62249-81-4Relevant academic research and scientific papers
An Amphiphilic (salen)Co Complex – Utilizing Hydrophobic Interactions to Enhance the Efficiency of a Cooperative Catalyst
Solís-Mu?ana, Pablo,Salam, Joanne,Ren, Chloe Z.-J.,Carr, Bronte,Whitten, Andrew E.,Warr, Gregory G.,Chen, Jack L.-Y.
supporting information, p. 3207 - 3213 (2021/06/01)
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.).
Enantioselective Radical-Polar Crossover Reactions of Indanonecarboxamides with Alkenes
Cao, Weidi,Feng, Xiaoming,Liu, Xiaohua,Wu, Wangbin,Xu, Xi,Yu, Han,Zhang, Xiying
supporting information, p. 4846 - 4850 (2020/02/11)
Highly efficient asymmetric intermolecular radical-polar crossover reactions were realized by combining a chiral N,N′-dioxide/NiII complex catalyst with Ag2O under mild reaction conditions. Various terminal alkenes and indanonecarboxamides/esters underwent radical addition/cyclization reactions to afford spiro-iminolactones and spirolactones with good to excellent yields (up to 99 %) and enantioselectivities (up to 97 % ee). Furthermore, a range of different radical-mediated oxidation/elimination or epoxide ring-opening products were obtained under mild reaction conditions. The Lewis acid catalysts exhibited excellent performance and precluded the strong background reaction.
Discovery of a Cyclic Choline Analog That Inhibits Anaerobic Choline Metabolism by Human Gut Bacteria
Bollenbach, Maud,Ortega, Manuel,Orman, Marina,Drennan, Catherine L.,Balskus, Emily P.
supporting information, p. 1980 - 1985 (2020/11/09)
The anaerobic conversion of choline to trimethylamine (TMA) by the human gut microbiota has been linked to multiple human diseases. The potential impact of this microbial metabolic activity on host health has inspired multiple efforts to identify small molecule inhibitors. Here, we use information about the structure and mechanism of the bacterial enzyme choline TMA-lyase (CutC) to develop a cyclic choline analog that inhibits the conversion of choline to TMA in bacterial whole cells and in a complex gut microbial community. In vitro biochemical assays and a crystal structure suggest that this analog is a competitive, mechanism-based inhibitor. This work demonstrates the utility of structure-based design to access inhibitors of radical enzymes from the human gut microbiota.
Functionalizable Stereocontrolled Cyclopolyethers by Ring-Closing Metathesis as Natural Polymer Mimics
Alkattan, Mohammed,Prunet, Jo?lle,Shaver, Michael P.
supporting information, p. 12835 - 12839 (2018/09/25)
Whereas complex stereoregular cyclic architectures are commonplace in biomacromolecules, they remain rare in synthetic polymer chemistry, thus limiting the potential to develop synthetic mimics or advanced materials for biomedical applications. Herein we
Precursor effect on the property and catalytic behavior of Fe-TS-1 in butadiene epoxidation
Wu, Mei,Zhao, Huahua,Yang, Jian,Zhao, Jun,Song, Huanling,Chou, Lingjun
, p. 2103 - 2109 (2017/10/06)
The effect of iron precursor on the property and catalytic behavior of iron modified titanium silicalite molecular sieve (Fe-TS-1) catalysts in butadiene selective epoxidation has been studied. Three Fe-TS-1 catalysts were prepared, using iron nitrate, iron chloride and iron sulfate as precursors, which played an important role in adjusting the textural properties and chemical states of TS-1. Of the prepared Fe-TS-1 catalysts, those modified by iron nitrate (FN-TS-1) exhibited a significant enhanced performance in butadiene selective epoxidation compared to those derived from iron sulfate (FS-TS-1) or iron chloride (FC-TS-1) precursors. To obtain a deep understanding of their structure-performance relationship, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Temperature programmed desorption of NH3 (NH3-TPD), Diffuse reflectance UV–Vis spectra (DR UV–Vis), Fourier transformed infrared spectra (FT-IR) and thermal gravimetric analysis (TGA) were conducted to characterize Fe-TS-1 catalysts. Experimental results indicated that textural structures and acid sites of modified catalysts as well as the type of Fe species influenced by the precursors were all responsible for the activity and product distribution.
3,4-epoxy-1-butene preparation method
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Paragraph 0032-0035, (2017/03/18)
The present invention relates to a 3,4-epoxy-1-butene preparation method. A purpose of the present invention is mainly to solve the problems of low raw material conversion rate, low product yield and serious waste in the prior art. The technical scheme co
A broadly applicable and practical oligomeric (salen)Co catalyst for enantioselective epoxide ring-opening reactions
White, David E.,Tadross, Pamela M.,Lu, Zhe,Jacobsen, Eric N.
supporting information, p. 4165 - 4180 (2014/06/09)
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.
Catalytic properties of heteropoly compounds in 1,3-butadiene oxidation with hydrogen peroxide
Kuznetsova,Kuznetsova,Maksimovskaya,Koshcheeva,Utkin
, p. 420 - 430 (2013/12/04)
The homogeneous oxidation of 1,3-butadiene (BD) in H2O 2-HPC-CH3CN (HPC = heteropoly compound) solutions has been investigated. The route of the reaction depends on the nature of the metal capable of coordinating with active oxygen in the HPC. The products of radical BD oxidation (acrolein, 3-butene-1,2-diol, 2-butene-1,4-diol, furan) form in the presence of H3+n PMo12 - n V n O40 (n = 1, 2) acids. 3,4-Epoxy-1-butene (EB) and acrolein + furan, which form in equal amounts in the presence of the (n-Bu4N)5PW 11O39Fe(OH) salt, result, respectively, from the electrophilic addition of hydrogen peroxide to BD and from radical BD oxidation on iron-oxygen complexes in the HPC composition. The reaction carried out in the presence of (n-Bu4N)3{PO4[WO(O 2)2]4}, (n-Bu4N)5Na 0.6H1.4PW11O39, or (EMIm) 5NaHPW11O39 yields EB with high selectivity on the reacted BD basis (up to 97%) and H2O2 (about 100%). The formation and conversion of the phosphotungstate peroxo complexes PW n O m α- (n = 2, 3, 4) that are active in BD epoxidation have been investigated by 31PNMR spectroscopy. The role of the tetrabutylammonium and ethylmethylimidazolium cations in the formation of these complexes has been demonstrated.
Preparation, characterization and catalytic performance study of La-TS-1 catalysts
Wu, Mei,Song, Huanling,Chou, Lingjun
, p. 23562 - 23570 (2013/11/19)
Lanthanum (La) was substituted into a titanium silicalite 1 (TS-1) framework via two different synthetic approaches, i.e., in situ hydrothermal synthesis and ultrasonic immersing methods. La inhibited Ti to enter into the TS-1 framework during in situ hydrothermal synthesis, and thus Ti erosion gave rise to poor catalytic activity for butadiene (BD) epoxidation. While catalysts prepared by an ultrasonic immersing method were testified as fine ones by mutually complementary characterization and catalytic tests. Extraframework-La and Si-OH caused by framework-La enhanced the acidity of TS-1. Adequate intensity of acidity aroused from 8 wt% La modified had activated H 2O2 for BD epoxidation rather than promoting the solvolysis reactions of the epoxide. Moreover, interactions between framework-La and the Ti active center via O weakened the [Ti-O] bond, which facilitated active intermediate formation. As a result, H2O2 conversion and utilization, along with vinyloxirane (VO) yield and TON were highly promoted with appropriate content of La modified.
The positive role of cadmium in TS-1 catalyst for butadiene epoxidation
Wu, Mei,Song, Huanling,Wang, Fang,Chou, Lingjun
, p. 207 - 212 (2013/10/08)
A series of Cd modified titanium silicalite 1 catalysts with different Cd content (xCd-TS-1, x = 1-15) were successfully prepared by ultrasound impregnation. Epoxidation of butadiene over these catalysts were investigated using hydrogen peroxide as oxidant, which indicated that Cd greatly improve the catalytic performance of TS-1 and the selectivity of epoxide. Various characterization methods including quantum chemical calculation were employed to explore the specific roles of Cd in promoting TS-1 catalytic activity. Theoretical calculation consistently suggested TiO bond were weakened owing to the introduction of Cd, which resulted in the structure of Cd-TS-1 becoming more relaxant. As a consequence, it is favorable to methanol solvent and H 2O2 interacting with the Ti active site to form five-member transition state during reaction. It was observed that catalysts modified with 1-5 wt% Cd presented both high catalytic activity and good reusability. The highest yield of 0.63 mol/L of vinyloxirane (VO) was obtained, while turnover number (TON, determined as the molar VO obtained per molar Ti atom) could reach to 1466.
