2404-43-5Relevant academic research and scientific papers
An effective approach for the immobilization of chiral Mn(III) salen complexes through a supported ionic liquid phase
Lou, Lan-Lan,Yu, Kai,Ding, Fei,Zhou, Wei,Peng, Xiaojie,Liu, Shuangxi
, p. 6513 - 6516 (2006)
An effective method based on supported ionic liquid system was employed to immobilize chiral Mn(III) salen complexes. The prepared heterogeneous catalysts exhibited excellent activity and enantioselectivity in the asymmetric epoxidation of unfunctionalize
Synthesis of novel immobilized tridentate Schiff base dioxomolybdenum(VI) complexes as efficient and reusable catalysts for epoxidation of unfunctionalized olefins
Li, Yuedong,Fu, Xiangkai,Gong, Biwei,Zou, Xiaochuan,Tu, Xiaobo,Chen, Junxian
, p. 55 - 62 (2010)
A series of tridentate Schiff base dioxomolybdenum(VI) complexes have been immobilized onto modified synergistic organic-inorganic hybrid support chloromethyl-ZPS-PVPA [zirconium poly (styrene-phenylvinylphosphonate)-phosphate] to prepare a new type of heterogeneous catalyst. The as-synthesized catalysts exhibited good to excellent catalytic efficiency in epoxidation of unfunctionalized olefins, using tert-butyl hydroperoxide (TBHP) as oxidant. Surprisingly, up to 99% ee values were obtained when α-methylstyrene was chosen as substrate in this oxidant system with these heterogeneous catalysts. Furthermore, the immobilized catalyst showed a stable catalytic activity in manifold reuses.
Chiral porous poly(ionic liquid)s: Facile one-pot, one-step synthesis and efficient heterogeneous catalysts for asymmetric epoxidation of olefins
Tian, Yabing,Wang, Jixia,Zhang, Shiguo,Zhang, Yan
, (2022/01/26)
Ionic liquids are potential media/solvents for asymmetric synthesis when combined with chiral catalysts, while most reported catalysts are homogenous, making them difficult to separate from the reaction systems. Herein, chiral porous poly(ionic liquid)s (
Epoxide Electroreduction
Huang, Cheng,Lu, Qingquan,Ma, Wan,Qi, Xiaotian,Xu, Minghao,Zheng, Xuelian
supporting information, p. 1389 - 1395 (2022/01/19)
Selective hydrogenation of epoxides would be a direct and powerful approach for alcohol synthesis, but it has proven to be elusive. Here, electrochemically epoxide hydrogenation using electrons and protons as reductants is reported. A wide range of primary, secondary, and tertiary alcohols can be achieved through selective Markovnikov or anti-Markovnikov ring opening in the absence of transition metals. Mechanistic investigations revealed that the regioselectivity is controlled by the thermodynamic stabilities of the in situ generated benzyl radicals for aryl-substituted epoxides and the kinetic tendency for Markovnikov selective ring opening for alkyl-substituted epoxides.
Construction of an Asymmetric Porphyrinic Zirconium Metal-Organic Framework through Ionic Postchiral Modification
Berijani, Kayhaneh,Morsali, Ali
, p. 206 - 218 (2021/01/11)
Herein, one kind of neutral chiral zirconium metal-organic framework (Zr-MOF) was reported from the porphyrinic MOF (PMOF) family with a metallolinker (MnIII-porphyrin) as the achiral polytopic linker [free base tetrakis(4-carboxyphenyl)porphyrin] and chiral anions. Achiral Zr-MOF was chiralized through the exchange of primitive anions with new chiral organic anions (postsynthetic exchange). This chiral functional porphyrinic MOF (CPMOF) was characterized by several techniques such as powder X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, 1H NMR, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller measurements. In the resulting structure, there are two active metal sites as Lewis acid centers (Zr and Mn) and chiral species as Br?nsted acid sites along with their cooperation as nucleophiles. This CPMOF shows considerable bimodal porosity with high surface area and stability. Additionally, its ability was investigated in asymmetric catalyses of prochiral substrates. Interactions between framework chiral species and prochiral substrates have large impacts on the catalytic ability and chirality induction. This chiral catalyst proceeded asymmetric epoxidation and CO2 fixation reactions at lower pressure with high enantioselectivity due to Lewis acids and chiral auxiliary nucleophiles without significant loss of activity up to the sixth step of consecutive cycles of reusability. Observations revealed that chiralization of Zr-MOF could happen by a succinct strategy that can be a convenient method to design chiral MOFs.
Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
, p. 5077 - 5085 (2021/08/16)
Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
Immobilization of (tartrate-salen)Mn(III) polymer complexes into SBA-15 for catalytic asymmetric epoxidation of alkenes
Jia, Yihong,ALOthman, Zeid A.,Liang, Rui,Cha, Shuangshuang,Li, Xiaoyong,Ouyang, Weiyi,Zheng, Aqun,Osman, Sameh M.,Luque, Rafael,Sun, Yang
, (2020/08/19)
A series of (tartrate-salen)Mn(III) polymer complexes were prepared and immobilized into SBA-15, being subsequently employed as catalysts in the asymmetric epoxidation of alkenes. 1H NMR, FT-IR, UV–vis, elemental analysis, GPC and ICP-AES demonstrated the successful synthesis of polymer complexes, while powdered XRD, nitrogen physisorption and XPS studies proved the immobilization of polymer complexes into SBA-15. Both homogeneous and heterogeneous catalysis revealed that configurations of major epoxide products were still determined by salen chirality but e.e. values could be improved when tartrate and salen were configurationally identical. Combinations of (R,R)-salen with (R,R)-tartrate usually offered higher enantioselectivities. SBA-15 was satisfactory supporting material due to the high enantioselectivities and recycling yields obtained. The synthesized SBA-15-supported (tartrate-salen)Mn(III) catalysts showed continuous high enantioselectivities for epoxidation of α-methylstyrene, indicating great prospects for large-scale production.
Chirally-Modified Graphite Oxide as Chirality Inducing Support for Asymmetric Epoxidation of Olefins with Grafted Manganese Porphyrin
Ahadi, Elahe,Hosseini-Monfared, Hassan,Schlüsener, Carsten,Janiak, Christoph,Farokhi, Afsaneh
, p. 861 - 873 (2019/11/03)
Abstract: A chirality inducer was prepared by graphite oxide (GO) functionalization with enantiopure l-tartrate (GO*) and used as asymmetric support for a covalently-linked manganese porphyrine complex [Mn(TPyP)OAc]. The thereby obtained heterogeneous catalyst, GO*-[Mn(TPyP)OAc], showed excellent performance and ee-values of 92–99% for the asymmetric epoxidation of prochiral olefins with O2 as oxidant and isobutyraldehyde as co-reductant in acetonitrile; linear terminal olefins with 54–76% conversion and quantitative conversion of aromatic olefins. The GO*-[Mn(TPyP)OAc] catalyst is highly active, recyclable, and at the same time simple and inexpensive to prepare with a chiral inducer from the chiral pool. The structure of the catalyst was elucidated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET analysis,?FT-IR, Raman, and photoluminescence spectroscopic methods. Graphic Abstract: Graphite oxide functionalized with an enantiopure group was used as a chirality inducer and asymmetric support for a Mn-porphyrine complex. The thereby obtained heterogeneous catalyst is an excellent enantioselective catalyst for the epoxidation of prochiral olefins.[Figure not available: see fulltext.].
Asymmetric epoxidation of unfunctionalized olefins with C2-symmetrical diphenol-derived axially coordinated homogeneous chiral bi-Mn(III) salen complexes
Dong, Tianyi,Wu, Xiaoju,Cai, Jiali,Huang, Jing
, p. 57 - 61 (2019/01/19)
A novel type of C2-symmetrical diphenol-derived and axially coordinated homogeneous chiral bi-Mn(III) salen complexes are synthesized and their catalytic effects in asymmetric epoxidation of unfunctionalized olefins are investigated in details. The results show that excellent enantioselectivities and high activities are achieved (enantioselectivities up to >99% in 99.9%) in the absence of expensive NMO. Compared with Jacobsen's catalyst, the configuration of C2-symmetrical homogeneous chiral bi-Mn(III) salen complex contribute to the catalytic reactivity and stability. Furthermore, these new homogeneous catalysts could be easily recovered and reused for 5 cycles without significant loss of their properties.
Chiral salen Mn (III) immobilized on ZnPS-PVPA through alkoxyl-triazole for superior performance catalyst in asymmetric epoxidation of unfunctionalized olefins
Huang, Jing,Liu, Sirui,Ma, Yan,Cai, Jiali
supporting information, p. 27 - 33 (2019/02/28)
Chiral salen Mn (III) catalysts anchored onto ZnPS-PVPA via click chemistry are prepared and applied in asymmetric epoxidations of unfunctionalized olefins. Superior catalytic performances (conv%, up to >99; ee%, up to >99) are achieved in the epoxidations of α-methylstyrene, styrene, indene and 1-octene. According to 6-cyano-2,2-dimethylchromene and 6-nitro-2,2-dimethylchromene, configuration of epoxides are reversed. And then the catalysts are selective in not only oxidative systems, but also substrates. Moreover, superior reusability (yield, 82%; ee, 86%) after recycling for nine times could also be obtained, which provide the potential application in industry.
