- Induced salt-responsive circularly polarized luminescence of hybrid assemblies based on achiral Eu-containing polyoxometalates
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The first circularly polarized luminescence of achiral Eu-containing polyoxometalates (POMs) was realized by electrostatic assembly with a diblock copolymer containing bulky chiral pendants, and was unexpectedly enhanced by NaCl. The induced chirality is attributed to static coupling causing chiral torsion of POMs and dynamic coupling between organic chiral chromophores and an Eu emission center.
- Shi, Nan,Tan, Junyan,Wan, Xinhua,Guan, Yan,Zhang, Jie
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- Synthesis of Novel (9S)-Acyloxy Derivatives of Quinidine and Dihydroquinidine as Insecticidal Agents
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Endeavor to discover biorational natural products-based insecticides, two series (30) of novel (9S)-acyloxy derivatives of quinidine and dihydroquinidine were prepared and assessed for their insecticidal activity against Mythimna separata in vivo by the leaf-dipping method at 1 mg/mL. Among all the compounds, especially four derivatives exhibited the best insecticidal activity with final mortality rates of 71.4 %, 75.0 %, 71.4 %, and 75.0 %, respectively. Relatively speaking, 9-hydroxy group is well tolerated, and the results showed that after modification of the hydroxy group with an acyloxy group, the insecticidal activity was significantly increased; the configuration at C8/9 position is important for insecticidal activity, and the (9S)-configuration is optimal; modification of the out-ring double bond is acceptable, and hydrogenation of the double bond enhances insecticidal activity. These preliminary results will pave the way for further modification of quinidine in the development of potential new insecticides.
- Che, Zhiping,Yang, Jinming,Sun, Di,Tian, Yuee,Liu, Shengming,Lin, Xiaomin,Jiang, Jia,Chen, Genqiang
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- Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation
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The enantioselective amination of C(sp3)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh2(esp)2, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C-H amination of substrates bearing pendant hydroxyl groups. Additionally, the quinoline of the chiral cation appears to engage in axial ligation to the rhodium complex, providing improved yields of product versus Rh2(esp)2 and highlighting the dual role that the cation is playing. These results underline the potential of using chiral cations to control enantioselectivity in challenging transition-metal-catalyzed transformations.
- Fanourakis, Alexander,Paterson, Kieran J.,Phipps, Robert J.,Williams, Benjamin D.
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supporting information
p. 10070 - 10076
(2021/07/21)
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- Hydroquinidine compound, preparation method and application thereof, and botanical insecticide
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The invention relates to a hydroquinidine compound, a preparation method and application thereof, and a botanical insecticide, and belongs to the technical field of botanical insecticides. The structural formula of the hydroquinidine compound provided by the invention is shown in a formula I, wherein R is selected from C1-C4 alkyl, phenyl, mono-substituted phenyl and disubstituted phenyl, and substituents of the mono-substituted phenyl and the disubstituted phenyl are separately and independently selected from C1-C4 alkyl, halogen or nitro. The hydroquinidine compound shown in the formula I has obvious insecticidal activity and has an obvious control effect on armyworm, and the control effect on armyworm is equal to or even exceeds a control effect of commercial botanical insecticide toosendanin, so that the hydroquinidine compound can be used for preparing the botanical insecticide.
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Paragraph 0057-0058; 0060-0072
(2020/01/12)
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- Catalytic Enantio- and Diastereoselective Mannich Addition of TosMIC to Ketimines
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Chiral amines bearing a stereocenter in the α position are ubiquitous compounds with many applications in the pharmaceutical and agrochemical sectors, as well as in catalysis. Catalytic asymmetric Mannich additions represent a valuable method to access such compounds in enantioenriched form. This work reports the first enantio- and diastereoselective addition of commercially available p-toluenesulfonylmethyl isocyanide (TosMIC) to ketimines, affording 2-imidazolines bearing two contiguous stereocenters, one of which is fully-substituted, with high yields and excellent stereocontrol. The reaction, catalyzed by silver oxide and a dihydroquinine-derived N,P-ligand, is broad in scope, operationally simple, and scalable. Derivatization of the products provides enantioenriched vicinal diamines, precursors to NHC ligands and sp3-rich heterocyclic scaffolds. Computations are used to understand catalysis and rationalize stereoselectivity.
- Franchino, Allegra,Chapman, Jack,Funes-Ardoiz, Ignacio,Paton, Robert S.,Dixon, Darren J.
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supporting information
p. 17660 - 17664
(2018/11/10)
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- Synthesis of Quinuclidines by Intramolecular Silver-Catalysed Amine Additions to Alkynes
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A new method has been developed for the synthesis of 2-alkylidenequinuclidines based on a silver triflate catalysed intramolecular hydroamination of 4-(prop-2-ynyl)piperidines. Monosubstituted piperidines reacted less efficiently than cis-disubstituted piperidines, and the reaction was selective for an alkyne moiety, even in the presence of a vinyl group at the 3-position. The hydroamination occurred readily with a terminal alkyne, as well as with an internal alkyne bearing an aliphatic or aromatic group at the terminal carbon atom. Using this silver-catalysed cyclization, a short procedure was developed for the relay synthesis of the cinchona alkaloids dihydroquinidine and dihydroquinine. We report the synthesis of (enantiomerically pure) 2-alkylidenequinuclidines by an intramolecular hydroamination reaction catalysed by silver triflate. After cyclization to the appropriate quinuclidines, the cinchona alkaloids dihydroquinidine and dihydroquinine were obtained in a two-step procedure.
- Breman, Arjen C.,Ruiz-Olalla, Andrea,Van Maarseveen, Jan H.,Ingemann, Steen,Hiemstra, Henk
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p. 7413 - 7425
(2016/02/20)
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- Transfer hydrogenations of alkenes with formate on Pd/C: Synthesis of dihydrocinchona alkaloids
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Protocols for preparative (1-80 gram scale) transfer hydrogenations of alkenes over a palladium on carbon catalyst using formic acid/ammonium formate as hydrogen donor are presented. Cinchona alkaloids have been converted to their dihydro derivatives in >94% yield. Georg Thieme Verlag Stuttgart - New York.
- Wu, Haotian,Hintermann, Lukas
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p. 888 - 892
(2013/05/09)
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- Organocatalytic asymmetric direct vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to nitroolefins
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The first organocatalytic enantioselective direct vinylogous Michael reaction of α,β-unsaturated γ-butyrolactam to nitroolefins is developed using cinchona alkaloids as the catalysts. Both product enantiomers are accessible with moderate to good enantioselectivity.
- Choudhury, Abhijnan Ray,Mukherjee, Santanu
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supporting information; experimental part
p. 7313 - 7320
(2012/10/07)
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- Total syntheses of racemic and natural glycinol
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Total syntheses of racemic and (-)-glycinol (1) are described. A Wittig reaction produced the isoflav-3-ene from which a Sharpless dihydroxylation introduced either the racemic or enantiomeric 6a-hydroxy group. A 5.5% overall yield of racemic material was obtained after 12 steps. A method was devised for a one-pot switch of protecting groups masking a sensitive resorcinolic para-functionality, and conditions were optimized to prompt spontaneous closure of the pterocarpanolic dihydrofuran upon subsequent exposure of its ortho-functionality. These improvements eliminated two steps and increased the overall yield to 9.8% during production of the natural enantiomer.
- Luniwal, Amarjit,Khupse, Rahul S.,Reese, Michael,Fang, Lei,Erhardt, Paul W.
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supporting information; experimental part
p. 2072 - 2075
(2010/04/29)
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- Simple enantiospecific synthesis of sulfides of Cinchona alkaloids
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The native and epi-Cinchona alkaloids were reacted with (ArS) 2/Bu3P in toluene at 65 °C to give the corresponding arylsulfanyl derivatives (15 examples, 31-75%) with complete inversion of configuration at 9-C stereogenic centers. Similar products were also obtained in the enantiospecific nucleophilic substitution of the 9-mesylates of alkaloids with sodium thiolates (4 examples, 73-84%) and no cinchona rearrangement was observed. The chiral thioethers obtained were preliminarily tested as N(sp 3), S-donating chiral ligands in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenylprop-2-enyl acetate and gave the product with up to 78% ee. Georg Thieme Verlag Stuttgart.
- Zielinska-Blajet, Mariola,Kucharska, Malgorzata,Skarzewski, Jacek
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p. 1176 - 1182
(2007/10/03)
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- Heterogeneous enantioselective hydrogenation of ethyl pyruvate catalyzed by cinchona-modified Pt catalysts: Effect of modifier structure
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The effect of the structure of chiral modifiers derived from natural cinchona alkaloids on the enantioselectivity and rate of the Pt/Al2O3-catalyzed hydrogenation of ethyl pyruvate was investigated. The influence of the following structural elements was studied: The cinchonidine versus the cinchonine backbone; effect of the nature and the size of substituents attached to C9; effect of partial hydrogenation of the quinoline ring; effects of changes of the substituent at the quinuclidine moiety. The strongest effects on ee and somewhat less on rate were observed for changes in the O-C9-C8-N part of the cinchona alkaloid and for partial or total hydrogenation of the quinoline rings. The nature of the substituents in the quinuclidine part had a comparably minor influence. The solvent was found to have a significant effect on enantioselectivity and rate. In acetic acid, the best results were obtained with O-methyl-10,11-diydrocinchonidine (ee's up to 93%), whereas dihydrocinchonidine was the most effective modifier in toluene. In agreement with a basic model proposed by Pfaltz, it was concluded that the minimal-requirements for an efficient modifier for the hydrogenation of α-keto esters is the presence of a basic nitrogen center close to one or more stereogenic centers and connected to an aromatic system. The results are in qualitative agreement with mechanistic models based on hydrogen-bonding interactions between an adsorbed modifier molecule and adsorbed ethyl pyruvate or its half-hydrogenated intermediate.
- Blaser,Jalett,Lottenbach,Studer
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p. 12675 - 12682
(2007/10/03)
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- IMPROVED SYNTHESIS OF EPIBRASSINOLIDE
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An improved synthesis of epibrassinolide is described.The product is the first of a group of brassinosteroids, which has found use a plant growth regulator.Among the proposed improvements for its production the most important position is the development of a stereoselective method for construction of the side chain by the oxidation of the Δ22-bond with osmium tetroxide in the presence of 10,11-dihydroquinidine p-chlorobenzoate.
- Khripach, V. A.,Zhabinskii, V. A.,Ol'khovik, V. K.,Ivanova, G. I.,Zhernosek, E. V.,Kotyatkina, A. I.
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p. 1735 - 1740
(2007/10/03)
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- Facilitation of turnover in the ADH by additives which catalyze the hydrolysis of the OS(VI) glycolate esters
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Osmium-catalyzed methods of addition to an olefin are discussed. In the method of asymmetric dihydroxylation of the present invention, an olefin, a chiral ligand, an organic solvent, water, an oxidant, an osmium-containing compound and an organic soluble anion are combined. The presence of the organic soluble anion allows the asymmetric dihydroxylation reaction to occur rapidly and the amount of olefin that is diydroxylated is high with concomitantly less chiral ligand and osmium-containing catalyst than previously achieved.
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- Ligands for ADH: cinchona alkaloids and moderately sized organic substituents linked through a planar aromatic spacer group
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Osmium-catalyzed methods of addition to an olefin are discussed. In the method of asymmetric dihydroxylation of the present invention, an olefin, a chiral ligand, an organic solvent, an aqueous solution, a base, a ferricyanide salt and an osmium-containing compound are combined. The chiral ligand is an alkaloid or alkaloid derivative linked to an organic substituent of at least 300 daltons molecular weight through a planar aromatic spacer group. The organic substituent can be another alkaloid or alkaloid derivative. With the described chiral ligands, asymmetric dihydroxylation of olefins with high yields and enantiomeric excesses are achieved.
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- Methods for catalytic asymmetric dihydroxylation of olefins
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Osmium-catalyzed methods of addition to an olefin are discussed. In the method of asymmetric dihydroxylation of the present invention, an olefin, a chiral ligand, an organic solvent, water, an oxidant and an osmium-containing compound are combined. In the method of asymmetric oxyamination of the present invention, an olefin, a chiral ligand, an organic solvent, water, a metallo-chloramine derivative, an osmium-containing compound and, optionally, a tetraalkyl ammonium compound are combined. In the method of asymmetric diamination of the present invention, an olefin, a chiral ligand, an organic solvent, a metallo-chloramine derivative, an amine and an osmium-containing compound are combined. In one embodiment, an olefin, a chiral ligand which is a polymeric dihydroquinidine derivative or a dihydroquinine derivative, acetone, water, a base, an oxidant and osmium tetroxide are combined to effect asymmetric dihydroxylation of the olefin.
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- Ligand-accelerated catalytic asymmetric dihydroxylation
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An osmium-catalyzed method of addition to an olefin. In the method of asymmetric dihydroxylation of the present invention, an olefin, a chiral ligand, an organic solvent, water, an amine oxide an osmium-containing compound and, optionally a tetraalkyl ammonium compound are combined. In the method of asymmetric oxyamination of the present invention, an olefin, a chiral ligand, an organic solvent, water, an amine derivative, an osmium-containing compound and, optionally, a tetraalkyl ammonium compound are combined. In the method of asymmetric diamination of the present invention, an olefin, a chiral ligand, an organic solvent, a metallo-chloramine derivative or an amine derivative and an osmium-containing compound are combined. In one embodiment, an olefin, a chiral ligand which is a dihydroquinidine derivative or a dihydroquinine derivative, acetone, water, N-methyl morpholine N-oxide and osmium tetroxide are combined to effect asymmetric dihydroxylation of the olefin.
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- Ligand-accelerated catalytic asymmetric dihydroxylation using dihydroquinidine and dihydroquinidine esters as ligands
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An osmium-catalyzed method of addition to an olefin. In the method of asymmetric dihydroxylation of the present invention, an olefin, a chiral ligand, an organic solvent, water, and aamine oxide and an osmium-containing compound are combined. In the method of asymmetric oxyamination of the present invention, an olefin, a chiral ligand, an organic solvent, water, an amine derivative and an osmium-containing compound are combined. In the method of asymmetric diamination of the present invention, an olefin, a chiral ligand, an organic solvent, a metallo-chloramine derivative or an amine derivative and an osmium-containing compound are combined. In one embodiment, an olefin, a chiral ligand which is a dihydroquinidine derivative or a dihydroquinine derivative, acetone, water, N-methyl morpholine N-oxide and osmium tetroxide are combined to effect asymmetric dihydroxylation of the olefin.
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