122210-64-4Relevant academic research and scientific papers
A novel chiral manganese-tetraamide macrocycle complex covalently attached to magnetite as recyclable catalyst for aerobic asymmetric epoxidation of olefins
Hadian-Dehkordi, Leila,Hosseini-Monfared, Hassan,Aleshkevych, Pavlo
, p. 142 - 151 (2017)
A novel Mn complex containing N4-tetradentate tetraamide macrocyclic ligand (L) derived from chiral diethyl-2,3-benzylidene-L-tartrate and polyamidoamine dendrimer on Fe3O4@SiO2 surface was synthesized. The nanocomposite particles were investigated by SEM, XRD, VSM, EPR and FTIR. The nanocomposite showed high catalytic activity and selectivity for the epoxidation of linear terminal, cyclic and most of the aromatic olefins by O2 in the presence of isobutyraldehyde under mild conditions; epoxide selectivity 87–100%, enantiomeric excess 53–100%. The catalyst could be separated and recovered from the reaction system by applying an external magnetic field and reused for four cycles without the loss of activity after each cycle. Total TON of 16957 was obtained after four cycles.
Polyglycerol-supported Co- and Mn-salen complexes as efficient and recyclable homogeneous catalysts for the hydrolytic kinetic resolution of terminal epoxides and asymmetric olefin epoxidation
Beigi, Maryam,Roller, Sebastian,Haag, Rainer,Liese, Andreas
, p. 2135 - 2141 (2008)
In this report we demonstrate the suitability of hyperbranched polyglycerol as high-loading support for asymmetric catalysis. A polyglycerol-supported unsymmetrical salen ligand was prepared and purified by means of ultrafiltration. The polymeric ligand was metalated with cobalt acetate to afford the corresponding supported Co-salen complex which was further utilized in the hydrolytic kinetic resolution (HKR) of terminal epoxides. Kinetic studies for HKR of 1,2-epoxy-hexane using polyglycerol-supported Co-salen showed improved catalytic performance compared to the respective non-immobilized catalyst. This observation points to the presence of a positive dendrimeric effect assuming a cooperative bimetallic mechanism. Furthermore, a polymer-supported Mn-salen catalyst was prepared and successfully applied in the asymmetric epoxidation of olefins. The respective dendritic catalyst was recycled by precipitation up to three times in the epoxidation of 6-cyano-2,2-dimethylchromene (ee up to 95%). Experiments with repetitive batches revealed enhanced stability of the catalyst as a result of immobilization whereby the total turnover number increased from 23 in a single batch to around 80 for four repetitive batches. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Effect of the medium on the oxaziridinium-catalyzed enantioselective epoxidation
Lacour, Jerome,Monchaud, David,Marsol, Claire
, p. 8257 - 8260 (2002)
TRISPHAT salts of chiral iminium cations allow, in combination with 18-C-6, the use of biphasic CH2Cl2/water conditions, which can improve the enantioselectivity of the oxone-mediated epoxidation.
Polystyrene and polymethacrylate resin-supported Jacobsen's alkene epoxidation catalyst
Canali, Laetitia,Cowan, Elaine,Deleuze, Herve,Gibson, Colin L.,Sherrington, David C.
, p. 2055 - 2066 (2000)
Polystyrene and polymethacrylate-based resin supported Jacobsen's chiral Mn salen complexes have been prepared. The resins are of defined molecular structure and morphology, and the complexes have been attached primarily in a pendant fashion. The loadings of Mn(In) are in the range ～0.08-0.35 mmol g-1 to maximise the likelihood of site-isolation. The polymer-supported complexes have been used as enantioselective catalysts in the epoxidation of 1,2-dihydronaphthalene, indene, 1-phenylcyclohex-1-ene and 1-phenyl-3,4-dihydronaphthalene using m-chloroperbenzoic acid as the oxidant and 4-methylmorpholine N-oxide as the co-oxidant. Though the activities of the polymer catalysts are reduced relative to the soluble homogeneous analogue, the catalysts are sufficiently active to be useful. The corresponding reduction in enantioselectivity is more significant, and is both substrate and polymer resin dependent. However, in the case of 1-phenylcyclohex-1-ene and a macroporous polymethacrylate-based resin the enantioselectivity is equivalent to that of the soluble complex (91-92% ee). This is the first report of a polymersupported analogue of Jacobsen's catalyst being as selective as the homogeneous species. The catalysis data is discussed in detail in the context of the design of the polymer-supported system, and the existing data already available in the literature. Attempts have also been made to recycle the polymer catalysts with and without re-loading of Mn. In fact the level of leaching of Mn is very low, but the catalysts show a very rapid fall off in both activity and selectivity in the first and second cycles. Overall therefore it seems that the intrinsic stability of the chiral Mn(II) salen complex itself is too low to allow viable recycling, and the development of other more stable supported chiral metal salen complexes for use in other enantioselective reactions seems a better future option.
Polystyrene-supported triphenylarsines: Useful ligands in palladium-catalyzed aryl halide homocoupling reactions and a catalyst for alkene epoxidation using hydrogen peroxide
Song He, Helen,Zhang, Chuanxin,Ng, Chris Ka-Wo,Toy, Patrick H.
, p. 12053 - 12057 (2005)
The utility of both soluble (non-cross-linked) and insoluble (cross-linked) polystyrene-supported triphenylarsine reagents were examined. These reagents were prepared by standard radical polymerization methodology and used in palladium-catalyzed homocoupling reactions of aryl halides. The insoluble reagent was also used as a catalyst precursor in heterogeneous alkene epoxidation reactions in which aqueous hydrogen peroxide was the stoichiometric oxidant. For the aryl halide homocoupling reactions, both reagents worked well and afforded similar results. Unhindered aryl iodides afforded the best yields in the shortest reaction times compared to aryl bromides. The epoxidation reactions of unfunctionalized alkenes were not very efficient. This was probably due to the hydrophobicity of the polystyrene matrix, which did not swell in the reaction medium. Thus, since a microporous, gel-type polystyrene matrix was used, the majority of the arsine groups were inaccessible to the reaction components and therefore incapable of participating in catalysis.
Highly Enantioselective, Catalytic Epoxidation of Trisubstituted Olefins
Brandes, Bridget D.,Jacobsen, Eric N.
, p. 4378 - 4380 (1994)
Chiral (salen)Mn(III) complexes have been found to be highly selective catalysts for the asymmetric epoxidation of several cyclic and acyclic trisubstituted olefins.These results are interpreted with a transition-state model for epoxidation involving a sk
Effect of pore size on the performance of mesoporous material supported chiral Mn(III) salen complex for the epoxidation of unfunctionalized olefins
Yu, Kai,Gu, Zhicheng,Ji, Runan,Lou, Lan-Lan,Ding, Fei,Zhang, Cui,Liu, Shuangxi
, p. 312 - 320 (2007)
A series of mesoporous MCM-41 and MCM-48 materials with different pore sizes were synthesized and used as supports to immobilize chiral Mn(III) salen complex. The heterogeneous catalysts were characterized by XRD, FT-IR, DR UV-vis, and N2 sorpt
Functionalized iminium salt systems for catalytic asymmetric epoxidation
Page,Rassias,Barros,Ardakani,Buckley,Bethell,Smith,Slawin
, p. 6926 - 6931 (2001)
A range of dihydroisoquinolinium salts containing alcohol, ether, and acetal functionalities in the nitrogen substituent has been prepared and tested as asymmetric epoxidation catalysts, providing ee's of up to ca. 60%.
Aerobic Stereoselective Oxidation of Olefins on a Visible-Light-Irradiated Titanium Dioxide-Cobalt-Ascorbic Acid Nanohybrid
Jafarpour, Maasoumeh,Feizpour, Fahimeh,Rezaeifard, Abdolreza
, p. 235 - 238 (2017)
A visible-light-driven photocatalytically active nanocrystalline TiO2 was prepared by surface modification with a cobalt-ascorbic acid complex. The photocatalyst exhibited high activity and excellent chemo-, diastereo-, and stereoselectivities
Preparation of C 2-Symmetric Biaryl Bisiminium Salts and Their Use as Organocatalysts for Asymmetric Epoxidation
Bulman Page, Philip C.,Farah, Mohamed M.,Buckley, Benjamin R.,Chan, Yohan,Blacker, A. John
, p. 126 - 130 (2016)
Two C 2-symmetric bisiminium salt species containing biphenylazepinium units and derived from two chiral diamines were prepared and tested as organocatalysts for asymmetric epoxidation.
