- P-Tolyl glycerol ether: Is it possible to find more simple molecular organogelator with pronounced chirality driven properties?
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p-Tolyl glycerol ether not belonging to any of the known gelator families forms stable transparent gels in hydrocarbon media showing very good quantitative characteristics of gelling abilities, which are, in turn, strongly dependent on the chiral characteristics of the gelator. The crystal packing differences between the rac- and scal-substances could be the reason for such behaviour.
- Bredikhin, Alexander A.,Bredikhina, Zemfira A.,Akhatova, Flyura S.,Gubaidullin, Aidar T.
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Read Online
- Preparation method of high-quality (R)-3-chloro-1,2-propanediol
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The present invention relates to a high-quality (R)-3-chloro-1,2-propanediol preparation method, having the following steps: (R) - epichlorohydrin, (RR) Salen cobalt (III.) catalyst mixed reaction completely, diluted with water, filtered, separated (RR) Salen cobalt (III.) catalyst precipitated, followed by distillation of water under reduced pressure, and then distilled under reduced pressure to give (R)-3-chloro-1,2-propanediol. The chemical purity of (R)-3-chloro-1,2-propanediol prepared by this method >99.5%, chiral purity (EE) >99.8% has the advantages of simple synthesis, low cost and conducive to industrial applications.
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Paragraph 0018-0041
(2022/01/20)
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- An Amphiphilic (salen)Co Complex – Utilizing Hydrophobic Interactions to Enhance the Efficiency of a Cooperative Catalyst
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An amphiphilic (salen)Co(III) complex is presented that accelerates the hydrolytic kinetic resolution (HKR) of epoxides almost 10 times faster than catalysts from commercially available sources. This was achieved by introducing hydrophobic chains that increase the rate of reaction in one of two ways – by enhancing cooperativity under homogeneous conditions, and increasing the interfacial area under biphasic reaction conditions. While numerous strategies have been employed to increase the efficiency of cooperative catalysts, the utilization of hydrophobic interactions is scarce. With the recent upsurge in green chemistry methods that conduct reactions ‘on water’ and at the oil-water interface, the introduction of hydrophobic interactions has potential to become a general strategy for enhancing the catalytic efficiency of cooperative catalytic systems. (Figure presented.).
- Solís-Mu?ana, Pablo,Salam, Joanne,Ren, Chloe Z.-J.,Carr, Bronte,Whitten, Andrew E.,Warr, Gregory G.,Chen, Jack L.-Y.
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supporting information
p. 3207 - 3213
(2021/06/01)
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- TRICYCLIC HETEROARYL COMPOUNDS USEFUL AS IRAK4 INHIBITORS
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Disclosed are compounds of Formula (I) or a salt or prodrug thereof, wherein: X11 and X22 are independently C or N, provided that zero or one of X11 and X22 is N; Ring A represented by the structure is: or; and Q, R11, R22, R33, R44, R66, and p are define herein. Also disclosed are methods of using such compounds as modulators of IRAK4, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing inflammatory and autoimmune diseases, or in the treatment of cancer.
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Page/Page column 34-35
(2021/02/12)
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- Method for preparing aldehyde compounds through photocatalytic oxidation cracking β - hydroxyl compound C-C bond
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The invention provides a method for preparing aldehydes from C-C bonds of beta-hydroxy compounds by photocatalytic oxidative cracking. According to the method, the beta-hydroxy compounds are taken asa substrate, oxygen-containing gas is taken as an oxygen source, and C-C bond cracked products, namely, corresponding aldehydes can be generated under illumination in presence of a catalyst. The conditions are mild, the oxidation efficiency and the product yield are high, and the oxygen-containing gas is taken as the oxygen source under the illumination condition, so that the method is economical,environmentally friendly and green, meets the strategy of sustainable developed energy and has broad application prospect.
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Paragraph 0068-0069
(2020/07/29)
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- Enantioselective Resolution Copolymerization of Racemic Epoxides and Anhydrides: Efficient Approach for Stereoregular Polyesters and Chiral Epoxides
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Herein we report an efficient strategy for preparing isotactic polyesters and chiral epoxides via enantioselective resolution copolymerization of racemic terminal epoxides with anhydrides, mediated by enantiopure bimetallic complexes in conjunction with a nucleophilic cocatalyst. The chirality of both the axial linker and the diamine backbones of the ligand are responsible for the chiral induction of this kinetic resolution copolymerization process. The catalyst systems exhibit exceptional levels of enantioselectivity with a kinetic resolution coefficient exceeding 300 for various racemic epoxides, affording highly isotactic copolymers (selectivity factors of more than 300) with a completely alternating structure and low polydispersity index. Most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures in the range from 77 to 160 °C.
- Li, Jie,Ren, Bai-Hao,Wan, Zhao-Qian,Chen, Shi-Yu,Liu, Ye,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 8937 - 8942
(2019/06/11)
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- Aromatic donor-acceptor interaction promoted catalyst assemblies for hydrolytic kinetic resolution of epichlorohydrin
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Three generations of Co(iii)-salen complexes containing electron-deficient aromatic moieties (acceptors) have been synthesized. When electron-rich aromatic compounds (donors) were introduced, these complexes were designed to form catalyst assemblies through aromatic donor-acceptor interaction. For all three generations of complexes, the addition of a proper donor led to higher catalytic efficiency in the hydrolytic kinetic resolution (HKR) of epichlorohydrin. The reaction rates are in the following order: Generation 3 > Generation 2 > Generation 1. The aromatic donor-acceptor interaction was verified by NMR spectroscopy and UV-vis absorption spectroscopy studies. These results demonstrated that aromatic donor-acceptor interaction can be a valuable driving force in the assembly of supramolecular catalysts.
- Blechschmidt, Daniel R.,Woodhouse, Matthew D.,Inagaki, Sebastien,Whitfield, Melita,Ogunsanya, Ayokunnumi,Yoder, Aaron,Lilly, Daniel,Heim, Eric W.,Soucie, Luke N.,Liang, Jian,Liu, Yu
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supporting information
p. 172 - 180
(2019/01/04)
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- Aromatic Donor-Acceptor Interaction-Based Co(III)-salen Self-Assemblies and Their Applications in Asymmetric Ring Opening of Epoxides
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Aromatic donor-acceptor interaction as the driving force to assemble cooperative catalysts is described. Pyrene/naphthalenediimide functionalized Co(III)-salen complexes self-assembled into bimetallic catalysts through aromatic donor-acceptor interactions and showed high catalytic activity and selectivity in the asymmetric ring opening of various epoxides. Control experiments, nuclear magnetic resonance (NMR) spectroscopy titrations, mass spectrometry measurement, and X-ray crystal structure analysis confirmed that the catalysts assembled based on the aromatic donor-acceptor interaction, which can be a valuable noncovalent interaction in supramolecular catalyst development.
- Liang, Jian,Soucie, Luke N.,Blechschmidt, Daniel R.,Yoder, Aaron,Gustafson, Addie,Liu, Yu
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supporting information
p. 513 - 518
(2019/01/14)
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- Glycerin phosphatidyl choline preparation method
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The invention discloses a preparation method of glycerinum phosphatidylcholine. The preparation method comprises the following steps: (1) mixing a compound shown in formula (I) and anhydrous sodium carbonate to obtain a mixture M1; (2) placing the mixture M1 and (R)-(-)-3-chlorine-1,2-propanediol in anhydrous ethanol, and carrying out the refluxing to obtain a mixture M2; (3) filtering the mixture M2, carrying out the membrane separation, removing sodium chloride in the mixture M2, and obtaining filter liquid M3; (4) adding zinc chloride into the filter liquid M3, and dissolving the zinc chloride by adding water to obtain a mixture M4; (5) enabling the mixture M4 to flow by ion exchange resin, filtering the mixture M4, obtaining the filter liquid, and preparing the glycerinum phosphatidylcholine; (see the specifications), wherein R is Ca or Mg. By adopting the method, the glycerinum phosphatidylcholine is simple to prepare, and the yield is high, so that an effect of simple preparation method, high synthesis rate and low production cost can be realized.
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Paragraph 0056; 0057; 0058; 0059; 0060
(2018/04/20)
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- Glycerin phosphatidyl choline preparation method
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The invention discloses a preparation method for glycerophosphatidylcholine. The preparation method comprises the steps: mixing a compound shown in the formula (I) with anhydrous sodium carbonate to prepare a mixture M1; putting the mixture M1 and (R)-(-)-3-chloro-1,2-propylene glycol in anhydrous ethanol for reflux to obtain a mixture M2; after diluting the mixture M2 by 5-10 times, flowing the mixture M2 through first ion exchange resin to obtain a mixture M3; after diluting the mixture M3 by 2-4 times, flowing the mixture M3 through second ion exchange resin to obtain a mixture M4; washing the mixture M4 by 70-90wt% ethanol to obtain a mixture M5; washing the mixture M5 by distilled water to obtain a mixture M6; after flowing the mixture M6 through third ion exchange resin, filtering the mixture M6 to obtain a filtrate so as to obtain the glycerophosphatidylcholine. The formula (I) is as shown in the description, wherein R is Ca2 or Mg2. The effects of simple preparation method, high synthetic ratio and great reduction of production cost are achieved.
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Paragraph 0062-0066
(2017/12/28)
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- A Stereoselective Synthesis of the Carbon Backbone of Phoslactomycin B
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A convergent synthesis of the entire carbon framework of phoslactomycin B is disclosed. An initial route aimed to create the C-8 tetrasubstituted stereocentre through regioselective intermolecular coupling between an internal alkyne and an allyl silyl ether, adopting Trost's protocol, followed by [2,3] sigmatropic rearrangement. But this was not successful. In a second approach, a propargylic sulfide was rearranged to give an unsaturated ketone. This was then treated with lithio acetonitrile to create the C-8 stereocentre selectively. The C-4 and C-5 stereocentres were introduced by a non-Evans syn-aldol reaction using Crimmins's protocol. The C-9 and C-11 carbinol centres were created by asymmetric transfer hydrogenation. The (Z,Z)-diene moiety was introduced by partial reduction of a diyne following Hansen's modification of the Boland reduction reaction.
- Raghavan, Sadagopan,Patel, Javed Sardar
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supporting information
p. 2981 - 2997
(2017/06/06)
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- Preparation method of (R)-3-chloro-1, 2-propylene glycol
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The invention relates to a preparation method of (R)-3-chloro-1, 2-propylene glycol. The preparation method includes: mixing (R)-epoxy chloropropane, chiral organic acid and distilled water for reaction, cooling to room temperature, neutralizing, and depressurizing for distillation to obtain. The preparation method is simple and practical, the problem of heavy-metal pollution caused by using of a heavy metal catalyst can be effectively avoided, and the racemization problem of an inorganic acid catalyst is solved. Production yield is high and is more than 90%, product optical purity reaches higher than 99%e.e, and the preparation method has good industrialization prospect.
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Paragraph 0027; 0028
(2017/01/26)
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- Design and synthesis of binuclear Co-salen catalysts for the hydrolytic kinetic resolution of epoxides
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Three binuclear Co(III)-salen complexes have been synthesized based on a series of hydrophilic cyclic frameworks with different ring sizes. The catalytic performance of Co-salen complexes have further been evaluated in the hydrolytic kinetic resolution of racemic epoxides. And kinetic studies reveal that the binuclear Co-salen catalysts show a higher reactivity and better enantioselectivity in comparison to monometallic reference complex, indicating the two Co-salen units on the cyclic framework may work in a cooperative manner. Specifically, Co3, with the most flexible cyclic framework exhibits the best catalytic performance among the three catalysts, due to the efficient cooperative interactions between two cobalt centers.
- Wu, Fengshou,Wang, Kai,Li, Zaoying,Zhu, Xunjin
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p. 101 - 104
(2015/05/27)
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- Application of Mesoporous Silica Foam for Immobilization of Salen Complexes in Chiral Intermediates Synthesis
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A route to synthesize porous materials with a hierarchical micro/meso/macroscopic pore system was investigated. Meso/macroporous monolithic silica foams with a large pore size could be fabricated from a mixture of monodispersed PMMA beads and SBA-15, -16 sol solutions. The size, bulk shape and density of the mesoporous monolithic foam could be controlled by the container and the heat treatment temperature. Drying at temperatures higher than 300°C resulted in an expansion of the SBA silica sol and its solidification to form the mesoporous foams. In contrast, only a dense silica monolith was obtained after full evaporation of the solvent at room temperature without releasing the foam structure in the monolithic body. A large fraction of macroporosity in three dimensions was formed in the monolith body, and the remaining silica walls exhibited uniform mesoporosity. Hydrolytic and phenolic ring-opening of epoxides were performed successfully using chiral (salen)Co-BF3 complex-immobilized catalysts in the packed bed of a continuous flow system. Very high catalytic activity with desirable enantioselectivity was obtained in asymmetric catalysis.
- Jeon, Hoon-Gi,Choi, Seong Dae,Jeon, Sang Kwon,Park, Geun Woo,Yang, Jin Young,Kim, Geon-Joong
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p. 1396 - 1404
(2015/07/15)
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- Dinuclear salen cobalt complex incorporating Y(OTf)3: enhanced enantioselectivity in the hydrolytic kinetic resolution of epoxides
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The activation of inactive Jacobsen's chiral salen Co(ii) (salen = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine) compound is attained by dinuclear chiral salen Co(iii)-OTf complex formation with yttrium triflate. The yttrium metal not only displays a promoting effect on electron transfer, but also assists in forming two stereocentres of a Lewis acid complex with Co(iii)-OTf. We found that the binuclear Co-complex significantly enhanced reactivity and enantioselectivity in the hydrolytic kinetic resolution of terminal epoxides compared to its analogous monomer and kinetic data are also consistent with these results.
- Patel, Deepak,Kurrey, Ganesh Ram,Shinde, Sandip S.,Kumar, Pradeep,Kim, Geon-Joong,Thakur, Santosh Singh
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p. 82699 - 82703
(2015/10/19)
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- Synthesis of enantiomerically pure 3-aryloxy-2-hydroxypropanoic acids, intermediate products in the synthesis of cis-4-Aminochroman-3-ols
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Oxidation of accessible (R)-3-chloropropane-1,2-diol to (R)-3-chloro-2-hydroxypropanoic acid and subsequent reaction of the latter with ortho-substituted sodium phenoxide gave a number of enantiomerically pure 3-aryloxy-2-hydroxypropanoic acid which are intermediate products in the synthesis of nonracemic 4-aminochroman-3-ols.
- Bredikhina,Pashagin,Kurenkov,Bredikhin
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p. 535 - 539
(2014/06/10)
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- Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(iii)-salen complexes: A practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: Computational rationale for enantioselectivity
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A series of chiral polymeric Co(iii)-salen complexes based on a number of achiral and chiral linkers were synthesized and their catalytic performances were assessed in the asymmetric hydrolytic kinetic resolution of terminal epoxides. The effects of the linker were judiciously studied and it was found that in the case of the chiral BINOL-based polymeric salen complex 1, there was an enrichment in catalyst reactivity and enantioselectivity of the unreacted epoxide, particularly in the case of short as well as long chain aliphatic epoxides. Good isolated yields of the unreacted epoxide (up to 46% compared to 50% theoretical yield) along with high enantioselectivity (up to 99%) were obtained in most cases using catalyst 1. Further studies showed that catalyst 1 could retain its catalytic activity for six cycles under the present reaction conditions without any significant loss in activity or enantioselectivity. To show the practical applicability of the above synthesized catalyst we have synthesised some potent chiral β-blockers in moderate yield and high enantioselectivity using complex 1. The DFT (M06-L/6-31+G??//ONIOM(B3LYP/6-31G?:STO-3G)) calculations revealed that the chiral BINOL linker influences the enantioselectivity achieved with Co(iii)-salen complexes. Further, the transition state calculations show that the R-BINOL linker with the (S,S)-Co(iii)-salen complex is energetically preferred over the corresponding S-BINOL linker with the (S,S)-Co(iii)-salen complex for the HKR of 1,2-epoxyhexane. The role of non-covalent C-H?π interactions and steric effects has been discussed to control the HKR reaction of 1,2-epoxyhexane.
- Roy, Tamal,Barik, Sunirmal,Kumar, Manish,Kureshy, Rukhsana I.,Ganguly, Bishwajit,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 3899 - 3908
(2015/02/19)
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- A broadly applicable and practical oligomeric (salen)Co catalyst for enantioselective epoxide ring-opening reactions
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The (salen)Co catalyst (4a) can be prepared as a mixture of cyclic oligomers in a short, chromatography-free synthesis from inexpensive, commercially available precursors. This catalyst displays remarkable enhancements in reactivity and enantioselectivity relative to monomeric and other multimeric (salen)Co catalysts in a wide variety of enantioselective epoxide ring-opening reactions. The application of catalyst 4a is illustrated in the kinetic resolution of terminal epoxides by nucleophilic ring-opening with water, phenols, and primary alcohols; the desymmetrization of meso epoxides by addition of water and carbamates; and the desymmetrization of oxetanes by intramolecular ring opening with alcohols and phenols. The favorable solubility properties of complex 4a under the catalytic conditions facilitated mechanistic studies, allowing elucidation of the basis for the beneficial effect of oligomerization. Finally, a catalyst selection guide is provided to delineate the specific advantages of oligomeric catalyst 4a relative to (salen)Co monomer 1 for each reaction class.
- White, David E.,Tadross, Pamela M.,Lu, Zhe,Jacobsen, Eric N.
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p. 4165 - 4180
(2014/06/09)
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- Immobilized Aspergillus niger epoxide hydrolases: Cost-effective biocatalysts for the prepation of enantiopure styrene oxide, propylene oxide and epichlorohydrin
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This study aimed to prepare robust immobilized epoxide hydrolase (EH) preparations for asymmetric hydrolysis of racemic epoxides such as styrene oxide, propylene oxide and epichlorohydrin. For this purpose, Aspergillus niger EH was immobilized onto Lewatit VP OC 1600 support by adsorption, modified Florisil and Eupergit C supports by covalently. The suitability of the supports was examined for protein binding capacity and rate of racemic styrene oxide hydrolysis. The protein-activity recovery yields were 75-85%, 82-78% and 90-75%, respectively for EH immobilized onto Lewatit VP OC 1600, modified Florisil and Eupergit C supports. All A. niger EH preparations catalyzed preferentially hydrolysis of (R)-epoxides. Although enantiomeric excess values of all the tested epoxides were 99%, the highest enantiopure epoxide yields were obtained as 48% for (S)-styrene oxide by the immobilized EHs onto modified Florisil and Eupergit C. The highest diol yield was obtained as 78% for 3-chloro-1,2-propanediol, however, its enantiomeric excess value was 28.2%. Enantioselectivity of A. niger EH was improved with the preparation of mentioned immobilized forms. The highest enantioselectivity value was obtained as 95 toward styrene oxide by A. niger EH immobilized onto modified Florisil . The results of reusability studies show that the immobilized EH preparations offer feasible potentials for the preparation of enantiopure epoxides than that of free form.
- Yildirim, Deniz,Tuekel, S. Seyhan,Alptekin, Oezlem,Alagoez, Dilek
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- Novel highly active polymer supported chiral Co(III)-salen catalysts for hydrolytic kinetic resolution of epichlorohydrin
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A series of novel polymer supported chiral Co(III)-salen catalysts based on the hydroxyl functionalized gel-type resins, the HEMA resins, has been developed. The terpolymers used as supports for the immobilization of the salen catalysts were derived from the mixtures of 2-hydroxyethyl methacrylate (HEMA), styrene and different divinyl monomers (divinylbenzene, diethylene and triethylene glycol dimethacrylates, 1,4-butanediol and 1,6-hexanediol dimethacrylates). It was found that the novel catalysts show the high catalytic activity in the hydrolytic kinetic resolution (HKR) of rac-epichlorohydrin in the medium of THF, TBME, CH2Cl2 and CH3CN. tert-Butyl methyl ether appeared to be the best medium for performing the resolution. An effect of the nature of the polymer matrices on activity of the supported catalysts was also observed. The activity could be improved by optimization of HEMA concentration in the mixture of the monomers and by selection of the cross-linker. The most active catalyst was prepared based on the HEMA resin derived form 30 mol.% of HEMA and diethylene glycol dimethacrylate as a cross-linker. In the presence of this catalyst the HKR could be performed even at 0.01 mol.% concentration of Co(III) ions. The catalysts could be recycled 10th time at 0.5 mol.% concentration without any additional reactivation. It allowed conducting the HKR of epichlorohydrin within less than 60 min even in the 10th cycle. The catalyst with the highest loading of catalytic centers could be also used successfully for conducting the HKR of epichlorohydrin in solvent-free conditions. Its activity can be compared to the most active heterogeneous catalyst of the HKR described to date.
- Matkiewicz, Katarzyna,Bukowska, Agnieszka,Bukowski, Wiktor
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- Asymmetric hydrolytic kinetic resolution with recyclable macrocyclic CoIII-salen complexes: A practical strategy in the preparation of (R)-mexiletine and (S)-propranolol
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A chiral cobalt(III) complex (1 e) was synthesized by the interaction of cobalt(II) acetate and ferrocenium hexafluorophosphate with a chiral dinuclear macrocyclic salen ligand that was derived from 1R,2R-(-)-1,2-diaminocyclohexane with trigol bis-aldehyde. A variety of epoxides and glycidyl ethers were suitable substrates for the reaction with water in the presence of chiral macrocyclic salen complex 1 e at room temperature to afford chiral epoxides and diols by hydrolytic kinetic resolution (HKR). Excellent yields (47 % with respect to the epoxides, 53 % with respect to the diols) and high enantioselectivity (ee>99 % for the epoxides, up to 96 % for the diols) were achieved in 2.5-16 h. The CoIII macrocyclic salen complex (1 e) maintained its performance on a multigram scale and was expediently recycled a number of times. We further extended our study of chiral epoxides that were synthesized by using HKR to the synthesis of chiral drug molecules (R)-mexiletine and (S)-propranolol.
- Sadhukhan, Arghya,Khan, Noor-Ul H.,Roy, Tamal,Kureshy, Rukhsana I.,Abdi, Sayed H. R.,Bajaj, Hari C.
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supporting information; experimental part
p. 5256 - 5260
(2012/06/01)
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- Poly(styrene) resin-supported cobalt(III) salen cyclic oligomers as active heterogeneous HKR catalysts
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A cross-linked poly(styrene) support functionalized with cobalt(III) salen cyclic oligomers that can be used as a catalyst for the hydrolytic kinetic resolution (HKR) of terminal epoxides is reported. This catalyst is the most active heterogeneous catalyst to date for the HKR of terminal epoxides and can be recycled more than six times with excellent enantioselectivities for the HKR of epichlorohydrin. A 3-fold rate enhancement was observed when conducting the HKR reaction with 6 equivalents of water compared to 0.6 equivalents. We hypothesize that this rate enhancement is due to water sequestration of the diol product from the organic phase, thereby maintaining a high local concentration of epoxides and catalyst in the organic phase. Copyright
- Kahn, Michael G.C.,Stenlid, Joakim H.,Weck, Marcus
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supporting information
p. 3016 - 3024
(2013/01/15)
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- Asymmetric ring opening of terminal epoxides via kinetic resolution catalyzed by chiral (salen)Co mixture
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The highly enantioselective hydrolytic kinetic resolution (HKR) of racemic terminal epoxides by bimetallic chiral (salen)Co and (salen)Co(III)-OAc mixture provides a simple and effective method for the synthesis of enantiomerically enriched terminal epoxides (ee > 99%) and diols. At the equimolar amounts of bimetallic chiral (salen)Co and (salen)Co(II)-OAc, the catalytic activity increases more than two times in comparison with (salen)Co(III)-OAc used alone. The mixed catalytic system can be recycled and reused. No significant loss of catalytic activity was observed after three runs.
- Jiang, Chengjun
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experimental part
p. 691 - 696
(2011/11/30)
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- Stereoselective synthesis of (R)-glycidyl butyrate from racemic glycidyl butyrate or epichlorohydrin via hydrolytic kinetic resolution
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The differences of (R)-glycidyl butyrate synthesis via hydrolytic kinetic resolution of glycidyl butyrate directly or regioselective opening epichlorohydrin as key steps by using Jacobsen's hydrotic kinetic resolution are compared. In the view of separation problem, it is hard to get the pure (R)-glycidyl butyrate by kinetic resolution of glycidyl butyrate directly. Via kinetic resolution of epichlorohydrin, treatment with butyric acid in the presence of CrCl3 and then epoxidation with NaOH, the total yield of 38.5% and optical purity of 99% are obtained.
- Jiang, Chengjun,Yan, Jianbo
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scheme or table
p. 242 - 243
(2012/05/19)
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- Asymmetric synthesis of l-carnitine from (R)-3-chloro-1,2-propanediol
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A practical chemical synthesis of l-carnitine (1) has been accomplished from (R)-3-chloro-1,2-propanediol ((R)-4), which is a main by-product originated from (R,R)-Salen Co(III) catalyzed hydrolytic kinetic resolution (HKR) of (±)-epichlorohydrin. (R)-4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite ((R)-5). The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds.
- Li, Xu Qin,Yang, Yun Xu,Wang, Wei Li,Hu, Bin,Xue, Hui Min,Zhang, Tian Yi,Zhang, Xue Tao
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scheme or table
p. 765 - 767
(2012/01/03)
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- Self-assembly approach toward chiral bimetallic catalysts: Bis-urea-functionalized (Salen)cobalt complexes for the hydrolytic kinetic resolution of epoxides
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A series of novel bis-urea-functionalized (salen)Co complexes has been developed. The complexes were designed to form self-assembled structures in solution through intermolecular urea-urea hydrogen-bonding interactions. These bis-urea (salen)Co catalysts resulted in rate acceleration (up to 13atimes) in the hydrolytic kinetic resolution (HKR) of rac-epichlorohydrin in THF by facilitating cooperative activation, compared to the monomeric catalyst. In addition, one of the bis-urea (salen)CoIII catalyst efficiently resolves various terminal epoxides even under solvent-free conditions by requiring much shorter reaction time at low catalyst loading (0.03-0.05amol %). A series of kinetic/mechanistic studies demonstrated that the self-association of two (salen)Co units through urea-urea hydrogen bonds was responsible for the observed rate acceleration. The self-assembly study with the bis-urea (salen)Co by FTIR spectroscopy and with the corresponding (salen)Ni complex by 1HaNMR spectroscopy showed that intermolecular hydrogen-bonding interactions exist between the bis-urea scaffolds in THF. This result demonstrates that self-assembly approach by using non-covalent interactions can be an alternative and useful strategy toward the efficient HKR catalysis.
- Park, Jongwoo,Lang, Kai,Abboud, Khalil A.,Hong, Sukwon
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supporting information; experimental part
p. 2236 - 2245
(2011/03/22)
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- Practical and efficient utilisation of (R)-3-chloro-1,2-propanediol in synthesis of L-carnitine
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As a by-product originating from Salen Co(III) catalysed hydrolytic kinetic resolution (HKR) of (±)-epichlorohydrin in the manufacturing procedure of L-Carnitine, (R)-3-chloro-1,2-propanediol was utilised as a starting chiral material to prepare via key nitrile intermediates and by a final hydrolysis L-Carnitine. The new synthetic approach demonstrated an efficient utilisation of the by-product.
- Yang, Yunxu,Wang, Weili,Wumaier, Aikeremu,Sheng, Ruilong,Zhang, Xuetao,Zhang, Tianyi
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scheme or table
p. 371 - 372
(2011/10/09)
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- Shell cross-linked micelle-based nanoreactors for the substrate-selective hydrolytic kinetic resolution of epoxides
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Shell cross-linked micelles (SCMs) containing Co(III)-salen cores were prepared from amphiphilic poly(2-oxazoline) triblock copolymers. The catalytic activity of these nanoreactors for the hydrolytic kinetic resolution of various terminal epoxides was investigated. The SCM catalysts showed high catalytic efficiency and, more significantly, substrate selectivity based on the hydrophobic nature of the epoxide. Moreover, because of the nanoscale particle size and the high stability, the catalyst could be recovered easily by ultrafiltration and reused with high activity for eight cycles.
- Liu, Yu,Wang, Yu,Wang, Yufeng,Lu, Jie,Pinon, Victor,Weck, Marcus
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supporting information; experimental part
p. 14260 - 14263
(2011/11/05)
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- Investigating the anti-proliferative activity of styrylazanaphthalenes and azanaphthalenediones
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A group of styrylazanaphthalenes and azanaphthalenediones were synthesized and tested for their anti-proliferative activity. Most of the compounds were obtained with the use of microwave-assisted synthesis. The lipophilicity of the compounds was measured by RP-HPLC and their anti-proliferative activity was assayed against the human SK-N-MC neuroepithelioma and HCT116 human colon carcinoma cell lines. Active compounds were also tested in clonogenity and comet assays. Several quinazolinone and styrylquinazoline analogues were found to have markedly greater anti-proliferative activity than desferoxamine and cis-platin.
- Mrozek-Wilczkiewicz, Anna,Kalinowski, Danuta S.,Musiol, Robert,Finster, Jacek,Szurko, Agnieszka,Serafin, Katarzyna,Knas, Magdalena,Kamalapuram, Sishir K.,Kovacevic, Zaklina,Jampilek, Josef,Ratuszna, Alicja,Rzeszowska-Wolny, Joanna,Richardson, Des R.,Polanski, Jaroslaw
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scheme or table
p. 2664 - 2671
(2010/06/14)
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- Cooperative activation in the hydrolytic kinetic resolution of epoxides by a bis-cobalt(III)salen-calix[4]arene hybrid
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A chiral, bimetallic cobalt(III)salen-calix[4]arene hybrid structure was prepared and tested in the hydrolytic kinetic resolution (HKR) of racemic epoxides. Kinetic studies have revealed that the two catalytic units on the upper rim of the calixarene scaffold are able to activate the reactants in a cooperative and primarily intramolecular mode. High enantioselective behaviour was observed and besides, a higher stability was found for the bimetallic catalyst as compared to a monometallic reference complex.
- Wezenberg, Sander J.,Kleij, Arjan W.
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supporting information; experimental part
p. 85 - 91
(2010/06/21)
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- Highly active oligomeric Co(salen) catalysts for the asymmetric synthesis of α-aryloxy or α-alkoxy alcohols via kinetic resolution of terminal epoxides
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A mixture of Co(salen) macrocycles, prepared via the ring expansion metathesis oligomerization of salen-functionalized cyclooctene monomers, among the most active soluble catalysts for the hydrolytic kinetic resolution (HKR) of terminal epoxides, is exploited as the catalyst in the ring-opening of epoxides using aliphatic alcohols or phenols as nucleophiles, leading to the direct synthesis of optically active α-aryloxy alcohols or α-alkoxy alcohols. The catalyst is compared to other dimeric, oligomeric and monomeric Co(salen) complexes including a pimelate-linked macrocyclic Co(salen) catalyst and a dimeric Co(salen) catalyst referred to as a bisalen. The catalysts that contain multiple Co(salen) units within a single molecular framework allow for substantial decreases in catalyst loading compared with the monomeric catalyst. The cyclooctene-based Co(salen) macrocycle catalyst allows for good activity and enantioselectivity in the ring-opening of terminal epoxides with phenols as nucleophiles, giving enhanced turnover frequencies relative to many literature catalysts. The cyclooctene-based Co(salen) macrocycle catalyst and the bisalen catalysts are shown to be the most active in the asymmetric ring-opening of (±)1,2-epoxyhexane with methanol, out-performing the other catalysts tested. The Co(salen) macrocycle catalyst is recycled 3 times in this reaction with some loss in activity but no noteworthy change in selectivity.
- Zhu, Xunjin,Venkatasubbaiah, Krishnan,Weck, Marcus,Jones, Christopher W.
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body text
p. 1 - 6
(2010/11/04)
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- Factors influencing recyclability of Co(III)-salen catalysts in the hydrolytic kinetic resolution of epichlorohydrin
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The recyclability of Co(III)-salen catalysts, where salen is defined by (R,R)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine, for the hydrolytic kinetic resolution (HKR) of racemic epichlorohydrin is a strong function of the counterion of the Co(III)-salen catalyst. The nature of the counterion determines whether the HKR reaction follows primarily a bimetallic or monometallic reaction path, which significantly affects catalyst recyclability. For example, Co(III)-salen initially containing the nucleophilic Cl- counterion catalyzes the HKR of epichlorohydrin according to a bimetallic reaction path but loses activity upon recycle, as Cl- is replaced with OH- during the reaction. In contrast, a Co(III)-salen catalyst containing non-nucleophilic SbF6- counterion catalyzes the reaction according to a monometallic reaction path and is quite stable during multiple recycles, albeit at a low rate with less selectivity. A mixed catalyst system with Co(III)-salen initially containing Cl- to which Co(III)-salen with SbF6- is later added demonstrates high activity and high stability to recycling. Additional experiments with Co(III)-salen initially containing the acetate counterion reveal a progressive decline in activity with multiple recycles even after regeneration with acetic acid between runs, suggesting a destructive role of the regeneration process.
- Jain, Surbhi,Venkatasubbaiah, Krishnan,Jones, Christopher W.,Davis, Robert J.
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experimental part
p. 8 - 15
(2010/05/01)
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- Synthesis of carbon monolith with bimodal meso/macroscopic pore structure and its application in asymmetric catalysis
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Carbon monolith with bimodal meso/macroporous pore structures was synthesized by the nanocasting method, using corresponding monolith silica as templates. The pore system of this material was characterized by instrumental analysis. The adjacent macropores are interconnected through uniform-sized windows, and the walls of macrospheres consist of mesostructured pores. Chiral Co(III)-(BF3) salen immobilized on a meso/macroporous carbon monolith can be applied as an effective heterogeneous catalyst for an asymmetric reaction such as a hydrolytic kinetic reaction of terminal epoxides. The catalysts were prepared with different loading amounts of aluminium chloride to anchor the active salen complex, and the catalytic activity increased with increasing amount of aluminum chloride on the surfaces, showing up to 99 ee% of the product epichlorohydrin (ECH).
- Kim, Yong-Suk,Guo, Xiao-Feng,Kim, Geon-Joong
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experimental part
p. 91 - 99
(2010/11/17)
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- Highly active new chiral Co(iii) salen catalysts immobilized by electrostatic interaction with sulfonic acid linkages on ordered mesoporous SBA-16 silica
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New chiral cobalt(iii) salen complexes immobilized via HO 3S-linkers on ordered SBA-16 by electrostatic interactions showed very high activity in enantioselective ring-opening reactions of racemic epoxides.
- Kim, Yong-Suk,Guo, Xiao-Feng,Kim, Geon-Joong
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scheme or table
p. 4296 - 4298
(2011/03/19)
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- 1,3-Dibromo-5,5-dimethylhydantoin or N-bromosuccinimide as efficient reagents for chemoselective deprotection of 1,1-diacetates under solvent-free conditions
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A simple and efficient method is reported for rapid chemoselective transformation of 1,1-diacetates to the parent aldehydes using 1,3-dibromo-5,5-dimethylhydantoin or N-bromosuccinimide in the presence of wet SiO2 (50%, w/w) as solid support under solvent-free conditions at room temperature. This procedure has valuable advantages, for example short reaction times, simple work-up, high yields of products, absence of solvent, and use of commercially available and non-toxic reagents.
- Maleki, Behrooz,Azarifar, Davood,Ghorbani-Vaghei, Ramin,Veisi, Hojat,Hojati, Seyedeh Fatemeh,Gholizadeh, Mostafa,Salehabadi, Hafezeh,Moghadam, Mona Khodaverdian
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experimental part
p. 1485 - 1488
(2010/06/19)
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- Hydrolytic kinetic resolution of terminal epoxides catalyzed by novel bimetallic chiral Co (salen) complexes
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Novel bimetallic chiral Co (salen) complexes bearing transition-metal salts have been synthesized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity in hydrolytic kinetic resolution (HKR) of racemic terminal epoxides and consequently provided enantiomerically enriched epoxides (up to 99% ee). Copyright Taylor & Francis Group, LLC.
- Kawthekar, Rahul B.,Kim, Geon-Joong
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p. 1236 - 1248
(2008/09/18)
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- Iron-catalyzed asymmetric olefin cis-dihydroxylation with 97% enantiomeric excess
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Big cis-ster: The use of an (R,R)-bipyrrolidine backbone with two α-methylpyridine pendant arms affords a tetradentate N4 ligand that coordinates an iron center with cis-α topology (see picture; Fe purple, C gray, N blue, O red, S yellow, F green). This complex catalyzes the reaction between H2O2 and cis-2-heptene to afford a cis-diol product in very high enantioselectivity. (Figure Presented)
- Suzuki, Ken,Oldenburg, Paul D.,Que Jr., Lawrence
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p. 1887 - 1889
(2008/12/22)
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- Engineering polymer-enhanced bimetallic cooperative interactions in the hydrolytic kinetic resolution of epoxides
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Through systematic variations of the length of oligo(ethylene glycol)-based linkers and the catalyst density of poly(styrene)-supported cobalt-salen catalysts, we have elucidated an optimal catalyst flexibility and density of polymeric Co-salen catalysts for the hydrolytic kinetic resolution (HKR) of racemic terminal epoxides that follows a bimetallic cooperative pathway. The optimized polymeric catalyst brings the two cooperative Co-salen units to a favorable proximity efficiently and hence displays significantly improved catalytic performance in the HKR compared with its monomeric small molecule analogue. Complex Co(5b), representing the most active poly(styrene)-supported HKR catalyst known so far, can effect the resolution of a variety of epoxides to reach ≥ 98 % ee in 6-24 h with a low cobalt loading of 0.01-0.1 mol%.
- Zheng, Xiaolai,Jones, Christopher W.,Weck, Marcus
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supporting information; experimental part
p. 255 - 261
(2009/04/08)
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- Enhanced cooperativity in hydrolytic kinetic resolution of epoxides using poly(styrene) resin-supported dendronized co-(salen) catalysts
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Excellent enantioselectivities and isolated yields have been achieved for the hydrolytic kinetic resolution of epoxides using a resin-supported dendronized R,R-(salen)Co catalyst with catalyst loadings as low as 0.04 mol%, the lowest metal loadings of any heterogeneous resin-supported (salen)Co catalyst reported to date. In addition, the supported catalysts can be recycled and reused with comparable enantioselectivities. It is hypothesized that the high catalytic activity can be attributed to the flexible linker and the dendronized framework supporting the (salen)Co moieties on the resin thereby promoting cooperativity between two metal centers. This work opens up new opportunities for the design of highly active resin-supported catalysts that catalyze transformations through a bimetallic pathway.
- Goyal, Poorva,Zheng, Xiaolai,Weck, Marcus
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experimental part
p. 1816 - 1822
(2009/08/07)
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- Enhanced cooperativity through design: Pendant CoIII-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion)
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The CoIII-salen-catalyzed (salen = N,N'-bis(salicylidene) ethylenediamine dianion) hydrolytic kinetic resolution (HKR) of racemic epoxides has emerged as a highly attractive and efficient method of synthesizing chiral C3 building blocks for intermediates in larger, more complex molecules. HKR reaction rates have displayed a second order dependency on the concentration of active sites, and thus researchers have proposed a bimetallic transition state for the HKR mechanism. Here we report the utilization of pendant CoIII-salen catalysts on silica supported polymer brushes as a catalyst for the HKR of epichlorohydrin. The novel polymer brush architecture provided a unique framework for promoting site-site interactions as required in the proposed bimetallic transition state of the HKR mechanism. Furthermore, the polymer brushes mimic the environment of soluble polymer-based catalysts, whereas the silica support permitted facile recovery and reuse of the catalyst. The polymer brush catalyst displayed increased activities over the soluble Jacobsen Co-salen catalyst and was observed to retain its high enantioselectivities (> 99%) after each of five reactions despite decreasing activities. Analysis indicated decomposition of the salen ligand as an underlying cause of catalyst deactivation.
- Gill, Christopher S.,Venkatasubbaiah, Krishnan,Phan, Nam T. S.,Weck, Marcus,Jones, Christopher W.
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experimental part
p. 7306 - 7313
(2009/08/10)
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- 4(2)-Methoxyphenyl glycerol ethers in the synthesis of nonracemic di-O,O-acylglycerols
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Effective methods for the synthesis of nonracemic 4-and 2-methoxyphenyl glycerol ethers from nonracemic 3-chloropropanediols and by direct resolution of the racemate, respectively, were developed. Some existing discrepancies related to the to chiroptical properties of their derivatives were eliminated. Both ethers were used to synthesize nonracemic 3-O-aryloxy-1,2-di-O',O'-palmitoyl glycerols.
- Bredikhina,Novikova,Efremov,Sharafutdinova,Bredikhin
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experimental part
p. 2320 - 2323
(2010/02/15)
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- Continuous enantioselective kinetic resolution of terminal epoxides using immobilized chiral cobalt-salen complexes
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Jacobsen's cobalt-salen complex was covalently immobilized on polymer carriers that are part of different technical setups (polymer powder, composite Raschig rings, PASSflow microreactors) and employed for the enantioselective ring opening of terminal epoxides with water and phenols. The polymer-supported catalysts showed good activity and stereoselectivity and could be used repeatedly after a simple reactivation protocol in both batch as well as continuous-flow modes. Georg Thieme Verlag Stuttgart.
- Solodenko, Wladimir,Jas, Gerhard,Kunz, Ulrich,Kirschning, Andreas
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p. 583 - 589
(2007/12/25)
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- Asymmetric ring-opening of epoxides on chiral Co(Salen) catalyst synthesized in SBA-16 through the "ship in a bottle" strategy
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Chiral Co(Salen) complex was synthesized in the mesoporous cage of SBA-16 through the "ship in a bottle" method. The pore entrance size of SBA-16 was precisely tailored by varying the autoclaving time and silylation with phenyltrimethoxysilane to trap Co(Salen) complex in the cage of SBA-16. Chiral Co(Salen) trapped in SBA-16 shows enantioselectivity (up to 87-96% ee) as high as that of the homogeneous catalyst for the asymmetric ring opening of terminal epoxides and can be recycled at least 10 times with no apparent loss of activity. The activity for the catalyst trapped inside SBA-16 can be significantly increased when the surface is modified with organic groups. This work extends the "ship in a bottle" synthesis from microporous materials to mesoporous cage-like materials and develops an effective strategy to trap metal complex catalyst with large molecular size into the nanopores or cavities of mesoporous materials.
- Yang, Hengquan,Zhang, Lei,Su, Weiguang,Yang, Qihua,Li, Can
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p. 204 - 212
(2007/10/03)
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- Formal synthesis of herbarumin III
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An enantioselective synthesis of herbarumin III is described employing Jacobsen's hydrolytic kinetic resolution and Sharpless asymmetric dihydroxylation as the key steps.
- Gupta, Priti,Kumar, Pradeep
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p. 1688 - 1692
(2008/02/11)
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- Ring-expanding olefin metathesis: A route to highly active unsymmetrical macrocyclic oligomeric co-salen catalysts for the hydrolytic kinetic resolution of epoxides
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In the presence of the third generation Grubbs catalyst, the ring-expanding olefin metathesis of a monocyclooct-4-en-1-yl functionalized salen ligand and the corresponding Co(II)(salen) complex at low monomer concentrations results in the exclusive formation of macrocyclic oligomeric structures with the salen moieties being attached in an unsymmetrical, flexible, pendent manner. The TOF-MALDI mass spectrometry reveals that the resulting macrocyclic oligomers consist predominantly of dimeric to tetrameric species, with detectable traces of higher homologues up to a decamer. Upon activation under aerobic and acidic conditions, these Co(salen) macrocycles exhibit extremely high reactivities and selectivities in the hydrolytic kinetic resolution (HKR) of a variety of racemic terminal epoxides under neat conditions with very low catalyst loadings. The excellent catalytic properties can be explained in terms of the new catalyst's appealing structural features, namely, the flexible oligomer backbone, the unsymmetrical pendent immobilization motif of the catalytic sites, and the high local concentration of Co(salen) species resulting from the macrocyclic framework. This ring-expanding olefin metathesis is suggested to be a simple way to prepare tethered metal complexes that are endowed with key features - (i) a high local concentration of metal complexes and (ii) a flexible, single point of attachment to the support - that facilitate rapid and efficient catalysis when a bimetallic transition state is required.
- Zheng, Xiaolai,Jones, Christopher W.,Weck, Marcus
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p. 1105 - 1112
(2007/10/03)
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- Asymmetric reactions on chiral catalysts entrapped within a mesoporous cage
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The encapsulation of homogeneous chiral catalysts, e.g. Co(Salen) and Ru-TsDPEN, in the mesoporous cage of SBA-16 is demonstrated; the encapsulated catalysts show performance as good as that of the homogeneous catalysts, and can be recycled for more than 10 times without significant loss of catalytic performance. The Royal Society of Chemistry.
- Yang, Hengquan,Li, Jun,Yang, Jie,Liu, Zhimin,Yang, Qihua,Li, Can
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p. 1086 - 1088
(2008/01/03)
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- Studies of new indole alkaloid coupling methods for the synthesis of haplophytine
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The two novel bisindole alkaloid structures shown can be synthesized in a few steps from the canthiphytine derivative 9.
- Rege, Pankaj D.,Tian, Yuan,Corey
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p. 3117 - 3120
(2007/10/03)
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- Hydrolytic kinetic resolution of epoxides catalyzed by chromium(III)-endo, endo-2,5-diaminonorbornane-salen [Cr(III)-DIANANE-salen] complexes. Improved activity, low catalyst loading
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The hydrolytic kinetic resolution (HKR) of terminal epoxides, using chiral chromium(III)-salen catalysts based on DIANANE (endo,endo-2,5-diaminonorbornane) , was studied. A broad substrate scope was found for the chromium(III)-DIANANE catalysts, and very low loadings (down to 0.05 mol%) were needed to achieve high enantiomeric purities of both the remaining epoxides and the product diols (up to >99% ee). Besides monosubstituted epoxides, 2-methyl-2-n-pentyloxirane, which is an example for 2,2-disubstituted epoxides, could be ring-opened in an asymmetric fashion with water in the presence of an electronically tuned chromium-(III)-DIANANE complex.
- Berkessel, Albrecht,Ertuerk, Erkan
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p. 2619 - 2625
(2007/10/03)
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- Synthesis of optically pure terminal epoxide and 1,2-diol via hydrolytic kinetic resolution catalyzed by new heterometallic salen complexes
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The inactive chiral (salen)Co complex is easily activated by InCl 3 and TlCl3 Lewis acids by forming heterometallic salen complexes. These complexes show very high catalytic activity for the synthesis of enantiomerically enriched terminal epoxides (>99% ee) and 1,2-diols simultaneously via hydrolytic kinetic resolution. Strong synergistic effects of different Lewis acids, Co-In and Co-Tl, were exhibited in the catalytic process. The system described is very simple and efficient. Copyright Taylor & Francis Group, LLC.
- Thakur, Santosh Singh,Chen, Shu-Wei,Li, Wenji,Shin, Chang-Kyo,Koo, Yoon-Mo,Kim, Geon-Joong
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p. 2371 - 2383
(2007/10/03)
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- A new dinuclear chiral salen complexes for asymmetric ring opening and closing reactions: Synthesis of valuable chiral intermediates
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A new dinuclear chiral Co(salen) complexes bearing group 13 metals have been synthesized and characterized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity for the asymmetric ring opening of epoxides with H2O, chloride ions and carboxylic acids and consequently provide enantiomerically enriched terminal epoxides (>99% ee). It also catalyzes the asymmetric cyclization of ring opened product, to prepare optically pure terminal epoxides in one step. The homogeneous dinuclear chiral Co(salen) have been covalently immobilized on MCM-41. The potential benefits of heterogenization include facilitation of catalyst separation and recyclability requiring very simple techniques. The system described is very efficient.
- Thakur, Santosh Singh,Chen, Shu-Wei,Li, Wenji,Shin, Chang-Kyo,Kim, Seong-Jin,Koo, Yoon-Mo,Kim, Geon-Joong
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p. 1862 - 1872
(2007/10/03)
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