withdrawing group known and it can serve as masked functionality to be further transformed after the addition has taken place. [2] Recently, asymmetric Michael reactions catalyzed by organic catalyst have draw much attention.[3]……展开更多
Development of new methods for the introduction of a nitrogen atom to a carbonyl group is still the most important synthetic target. Cu-catalyzed addition of organozinc reagents to α,β-unsaturated carbonyl compo... Development of new methods for the introduction of a nitrogen atom to a carbonyl group is still the most important synthetic target. Cu-catalyzed addition of organozinc reagents to α,β-unsaturated carbonyl compounds has been the subject of intensive investigation.[1] Moreover, trapping of the intermediate Zn-enolates has been achieved using nitrosobenzene. To demonstrate the feasibility of developing enantioselective variants of these tandem C-C bond formations,α,β-unsaturated substrates a～d was subjected to standard reaction conditions using Feringa's (L1*, L2*) and our own phosphoramidite ligands (L3*, L4*). In this reaction, medium to high levels of enantioselectivities were observed.……展开更多
Very recently, we[1] found that L-proline amides and dipeptides acted as efficient catalysts for the asymmetric direct aldol reaction. We report here that L-proline-based peptides 1～5 can catalyze the aldol react... Very recently, we[1] found that L-proline amides and dipeptides acted as efficient catalysts for the asymmetric direct aldol reaction. We report here that L-proline-based peptides 1～5 can catalyze the aldol reactions of hydroxyacetone with aldehydes 6 in aqueous media, to give 1,4-diols (7), the disfavored products with either aldolase or L-proline. Both peptides 3 and 4 give good results.……展开更多
Since its introduction in 1997, tert-butanesulfinamide (1) has proven to an extremely versatile chiral ammonia equivalent for the asymmetric synthesis of amines[1]. However, practical methods for the preparation o... Since its introduction in 1997, tert-butanesulfinamide (1) has proven to an extremely versatile chiral ammonia equivalent for the asymmetric synthesis of amines[1]. However, practical methods for the preparation of enantiopure 1 are very few.[2]……展开更多
As our continuous efforts to search for easily accessible ligands for dialkylzinc addition to imines,[1] in this paper,we would like to present a family of chiral imino alcohols 3 derived from 1,2-diphenyl-2-amino... As our continuous efforts to search for easily accessible ligands for dialkylzinc addition to imines,[1] in this paper,we would like to present a family of chiral imino alcohols 3 derived from 1,2-diphenyl-2-aminoethanol which will be evaluated for the titled reaction. We believed that this kind of chiral ligands could be good chiral ligands for the diethylzinc addition to imines based on two points: (1) The excellent asymmetrically inductive properties of 1,2-diphenyl-2-aminoethanol and its derivatives have been proven in many reactions. (2) The conformation of the nitrogen in the chiral imines 3 is restricted by imine function which is similar to chiral oxazolines reported in our recent work.……展开更多
文摘 As a consequence of the increasing demand for atom economy and environmental friendly methods, the water soluble ligands and their metal complexes are of great interest in catalytic synthesis because of simpler product sepa ration and the possibility of recycling. [1] Unique reactivity and selectivity are often observed in aqueous reactions. [2]Recently, we have developed a new water-soluble chiral vicinal diamine and synthesized its mono-N-tosylated derivative for the first time. The application of its mono-N-tosylated derivative in catalytic asymmetric transfer hydrogenation of prochiral ketones was examined in aqueous media. High activity (up to ＞ 99 % conv. ) and good enatioselectivity ( up to 98% ee ) were achieved for most of prochiral aromatic ketones in organic solvent free system. [3]……
文摘 Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ～3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.……
文摘 Enantioselective Michael addition is one of the most powerfulbond-forming reaction in organic synthesis. [1] A mong the Michael acceptors, nitro alkenes are very attractive, because the nitro group is the most electron-withdrawing group known and it can serve as masked functionality to be further transformed after the addition has taken place. [2] Recently, asymmetric Michael reactions catalyzed by organic catalyst have draw much attention.[3]……
文摘 Development of new methods for the introduction of a nitrogen atom to a carbonyl group is still the most important synthetic target. Cu-catalyzed addition of organozinc reagents to α,β-unsaturated carbonyl compounds has been the subject of intensive investigation.[1] Moreover, trapping of the intermediate Zn-enolates has been achieved using nitrosobenzene. To demonstrate the feasibility of developing enantioselective variants of these tandem C-C bond formations,α,β-unsaturated substrates a～d was subjected to standard reaction conditions using Feringa's (L1*, L2*) and our own phosphoramidite ligands (L3*, L4*). In this reaction, medium to high levels of enantioselectivities were observed.……
文摘 Very recently, we[1] found that L-proline amides and dipeptides acted as efficient catalysts for the asymmetric direct aldol reaction. We report here that L-proline-based peptides 1～5 can catalyze the aldol reactions of hydroxyacetone with aldehydes 6 in aqueous media, to give 1,4-diols (7), the disfavored products with either aldolase or L-proline. Both peptides 3 and 4 give good results.……
文摘 Since its introduction in 1997, tert-butanesulfinamide (1) has proven to an extremely versatile chiral ammonia equivalent for the asymmetric synthesis of amines[1]. However, practical methods for the preparation of enantiopure 1 are very few.[2]……
文摘 As our continuous efforts to search for easily accessible ligands for dialkylzinc addition to imines,[1] in this paper,we would like to present a family of chiral imino alcohols 3 derived from 1,2-diphenyl-2-aminoethanol which will be evaluated for the titled reaction. We believed that this kind of chiral ligands could be good chiral ligands for the diethylzinc addition to imines based on two points: (1) The excellent asymmetrically inductive properties of 1,2-diphenyl-2-aminoethanol and its derivatives have been proven in many reactions. (2) The conformation of the nitrogen in the chiral imines 3 is restricted by imine function which is similar to chiral oxazolines reported in our recent work.……
