- Porphyrins and Azaporphines as Catalysts in Alkene Epoxidations with Peracetic Acid.
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The reactivities of five MnIII(Cl) - phorphinoids were compared in the catalytic alkene epoxidations in CH3CN solution with peracetic acid as primary oxidant.Porphyrins 1 and 2 bearing Cl and NO2 substituents showed the best efficiency while te
- Banfi, Stafano,Montanari, Fernando,Quici, Silvio,Barkanova, Svetlana. V.,Kaliya, Oleg L.,et al.
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- Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants: Evidence for Different Active Species and Epoxidation Mechanisms
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Iron complexes with chiral bipyrrolidine-derived aminopyridine (PDP) ligands are among the most efficient Fe-based bioinspired catalysts for regio- and stereoselective oxidation of C-H and C=C moieties with hydrogen peroxide. Besides hydrogen peroxide, other oxidants (peroxycarboxylic acids and organic hydroperoxides) can be effectively used. In this work, we have examined the mechanistic landscape of the Fe(PDP) catalyst family with various oxidants: H2O2, organic hydroperoxides, and peracids. The combined EPR spectroscopic, enantioselectivity, Hammett, Z-stilbene epoxidation stereoselectivity, and 18O-labeling data witness that the same oxoiron complexes [(L)FeV=O(OC(O)R)]2+ are the actual epoxidizing species in both the catalyst systems (L)Fe/H2O2/carboxylic acid and (L)Fe/AlkylOOH/carboxylic acid. On the contrary, in the systems (L)Fe/R2C(O)OOH (R2 = CH3 or 3-Cl-C6H4), in the presence or in the absence of carboxylic acid, the epoxidation is predominantly conducted by the acylperoxo-iron(III) intermediates [(L)FeIII(OOC(O)R2)]2+, in a concerted fashion.
- Zima, Alexandra M.,Lyakin, Oleg Y.,Ottenbacher, Roman V.,Bryliakov, Konstantin P.,Talsi, Evgenii P.
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- Mn(III)-Iodosylarene Porphyrins as an Active Oxidant in Oxidation Reactions: Synthesis, Characterization, and Reactivity Studies
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Mn(III)-iodosylarene porphyrin adducts, [Mn(III)(ArIO)(Porp)]+, were synthesized by reacting electron-deficient Mn(III) porphyrin complexes with iodosylarene (ArIO) at -60 °C and characterized using various spectroscopic methods. The [Mn(III)(ArIO)(Porp)]+ species were then investigated in the epoxidation of olefins under stoichiometric conditions. In the epoxidation of olefins by the Mn(III)-iodosylarene porphyrin species, epoxide was formed as the sole product with high chemoselectivities and stereoselectivities. For example, cyclohexene oxide was formed exclusively with trace amounts of allylic oxidation products; cis- and trans-stilbenes were oxidized to the corresponding cis- and trans-stilbene oxides, respectively. In the catalytic epoxidation of cyclohexene by an electron-deficient Mn(III) porphyrin complex and sPhIO at low temperature (e.g., -60 °C), the Mn(III)-iodosylarene porphyrin species was evidenced as the active oxidant that effects the olefin epoxidation to give epoxide as the product. However, at high temperature (e.g., 0 °C) or in the case of using an electron-rich manganese(III) porphyrin catalyst, allylic oxidation products, along with cyclohexene oxide, were yielded, indicating that the active oxidant(s) was not the Mn(III)-iodosylarene adduct but probably high-valent Mn-oxo species in the catalytic reactions. We also report the conversion of the Mn(III)-iodosylarene porphyrins to high-valent Mn-oxo porphyrins under various conditions, such as at high temperature, with electron-rich porphyrin ligand, and in the presence of base (OH-). The present study reports the first example of spectroscopically well-characterized Mn(III)-iodosylarene porphyrin species being an active oxidant in the stoichiometric and catalytic oxidation reactions. Other aspects, such as one oxidant versus multiple oxidants debate, also were discussed.
- Guo, Mian,Lee, Yong-Min,Seo, Mi Sook,Kwon, Yong-Ju,Li, Xiao-Xi,Ohta, Takehiro,Kim, Won-Suk,Sarangi, Ritimukta,Fukuzumi, Shunichi,Nam, Wonwoo
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- Grafted metallocalixarenes as single-site surface organometallic catalysts
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Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-TiIV precursors were anchored at surface dens
- Notestein, Justin M.,Iglesia, Enrique,Katz, Alexander
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- The role of solvent friction in an orbital symmetry controlled reaction: Ring closure of a carbonyl ylide to cis-2,3-diphenyloxirane
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The dynamics of the orbital symmetry controlled ring closure of the trans-ylide, formed upon the 266 nm photolysis of trans-2,3-diphenyloxirane, to produce cis-2,3-diphenyloxirane is examined in a variety of n-alkane solvents as a function of temperature. An unsuccessful attempt was made to model the kinetics within the theoretical framework developed by Kramers for a one-dimensional reaction coordinate. A model developed by Grote and Hynes that employs a frequency-dependent friction was found to give a significantly better fit to the experimental data. The possibility that a multidimensional reaction coordinate is necessary to describe the reaction dynamics is discussed.
- Lipson, Matthew,Peters, Kevin S.
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- EPOXIDATION REACTIONS CATALYZED BY IRON PORPHYRINS. OXYGEN TRANSFER FROM IODOSYLBENZENE.
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The epoxidation of olefins by iodosylbenzene is catalyzed by synthetic iron porphyrins. With (chloro-5, 10, 15, 20 -tetraphenylporphyrinato) iron(III) (FeTPPCl), cyclohexadiene oxide was produced in 93% yield and with (chloro-5, 10, 15, 20-tetra-o-tolyporphyrinato) iron (III) (FeTTPCl), cycloctene oxide was produced in 84% yield. Cis olefins were found to be more reactive than trans olefins. Thus, whereas cis-stilbene was epoxidized by FeTPPCl/iodosylbenzene in 77% yield, trans-stilbene was unreactive under these conditions. The degree of cis/trans selectivity was a sensitive function of substitution of the porphyrin periphery. With (chloro-5, 10, 15, 20-tetramesitylporphyrinato)iron(III), the relative reactivity of cis-and trans-cyclododecene was 8. 92:1. Similarly, the less reactive cis double bond of trans, trans, cis-cyclododecatriene could be selectively epoxidized by this catalyst. Trans 1,2-disubstituted double bonds showed similar reactivities. These results suggest an approach of the double bond from the side of iron-bound oxygen and parallel to the prophyrin plane. A mechanism involving formation of an oxygen transfer from a reactive iron-oxo intermediate is proposed for this reaction.
- Groves,Nemo
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- A novel and efficient catalytic epoxidation of olefins with adducts derived from methyltrioxorhenium and chiral aliphatic amines
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Nitrogen-based adducts derived from methyltrioxorhenium(VII) and chiral aliphatic amines have been synthesized and applied to the efficient catalytic epoxidation of olefins with urea hydrogen peroxide complex as the primary oxidant. These complexes retain their catalytic activity when microencapsulated in polystyrene. A moderate steroinduction was obtained in the epoxidation of prochiral olefins with complexes between methyltrioxorhenium and chiral trans-1,2-cyclohexyldiamine. The values of steroinduction were found to increase after the microencapsulation process.
- Vezzosi, Stefano,Guimerais Ferre, Anna,Crucianelli, Marcello,Crestini, Claudia,Saladino, Raffaele
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- Picosecond Photochemistry of 2,3-Diphenyloxyranes: Reaction from a Vibrationally Unrelaxed Electronic Excited State
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Picosecond photochemistry of trans-1,2-diphenyloxirane (Ia) and cis-1,2-diphenyloxirane (Ib) is studied in cyclohexane and acetonitrile after 266-nm excitation by a 25-ps laser pulse.Carbonyl ylides, IIa and IIb, are formed by disrotatory opening of the s
- Manring, Lewis E.,Peters, Kevin S.
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- Asymmetric Epoxidation of Unfunctionalized Olefins Using Novel Chiral Dihydroisoquinolinium Salts as Organocatalysts
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Abstract: Two new non-racemic chiral dihydroisoquinolinium salts with N-substituents bulkier than a methyl group have been synthesized from (1S,2R)-norephedrine. These salts were used to catalyze asymmetric epoxidation of a series of prochiral olefins. One of the two new catalysts provided higher enantioselectivities (up to 66% ee) than the reference salt containing an N-methyl substituent.
- Ali, K. Ben
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p. 638 - 646
(2021/06/02)
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- Nonheme manganese(III) complexes for various olefin epoxidation: Synthesis, characterization and catalytic activity
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Three mononuclear imine-based non-heme manganese(III) complexes with tetradentate ligands which have two deprotonated phenolate moieties, ([(X2saloph)Mn(OAc)(H2O)], 1a for X = Cl, 1b for X = H, and 1c for X = CH3, saloph = N,N-o-phenylenebis(salicylidenaminato)), were synthesized and characterized by 1H NMR, 13C NMR, ESI-Mass and elemental analysis. MnIII complexes catalysed efficiently various olefin epoxidation reactions with meta-chloroperbenzoic acid (MCPBA) under the mild condition. MnIII complexes 1a and 1c with the electron-withdrawing group -Cl and electron-donating group –CH3 showed little substituent effect on the epoxidation reactions. Product analysis, Hammett study and competition experiments with cis- and trans-2-octene suggested that MnIV = O, MnV = O, and MnIII-OOC(O)R species might be key oxidants in the epoxidation reaction under this catalytic system. In addition, the use of PPAA as a mechanistic probe demonstrated that Mn-acylperoxo intermediate (MnIII-OOC(O)R) 2 generated from the reaction of peracid with manganese complexes underwent both the heterolysis and the homolysis to produce MnV = O (3) or MnIV = O species (4). Moreover, the MnIII-OOC(O)R 2 species could react directly with the easy-to-oxidize substrate to give epoxide, whereas the species 2 might not be competent to the difficult-to-oxidize substrate for the epoxidation reaction.
- Lee, Sojeong,Park, Soyoung,Lee, Myoung Mi,Lee, Jiyoung,Kim, Cheal
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- Effect of the Ligand Backbone on the Reactivity and Mechanistic Paradigm of Non-Heme Iron(IV)-Oxo during Olefin Epoxidation
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The oxygen atom transfer (OAT) reactivity of the non-heme [FeIV(2PyN2Q)(O)]2+ (2) containing the sterically bulky quinoline-pyridine pentadentate ligand (2PyN2Q) has been thoroughly studied with different olefins. The ferryl-oxo complex 2 shows excellent OAT reactivity during epoxidations. The steric encumbrance and electronic effect of the ligand influence the mechanistic shuttle between OAT pathway I and isomerization pathway II (during the reaction stereo pure olefins), resulting in a mixture of cis-trans epoxide products. In contrast, the sterically less hindered and electronically different [FeIV(N4Py)(O)]2+ (1) provides only cis-stilbene epoxide. A Hammett study suggests the role of dominant inductive electronic along with minor resonance effect during electron transfer from olefin to 2 in the rate-limiting step. Additionally, a computational study supports the involvement of stepwise pathways during olefin epoxidation. The ferryl bend due to the bulkier ligand incorporation leads to destabilization of both (Formula presented.) and (Formula presented.) orbitals, leading to a very small quintet–triplet gap and enhanced reactivity for 2 compared to 1. Thus, the present study unveils the role of steric and electronic effects of the ligand towards mechanistic modification during olefin epoxidation.
- Biswas, Jyoti Prasad,Ansari, Mursaleem,Paik, Aniruddha,Sasmal, Sheuli,Paul, Sabarni,Rana, Sujoy,Rajaraman, Gopalan,Maiti, Debabrata
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supporting information
p. 14030 - 14039
(2021/05/11)
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- Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex
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High-valent metal-oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox-active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron-donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high-valent nickel species is subsequently formed to carry out oxo-transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.
- Kim, Soohyung,Jeong, Ha Young,Kim, Seonghan,Kim, Hongsik,Lee, Sojeong,Cho, Jaeheung,Kim, Cheal,Lee, Dongwhan
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supporting information
p. 4700 - 4708
(2021/02/12)
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- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
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Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
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- Bifunctional Metal-Organic Layers for Tandem Catalytic Transformations Using Molecular Oxygen and Carbon Dioxide
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Tandem catalytic reactions improve atom- and step-economy over traditional synthesis but are limited by the incompatibility of the required catalysts. Herein, we report the design of bifunctional metal-organic layers (MOLs), HfOTf-Fe and HfOTf-Mn, consisting of triflate (OTf)-capped Hf6 secondary building units (SBUs) as strong Lewis acidic centers and metalated TPY ligands as metal active sites for tandem catalytic transformations using O2 and CO2 as coreactants. HfOTf-Fe effectively transforms hydrocarbons into cyanohydrins via tandem oxidation with O2 and silylcyanation whereas HfOTf-Mn converts styrenes into styrene carbonates via tandem epoxidation and CO2 insertion. Density functional theory calculations revealed the involvement of a high-spin FeIV (S = 2) center in the challenging oxidation of the sp3 C-H bond. This work highlights the potential of MOLs as a tunable platform to incorporate multiple catalysts for tandem transformations.
- Jiang, Xiaomin,Lan, Guangxu,Lin, Wenbin,Ni, Kaiyuan,Quan, Yangjian,Shi, Wenjie,Song, Yang,Wang, Cheng
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supporting information
p. 16718 - 16724
(2021/10/21)
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- Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
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Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
- McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
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- Self-assembled ionic liquid based organosilica-titania: A novel and efficient catalyst for green epoxidation of alkenes
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A novel titanium-containing self-assembled ionic liquid based hybrid organic-inorganic organosilica (Ti-ILOS) was prepared, characterized and applied as highly effective catalyst for the green epoxidation of alkenes in the presence of hydrogen peroxide as
- Yari, Omolbanin,Elhamifar, Dawood,Shaker, Masoumeh
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- Modification of MnFe2O4 surface by Mo (VI) pyridylimine complex as an efficient nanocatalyst for (ep)oxidation of alkenes and sulfides
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In this current paper, we report a new type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo?molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover frequency for the oxidization of cyclooctene and cyclohexene (10,850 h?1) and thioanisole and dimethyl sulfide (41,250 h?1). The synthesized catalyst was found highly efficient, retrievable and eco-friendly catalyst for the (ep)oxidation of alkenes and sulfides in excellent yields in a short time. Furthermore, the synthesized nanocatalyst can be reused for four runs without apparent loss of its catalytic activity in the oxidation reaction.
- Bouzari, Narges,Bezaatpour, Abolfazl,Babaei, Behnam,Amiri, Mandana,Boukherroub, Rabah,Szunerits, Sabine
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- Immobilization of molybdenum-based complexes on dendrimer-functionalized graphene oxide and their catalytic activity for the epoxidation of alkenes
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Two novel molybdenum-based heterogeneous catalysts immobilized on dendrimer-functionalized graphene oxide via electrostatic interactions (Mo-1) or covalent bonding (Mo-2) are reported. The catalysts show excellent catalysis in epoxidation of alkenes with high conversion, better selectivity and good recyclability. The characteristics were identified by SEM, TEM (EDS-mapping), FT-IR, XRD, and XPS. The cause of the difference between the two catalysts is supported by DFT calculations.
- Cheng, Maosheng,Fan, Zhanfang,Lin, Bin,Liu, Yang,Liu, Yongqing
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- Domino Processes of Arynes Reacting with Three Classes of Nucleophiles for Organic Syntheses
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Synthetic application of arynes is broadened by their reactions with neutral N-, S-, and O-containing nucleophiles to produce three types of compounds. Accordingly, 1,2-dihydroquinolines are synthesized from Schiff bases, alkynes, and arynes through a Diels-Alder reaction. Epoxides are prepared from thioethers and arynes along with aldehydes or ketones through a Johnson-Corey-Chaykovsky reaction. Phenolic ethers are produced from allyl ethers and arynes through a Claisen-type rearrangement. These target molecules, including natural products γ-asarone, asaricin, and a cholesteryl phenolic ether, are formed through reactions initiated by arynes. These new reactions share a prevailing feature of domino processes, which are carried out in a single flask and afford the desired products in good to high yields.
- Hwu, Jih Ru,Panja, Avijit,Gupta, Nitesh K.,Hu, Yu-Chen,Tan, Kui-Thong,Lin, Chun-Cheng,Hwang, Kuo-Chu,Hsu, Ming-Hua,Huang, Wen-Chieh,Tsay, Shwu-Chen
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p. 683 - 693
(2021/01/18)
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- Construction of an Asymmetric Porphyrinic Zirconium Metal-Organic Framework through Ionic Postchiral Modification
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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.
- Berijani, Kayhaneh,Morsali, Ali
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p. 206 - 218
(2021/01/11)
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- Microwave-Assisted Palladium-Catalyzed Reductive Cyclization/Ring-Opening/Aromatization Cascade of Oxazolidines to Isoquinolines
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An efficient palladium-catalyzed reaction of N-propargyl oxazolidines for the construction of 4-substituted isoquinolines under microwave irradiation is developed. This transformation proceeds through a sequential palladium-catalyzed reductive cyclization/ring-opening/aromatization cascade via C-O and C-N bond cleavages of the oxazolidine ring. The practical value of this method has also been explored by conducting a millimole-scale reaction, as well as by transforming the isoquinoline into a key intermediate for the synthesis of a lamellarin analogue.
- Xu, Xianjun,Feng, Huangdi,Van Der Eycken, Erik V.
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p. 6578 - 6582
(2021/09/02)
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- Photocatalytic asymmetric epoxidation oftrans-stilbene with manganese-porphyrin/graphene-oxide nanocomposite and molecular oxygen: axial ligand effect
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An efficient, visible light-driven manganese-porphyrin photocatalyst was developed for the asymmetric epoxidation by molecular oxygen under mild conditions. A Mn-porphyrin complex covalently bonded to graphene oxide (GO) sheets was synthesized and characterized, where chirality is induced by enantiopurel-tartrate (tart), acting either as a counter ion or axial ligand. The heterogeneous photocatalyst GO-[Mn(T2PyP)(tart)](tart) showed an excellent epoxide selectivity of 100% toward the enantioselective epoxidation oftrans-stilbene (ee 100%) in the presence of imidazole under irradiation with a white LED light source. An imidazole molecule hydrogen bonded to the high-valent manganese-oxo intermediate and (tartrate)?counter ion seems to be responsible for substantially enhancing the enantioselectivity of the catalyst. Also, an imidazole molecule coordinated to the metal centre is probably involved in the increased catalytic activity. With immobilized manganese porphyrin as photocatalyst, significant improvements in rate and enantioselectivity were attained by simply adding imidazole as an axial ligand and a hydrogen bond donor intrans-stilbene epoxidation. At the end of the reaction, GO-[Mn(T2PyP)(tart)](tart) was readily separated by filtration and reused for subsequent runs without any loss of its activity and enantioselectivity, resulting in a total turnover number (TON) of 3000.
- Ahadi, Elahe,Hosseini-Monfared, Hassan,Janiak, Christoph,Spie?, Alex
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p. 3290 - 3302
(2020/06/09)
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- Triton X-100 functionalized Cu(II) dihydrazone based complex immobilized on Fe3O4@dopa: A highly efficient catalyst for oxidation of alcohols, alkanes, and sulfides and epoxidation of alkenes
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Here, we have presented a protocol for green synthesis, characterization, and catalytic application of TX100/Fe3O4@dopa@CuL (FDCTX) magnetically separable nanoparticles. Fe3O4@dopa@CuL (FDC) was synthesized using a four-step procedure: (i) synthesis of a dihydrazone derivative, (ii) reaction of the dihydrazone derivative with copper perchlorate salt to generate a copper complex of the dihydrazone derivative, (iii) immobilization of the complex onto Fe3O4@dopa to generate FDC, and (iv) coating of FDC with surfactant Triton X-100. The as-synthesized homogeneous complex was well characterized using UV–Vis., Fourier-transform infrared (FT-IR), electrospray ionization–mass spectrometry, and single-crystalX-ray techniques. Single-crystalX-ray analysis revealed the tetranuclear framework of the complex. The heterogeneous nanoparticles (FDCTX) were characterized using FT-IR, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersiveX-ray spectroscopy, magnetic hysteresis, and dynamic light scattering techniques. Finally, both the homogeneous and heterogeneous catalysts were utilized for efficient oxidation of alcohols, alkanes, and sulfides and epoxidation of alkenes. A most probable mechanism for the oxidation reaction is proposed at the end of the article.
- Chakraborty, Tonmoy,Mondal, Rimpa,Ghanta, Rinku,Chakraborty, Aratrika,Chattopadhyay, Tanmay
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- Cu(ii)Cl2containing bispyridine-based porous organic polymer support preparedviaalkyne-azide cycloaddition as a heterogeneous catalyst for oxidation of various olefins
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A new type of porous organic polymer (POP) based heterogeneous catalystCu-POPwas prepared by immobilizing Cu(ii)Cl2into bpy containing POP preparedviaalkyne-azide cycloaddition. This new catalyst showed efficient catalytic activities and outstanding reusability. Remarkably, one batch ofCu-POPwas continuously used for all olefins without losing its activity by simply washing.
- Choi, Hye Min,Lee, Suk Joong,Yoon, Jongho
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supporting information
p. 9149 - 9152
(2020/06/17)
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- Biochar as supporting material for heterogeneous Mn(II) catalysts: Efficient olefins epoxidation with H2O2
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A novel type of hybrid catalytic materials [MnII-L?BC] has been developed using biochar (BC) as support material for covalent grafting of a MnII Schiff-base catalyst (MnII-L). The hybrid [MnII-L?BC] materials have been evaluated for an important catalytic process, epoxidation of olefins using H2O2 as oxidant. A number of different substrates were used, with cyclohexene achieving the highest yields. When compared to the non-grafted, homogeneous MnII-L, the hybrid catalysts [MnII-L?BC] show a significant enhancement of the catalytic efficiency i.e. as documented by the increase of Turnover Numbers (TONs) (826 for [MnII-L-SS550ox] and 822 for [MnII-L-SW550ox]) and Turnover Frequencies (TOFs) (551 h?1 for [MnII-L-SS550ox] and 411 h?1 for [MnII-L-SW550ox]). The interfacial catalytic mechanism and the role of the BC support have been analyzed by Raman and Electron Paramagnetic Resonance spectroscopies. Based on these data we discuss a mechanism where the high efficiency of the hybrid materials involves the biochar carbon layers acting as promoters of the substrate and products kinetics. To a broader context, this work exemplifies that biochar-based hybrid materials are potent for oxidative catalysis technologies.
- Borges Regitano, Jussara,Deligiannakis, Yiannis,Gemenetzi, Aikaterini,Louloudi, Maria,Mavrogiorgou, Alexandra,Pierri, Leticia
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- Manganese(Ⅲ)-iodosylbenzene complex, preparation method thereof and oxidant comprising the same
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The present invention relates to a manganese(III)-iodosylbenzene complex, a preparation method thereof, and an oxidant comprising the same. The manganese(III)-iodosylbenzene complex provided in one aspect of the present invention has an effect of inducing a hydrogen atom abstraction (HAA) reaction of cyclohexadiene, dihydroanthracene and xanthine, and an oxygen atom transfer (OAT) reaction of thioanisole and stilbene with excellent electrophilic reactivity. The manganese(III)-iodosylbenzene complex is represented by a compound of formula 1: [Mn^III(L)(OIPh)(OH)]^2+.COPYRIGHT KIPO 2020
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Paragraph 0130; 0143-0147; 0153-0166
(2020/09/22)
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- Method for synthesizing epoxy compound by catalyzing epoxidation of olefin with nano-alumina
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The invention belongs to the field of organic synthesis and catalysis, and discloses a method for synthesizing an epoxy compound by catalyzing epoxidation of olefin with nano-alumina. The method comprises the following steps: adding a solvent, olefin, nano-alumina and fatty aldehyde into a reactor to obtain a mixed solution, vacuumizing a reaction container, introducing oxygen, heating and stirring for a reaction by taking olefin as a raw material, taking nano-alumina as a catalyst and taking fatty aldehyde as a reducing agent, obtaining a reaction solution after the reaction is finished, andseparating and purifying the reaction solution to obtain the epoxy compound. The method has the advantages of cheap and easily available in the catalyst, easy to obtain, mild in reaction condition, wide in substrate applicability and safe and simple to operate, and has a potential industrial application prospect.
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Paragraph 0117-0125
(2020/06/17)
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Post-synthetic Modification of DUT-5-based Metal Organic Frameworks for the Generation of Single-site Catalysts and their Application in Selective Epoxidation Reactions
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New single-site catalysts based on mixed-linker metal-organic frameworks with DUT-5 structure, which contain immobilized Co2+, Mn2+ and Mn3+ complexes, have successfully been synthesized via post-synthetic modification. 2,
- Yildiz, Ceylan,Kutonova, Ksenia,O?wald, Simon,Titze-Alonso, Alba,Bitzer, Johannes,Br?se, Stefan,Kleist, Wolfgang
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p. 1134 - 1142
(2020/01/21)
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- Formal [3+2] cycloaddition reactions of electron-rich aryl epoxides with alkenes under Lewis acid catalysis affording tetrasubstituted tetrahydrofurans
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We report on the regio- and stereoselective synthesis of tetrahydrofurans by reaction between epoxides and alkenes in the presence of a Lewis acid. This is an unprecedented formal [3+2] cycloaddition reaction between an epoxide and an alkene. The chemical reaction represents a very concise synthesis of tetrahydrofurans from accessible starting compounds.
- Macías-Villamizar, Víctor E.,Cuca-Suárez, Luís,Rodríguez, Santiago,González, Florenci V.
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supporting information
(2020/02/18)
-
- Method for catalyzing epoxidation of olefin
-
The invention discloses a method for catalyzing epoxidation of olefin. According to the method, an olefin compound is used as a raw material, hydrogen peroxide, peracetic acid, tert-butyl hydroperoxide and m-chloroperoxybenzoic acid are used as oxidants, a metalloporphyrin-based super-cross-linked polymer is used as a catalyst, and a catalytic reaction is carried out at a reaction temperature of 25-80 DEG C to obtain an epoxide at high selectivity. The method has the advantages of simple process, high yield, catalyst recyclability, mild conditions and the like.
- -
-
Paragraph 0035-0036
(2020/04/17)
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- Immobilization of (tartrate-salen)Mn(III) polymer complexes into SBA-15 for catalytic asymmetric epoxidation of alkenes
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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.
- Jia, Yihong,ALOthman, Zeid A.,Liang, Rui,Cha, Shuangshuang,Li, Xiaoyong,Ouyang, Weiyi,Zheng, Aqun,Osman, Sameh M.,Luque, Rafael,Sun, Yang
-
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- New chiral stationary phases for liquid chromatography based on small molecules: Development, enantioresolution evaluation and chiral recognition mechanisms
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Recently, we reported the development of new chiral stationary phases (CSPs) for liquid chromatography (LC) based on chiral derivatives of xanthones (CDXs). Based on the most promising CDX selectors, 12 new CSPs were successfully prepared starting from suitable functionalized small molecules including xanthone and benzophenone derivatives. The chiral selectors comprising one, two, three, or four chiral moieties were covalently bonded to a chromatographic support and further packed into LC stainless-steel columns (150?×?2.1?mm I.D.). The enantioselective performance of the new CSPs was evaluated by LC using different classes of chiral compounds. Specificity for enantioseparation of some CDXs was observed in the evaluation of the new CSPs. Besides, assessment of chiral recognition mechanisms was performed by computational studies using molecular docking approach, which are in accordance with the chromatographic parameters. X-Ray analysis was used to establish a chiral selector 3D structure.
- Phyo, Ye' Zaw,Teixeira, Joana,Tiritan, Maria Elizabeth,Cravo, Sara,Palmeira, Andreia,Gales, Luís,Silva, Artur M.S.,Pinto, Madalena M.M.,Kijjoa, Anake,Fernandes, Carla
-
-
- Dendrimer crown-ether tethered multi-wall carbon nanotubes support methyltrioxorhenium in the selective oxidation of olefins to epoxides
-
Benzo-15-crown-5 ether supported on multi-wall carbon nanotubes (MWCNTs) by tethered poly(amidoamine) (PAMAM) dendrimers efficiently coordinated methyltrioxorhenium in the selective oxidation of olefins to epoxides. Environmentally friendly hydrogen peroxide was used as a primary oxidant. Up to first and second generation dendrimer aggregates were prepared by applying a divergent PAMAM methodology. FT-IR, XRD and ICP-MS analyses confirmed the effective coordination of methyltrioxorhenium by the benzo-15-crown-5 ether moiety after immobilization on MWCNTs. The novel catalysts converted olefins to the corresponding epoxides in high yield without the use of Lewis base additives, or anhydrous hydrogen peroxide, the catalyst being stable for more than six oxidative runs. In the absence of the PAMAM structure, the synthesis of diols largely prevailed.
- Bizzarri, Bruno Mattia,Botta, Lorenzo,Crucianelli, Marcello,Fanelli, Angelica,Ferella, Francesco,Gontrani, Lorenzo,Sadun, Claudia,Saladino, Raffaele
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p. 17185 - 17194
(2020/05/18)
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- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- An effective strategy for creating asymmetric MOFs for chirality induction: A chiral Zr-based MOF for enantioselective epoxidation
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Recently the construction of chiral MOFs (CMOFs) has been very challenging and complex. For the first time, we synthesized a chiral Zr-based MOF with l-tartaric acid by solvent-assisted ligand incorporation (SALI). We show that a CMOF can be postsynthetically generated by a simple method: incorporating chiral carboxylic groups on the achiral NU-1000. The post-synthesized chiral NU-1000 was used as an asymmetric support for producing a chiral catalyst with molybdenum catalytic active centers as Lewis acid sites. Enantioselective epoxidation of various prochiral alkens to epoxids by using [C-NU-1000-Mo] is comparable to that using other asymmetric homogeneous and heterogeneous catalysts, along with high enantiomeric excess and selectivity to epoxide (up to 100%). The CMOF could be reused in the styrene oxidation after five cycles without substantial deterioration in the CMOF crystallinity or catalytic performance.
- Berijani, Kayhaneh,Morsali, Ali,Hupp, Joseph T.
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p. 3388 - 3397
(2019/07/10)
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- Dual activity of durable chiral hydroxyl-rich MOF for asymmetric catalytic reactions
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The quest to prepare of asymmetric heterogeneous catalysts with both effective Br?nsted acid sites (BASs) and Lewis acid sites is very significant challenge. Herein, we report the construction of a chiral metal-organic framework with two kinds of catalytic active sites (Lewis acid/Br?nsted acid). It contains coordinative unsaturation metal centers and chiral functional groups that have cooperation in the catalytic activity. In the synthesized CMOF, the chiral decoration of metal node was performed through the practical method: anions exchange hypothesis (post-synthetic exchange). For this aim, the elimination of framework fluorides happened by using the enantiopure auxiliary anions (L-(+)-tartrate anion (tart?)) that led to a chiral cationic MOF with eventual chemical formula [Cr3tart(H2O)2O(bdc)3]. XRD, BET, 1H NMR, SEM and EDX were employed to characterize of the present CMIL. Despite the chiral tartrate anions generate a chiral environment, they have main role in the activating of epoxide ring due to hydrogen-bonding interaction. Experiments show that the enantiopure tartrate-functionalized MIL-101(Cr) as a green asymmetric catalyst has the considerable performance in the enantioselective reactions due to chiral modified surface without remarkable loss in activity.
- Berijani, Kayhaneh,Morsali, Ali
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- A novel homochiral metal-organic framework with an expanded open cage based on (: R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl: synthesis, X-ray structure and efficient HPLC enantiomer separation
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A new homochiral metal-organic framework (MOF) with an expanded open cage based on the (R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl ligand was synthesized and utilized as a novel chiral stationary phase for high-performance liquid chromatography. Twelve racemates including sec-alcohols, sulfoxides, epoxides, lactone, 1,3-dioxolan-2-one, and oxazolidinone were used as analytes for evaluating the separation properties of the chiral-MOF-packed column. Experimentally, the homochiral MOF offered good molecular recognition ability, which suggests good prospects for the application of chiral MOFs as stationary phases for enantioseparation.
- Tanaka, Koichi,Kawakita, Tomohiro,Morawiak, Maja,Urbanczyk-Lipkowska, Zofia
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p. 487 - 493
(2019/01/21)
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- HPLC with cellulose Tris (3,5-DimethylPhenylcarbamate) chiral stationary phase: Influence of coating times and coating amount on chiral discrimination
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Coating cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC) on silica gels with large pores have been demonstrated as an efficient way for the preparation of chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). During the process, a number of parameters, including the type of coating solvent, amount of coating, and the method for subsequent solvent removing, have been proved to affect the performance of the resultant CSPs. Coating times and the concentration of coating solution, however, also makes a difference to CSPs' performance by changing the arrangement of cellulose derivatives while remaining the coating amount constant, have much less been studied before, and thereby, were systematically investigated in this work. Results showed that CSPs with more coating times exhibited higher chiral recognition and column efficiency, suggesting that resolution was determined by column efficiency herein. Afterwards, we also investigated the effect of coating amount on the performance of CSPs, and it was shown that the ability of enantio-recognition did not increase all the time as the coating amount; and four of seven racemates achieved best resolution when the coating amount reached to 18.37%. At the end, the reproducibility of CDMPC-coated CSPs were further confirmed by two methods, ie, reprepared the CSP-0.15-3 and reevaluated the effect of coating times.
- Wei, Qiuhong,Su, Hongjiu,Gao, Diannan,Wang, Shudong
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p. 164 - 173
(2019/01/18)
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- Homochiral Metal-Organic Frameworks for Enantioselective Separations in Liquid Chromatography
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Selective separation of enantiomers is a substantial challenge for the pharmaceutical industry. Chromatography on chiral stationary phases is the standard method, but at a very high cost for industrial-scale purification due to the high cost of the chiral stationary phases. Typically, these materials are poorly robust, expensive to manufacture, and often too specific for a single desired substrate, lacking desirable versatility across different chiral analytes. Here, we disclose a porous, robust homochiral metal-organic framework (MOF), TAMOF-1, built from copper(II) and an affordable linker prepared from natural l-histidine. TAMOF-1 has shown to be able to separate a variety of model racemic mixtures, including drugs, in a wide range of solvents of different polarity, outperforming several commercial chiral columns for HPLC separations. Although not exploited in the present article, it is worthy to mention that the preparation of this new material is scalable to the multikilogram scale, opening unprecedented possibilities for low-energy chiral separation at the industrial scale.
- Corella-Ochoa, M. Nieves,Tapia, Jesús B.,Rubin, Heather N.,Lillo, Vanesa,González-Cobos, Jesús,Nú?ez-Rico, José Luis,Balestra, Salvador R.G.,Almora-Barrios, Neyvis,Lledós, Marina,Gu?ll-Bara, Arnau,Cabezas-Giménez, Juanjo,Escudero-Adán, Eduardo C.,Vidal-Ferran, Anton,Calero, Sofiá,Reynolds, Melissa,Martí-Gastaldo, Carlos,Galán-Mascarós, José Ramón
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p. 14306 - 14316
(2019/10/11)
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- Unified Mechanism of Oxygen Atom Transfer and Hydrogen Atom Transfer Reactions with a Triflic Acid-Bound Nonheme Manganese(IV)-Oxo Complex via Outer-Sphere Electron Transfer
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Outer-sphere electron transfer from styrene, thioanisole, and toluene derivatives to a triflic acid (HOTf)-bound nonheme Mn(IV)-oxo complex, [(N4Py)MnIV(O)]2+-(HOTf)2 (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), has been shown to be the rate-determining step of different types of redox reactions such as epoxidation, sulfoxidation, and hydroxylation of styrene, thioanisole, and toluene derivatives, respectively, by [(N4Py)MnIV(O)]2+-(HOTf)2. The rate constants of HOTf-promoted epoxidation of all styrene derivatives with [(N4Py)MnIV(O)]2+ and electron transfer from electron donors to [(N4Py)MnV(O)]2+ exhibit a remarkably unified correlation with the driving force of outer-sphere electron transfer in light of the Marcus theory of electron transfer. The same electron-transfer driving force dependence is observed in the oxygen atom transfer from [(N4Py)MnIV(O)]2+-(HOTf)2 to thioanisole derivatives as well as in the hydrogen atom transfer from toluene derivatives to [(N4Py)MnIV(O)]2+-(HOTf)2. Thus, mechanisms of oxygen atom transfer (epoxidation and sulfoxidation) reactions of styrene and thioanisole derivatives and hydrogen atom transfer (hydroxylation) reactions of toluene derivatives by [(N4Py)MnIV(O)]2+-(HOTf)2 have been unified for the first time as the same reaction pathway via outer-sphere electron transfer, followed by the fast bond-forming step, which exhibits the singly unified electron-transfer driving force dependence of the rate constants as outer-sphere electron-transfer reactions. In the case of the epoxidation of cis-stilbene by [(N4Py)MnIV(O)]2+-(HOTf)2, the isomerization of cis-stilbene radical cation to trans-stilbene radical cation occurs after outer-sphere electron transfer from cis-stilbene to [(N4Py)MnIV(O)]2+-(HOTf)2 to yield trans-stilbene oxide selectively, which is also taken as evidence for the occurrence of electron transfer in the acid-catalyzed epoxidation.
- Lee, Yong-Min,Kim, Surin,Ohkubo, Kei,Kim, Kyung-Ha,Nam, Wonwoo,Fukuzumi, Shunichi
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p. 2614 - 2622
(2019/03/04)
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- Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts
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Over the past two decades, there have been major developments in the transition iron-catalyzed selective oxidation of alkenes to epoxides; a common structure found in drug, isolated natural products, and fine chemicals. Many of these approaches have enabled highly efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefin epoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6], various aromatic and aliphatic alkenes were successfully transformed into the corresponding epoxides with excellent yields as well as chemo- and stereo-selectivity. This catalytic system possesses the advantages of being able to avoid the use of expensive, toxic, air/moisture sensitive and commercially unavailable organic ligands. The generality of this methodology is simple to operate and exhibits high catalytic activity as well as excellent stability, which gives it the potential to be used on an industrial scale, and maybe opens a way for the catalytic oxidation reaction via inorganic-ligand coordinated iron catalysis.
- Zhou, Zhuohong,Dai, Guoyong,Ru, Shi,Yu, Han,Wei, Yongge
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supporting information
p. 14201 - 14205
(2019/10/02)
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- Designing of a magnetically separable Fe3O4@dopa@ML nano-catalyst for multiple organic transformations (epoxidation, reduction, and coupling) in aqueous medium
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A copper(II) macrocyclic Schiff base complex (ML) was synthesized by condensation between 2,2-dimethylpropane-1,3-diammine and 2,6-diformyl-4-butylphenol with the aim to modify the surface of widely used magnetically separable nanocatalyst Fe3O
- Dasgupta, Sanchari,Chatterjee, Sourav,Chattopadhyay, Tanmay
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p. 550 - 568
(2019/02/26)
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- Conglomerated system of Ag nanoparticles decorated Al2O3 supported cobalt and copper complexes with enhanced catalytic activity for oxidation reactions
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In this study, our aim is to increase the effectiveness of heterogeneous catalysts by reducing its drawback. For this purpose we have developed a new method to synthesize heterogeneous catalyst by dispersion of Silver nanoparticles onto Alumina supported cobalt and copper Schiff base complexes (AgNPs-Al2O3@ML).Initially Schiff base and its corresponding Co (III) complex, (CoL) and Cu (II) complex, (CuL)(L = Schiff base) were synthesized. Both the complexes were immobilized on Al2O3 to generate Al2O3@CoL (HT1) and Al2O3@CuL (HT2). Finally, Silver was dispersed onto both the heterogeneous complexes to generate our desired heterogeneous catalyst Ag NPs-Al2O3@CoL (AgHT1) and Ag NPs-Al2O3@CuL (AgHT2).A hike in BET surface area from HT1 to AgHT1 highlighted the fruitfulness of decoration of Ag NPs onto HT1. FESEM studies of AgHT1 and AgHT2 reveal the formation of pyramidal type silver nanoparticle onto HT1 and HT2. The catalytic ability of CoL, CuL (homogeneous catalyst), HT1, HT2 and AgHT1, AgHT2 (heterogeneous catalyst) were investigated by enrolling it on oxidation of alcohols, alkanes and epoxidation of alkenes using H2O2 as oxidant. Among the four heterogeneous catalysts AgHT1 showed highest activity. Finally a plausible mechanism has been put forward to elucidate the role of each substituent of the catalytic system. The heterogeneous catalysts HT1, HT2, AgHT1 and AgHT2 can be reused up to six times without any significant loss in its catalytic activity.
- Chakraborty, Tonmoy,Chakraborty, Aratrika,Maity, Suvendu,Das, Debasis,Chattopadhyay, Tanmay
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p. 104 - 113
(2018/11/21)
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- Tailoring chemoenzymatic oxidation: Via in situ peracids
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Epoxidation chemistry often suffers from the challenging handling of peracids and thus requires in situ preparation. Here, we describe a two-phase enzymatic system that allows the effective generation of peracids and directly translate their activity to the epoxidation of olefins. We demonstrate the approach by application to lipid and olefin epoxidation as well as sulfide oxidation. These methods offer useful applications to synthetic modifications and scalable green processes.
- Re, Rebecca N.,Proessdorf, Johanna C.,La Clair, James J.,Subileau, Maeva,Burkart, Michael D.
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supporting information
p. 9418 - 9424
(2019/11/14)
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- Trapping of a Highly Reactive Oxoiron(IV) Complex in the Catalytic Epoxidation of Olefins by Hydrogen Peroxide
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The generation of a nonheme oxoiron(IV) intermediate, [(cyclam)FeIV(O)(CH3CN)]2+ (2; cyclam=1,4,8,11-tetraazacyclotetradecane), is reported in the reactions of [(cyclam)FeII]2+ with aqueous hydrogen peroxide (H2O2) or a soluble iodosylbenzene (sPhIO) as a rare example of an oxoiron(IV) species that shows a preference for epoxidation over allylic oxidation in the oxidation of cyclohexene. Complex 2 is kinetically and catalytically competent to perform the epoxidation of olefins with high stereo- and regioselectivity. More importantly, 2 is likely to be the reactive intermediate involved in the catalytic epoxidation of olefins by [(cyclam)FeII]2+ and H2O2. In spite of the predominance of the oxoiron(IV) cores in biology, the present study is a rare example of high-yield isolation and spectroscopic characterization of a catalytically relevant oxoiron(IV) intermediate in chemical oxidation reactions.
- Engelmann, Xenia,Malik, Deesha D.,Corona, Teresa,Warm, Katrin,Farquhar, Erik R.,Swart, Marcel,Nam, Wonwoo,Ray, Kallol
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supporting information
p. 4012 - 4016
(2019/02/20)
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- Olefins oxidation with molecular O2 in the presence of chiral Mn (III) salen complex supported on magnetic CoFe2O4@SiO2@CPTMS
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In the present study, CoFe2O4@SiO2@CPTMS nanocomposite was synthesized and the homogeneous chiral Mn-salen complex was anchored covalently onto the surface of CoFe2O4@SiO2@CPTMS nanocomposite. The heterogeneous Mn-salen magnetic nanocatalyst (CoFe2O4@SiO2@CPTMS@ chiral Mn (III) Complex) was characterized by different techniques including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Then, the aerobic enantioselective oxidation of olefins to the corresponding epoxide was investigated in the presence of magnetic chiral CoFe2O4@SiO2@Mn (III) complex at ambient conditions within 90?min. The results showed the corresponding products were synthesized with excellent yields and selectivity. In addition, the heterogeneous CoFe2O4@SiO2@ CPTMS@ chiral Mn (III) complex has benefits such as high selectivity and comparable catalytic reactivity with its homogeneous analog as well as mild reaction condition, facile recovery, and recycling of the heterogeneous catalyst.
- Hemmat, Kaveh,Nasseri, Mohammad A.,Allahresani, Ali
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- A mesoporous NNN-pincer-based metal-organic framework scaffold for the preparation of noble-metal-free catalysts
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Through topology-guided synthesis, a Zr-based mesoporous MOF was successfully constructed, adopting a β-cristobalite-type structure. The MOF is embedded with well-arranged terpyridine coordination sites for facile post-synthetic metalation, and can be effectively used as a general scaffold for the preparation of noble-metal-free catalysts. For instance, the scaffolded metal@MOF material exhibits highly efficient catalytic activity for alkene epoxidation and arene borylation.
- Zhang, Yingmu,Li, Jialuo,Yang, Xinyu,Zhang, Peng,Pang, Jiandong,Li, Bao,Zhou, Hong-Cai
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p. 2023 - 2026
(2019/02/19)
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- Iron(II) tetrafluoroborate complexes of new tetradentate C-scorpionates as catalysts for the oxidative cleavage of: Trans-stilbene with H2O2
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Attachment of a 2-methylpyridyl group onto the unique 1-nitrogen atom on nitrogen-confused C-scorpionates with either pyrazol-1-yl or 3,5 dimethylpyrazol-1-yl donors gives two new cis-directing tetradentate-N4 ligands (L and L?). The complexes [(L or L?)Fe(CH3CN)2](BF4)2 (1 or 2) were prepared, fully characterized, and investigated for their ability to catalyse the oxidative cleaveage of trans-stilbene in CH3CN. Complexes 1 and 2 are capable of catalysing stilbene cleavage when H2O2 is used as an oxidant but up to six different products are formed, with CC cleavage products (benzaldehyde and benzoic acid) dominating over four products of oxygen transfer. Catalytic amounts of 1 or 2 enhance the ability for the organic photocatalyst riboflavin tetraacetate to use atmospheric oxygen and blue light irradation (450-460 nm) to selectively cleave stilbene to benzaldehyde. However, when benzaldehyde oxidizes further to benzoic acid, the iron species begin giving increasing amounts of stilbene oxygenation products.
- Wang, Denan,Gardinier, James R.,Lindeman, Sergey V.
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p. 14478 - 14489
(2019/10/11)
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- Method for preparing epoxide by one-pot olefin aerobic epoxidation
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The invention relates to a method for preparing an epoxide by one-pot olefin aerobic epoxidation, and belongs to the technical field of organic synthesis. An olefin, an alkyl aromatic compound and analkali are added into a solvent, or an olefin, an alkyl aromatic compound and an alkali are directly mixed; the temperature is raised to 70-160 DEG C in an air or oxygen atmosphere; reacting is carried out for 1-48 hours; and the olefin is directly oxidized into the corresponding epoxide in the presence of the alkyl aromatic compound, the alkali and air (or oxygen), wherein the yield is up to 99%.In the reaction process, the generated alkyl peroxide is generated in situ and consumed in situ, so that the concentration of the alkyl peroxide is kept at a lower level; and generated alkyl peroxy free radicals can also react with the olefin to further generate the peroxide, and efficiency is improved. The method has the advantages of simple operation, mild conditions, low raw material cost andno need of special complex equipment, and has a good industrial application prospect.
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Paragraph 0074-0075
(2020/01/03)
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- A practical innovative method for highly selective oxidation of alkenes and alkanes using Fe (III) and Mn (III) porphyrins supported onto multi-wall carbon nanotubes as reusable heterogeneous catalysts
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Functionalized multi-walled carbon nanotubes were used for covalent immobilization of meso-tetrakis(4-carboxyphenyl) porphyrinatoiron (III) chloride [Fe (TCPP)Cl] and meso-tetrakis(4-carboxyphenyl) porphyrinatomanganese (III) acetate [Mn (TCPP)OAc]. The full characterization of the hybrid porphyrinic nanomaterials, by Fourier transform-infrared and UV–Vis spectroscopy, transmission electron microscopy, thermogravimetry and flame atomic absorption spectrometry is described. The oxidation of alkenes and alkanes with molecular oxygen as green oxidant in the presence of Mn- and Fe-catalysts has been studied in a comparative manner. The Fe-catalyst was shown to have higher catalytic activity compared with the Mn-catalyst. In addition, both separable solid catalysts can be recovered and reused at least 10 times along with good yields.
- Rayati, Saeed,Nafarieh, Parinaz
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- Iron-Decorated, Guanidine Functionalized Metal-Organic Framework as a Non-heme Iron-Based Enzyme Mimic System for Catalytic Oxidation of Organic Substrates
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A novel porous functionalized metal-organic framework (MOF) as a non-heme iron-based enzyme mimic system was achieved via two-step post-synthetic modification of the MIL-101(Cr)-NH2, and characterized by FT-IR, PXRD, TGA, SEM, EDS, CHN, BET surface area, and ICP-OES analyses. This new modified MOF (MIL-101(Cr)-guanidine-Fe) has been demonstrated to be a highly efficient, active, and reusable catalyst for oxidation of various organic substrates, including alcohols, alkenes and alkyl arenes at room temperature using H2O2 as an oxidant. Graphical Abstract: [Figure not available: see fulltext.].
- Shaabani, Ahmad,Mohammadian, Reza,Farhid, Hassan,Karimi Alavijeh, Masoumeh,Amini, Mostafa M.
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p. 1237 - 1249
(2019/03/13)
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- Vanadyl β-tetrabromoporphyrin: Synthesis, crystal structure and its use as an efficient and selective catalyst for olefin epoxidation in aqueous medium
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We hereby report the synthesis, characterization and catalytic applications in the epoxidation of alkenes by a vanadyl porphyrin having bulky bromo substituents at the β-positions viz. vanandyltetrabromotetraphenylporphyrin (1). The synthesized porphyrin was characterized by various spectroscopic techniques like UV-visible, FT-IR, EPR, MALDI-TOF mass spectrometry and single crystal X-ray analysis. Porphyrin 1 has a nonplanar structure as indicated by its X-ray structure, DFT and electrochemical studies. 1 was analyzed for its catalytic application in the epoxidation of various alkenes. The catalytic reactions were carried out in CH3CN/H2O mixture in 3:1 (v/v) ratio. 1 displayed good efficiency in terms of mild reaction conditions, lower reaction temperature and minimal catalyst amount consumption. 1 exhibited excellent selectivity, high conversion efficiency and huge TOF (7600-9800 h-1) in a significantly low reaction time of 0.5 h. Catalyst 1 was regenerated at the end of various catalytic cycles making it reusable and industrially important.
- Dar, Tawseef Ahmad,Tomar, Reshu,Mian, Rasel Mohammad,Sankar, Muniappan,Maurya, Mannar Ram
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p. 10405 - 10413
(2019/04/10)
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- Retro-Corey-Chaykovsky Epoxidation: Converting Geminal Disubstituted Epoxides to Ketones
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Corey-Chaykovsky epoxidation has been widely applied in the conversion of aldehydes and ketones to epoxides with sulfonium and sulfoxonium ylides. The reverse transformation is realized for conversion of geminal disubstituted epoxides to ketones in the presence of DABCO in refluxing mesitylene. The method is a weak basic transformation from epoxides to ketones with loss of a methylene group and can be applied as an alternative strategy of the acid-catalyzed Meinwald rearrangement or oxidation for conversion of epoxides to carbonyl compounds.
- Li, Siqi,Li, Pingfan,Xu, Jiaxi
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- Method for directly synthesizing epoxy compound from benzyl bromine compound
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The invention discloses a method for directly synthesizing an epoxy compound from a benzyl bromine compound. According to the method, by using a benzyl bromine compound as a reactant and dimethyl sulfoxide as an oxidizing agent, an epoxy compound is directly synthesized under the action of a solvent and alkali. The synthetic route of the method is as follows: the benzyl bromine compound is dissolved in a reaction solvent to obtain A; the oxidizing agent dimethyl sulfoxide and alkali are added into the A and a reaction is carried out to obtain the epoxy compound. The method is simple and is convenient to operate; the reaction condition is mild; the reaction process is easy to control; the reaction process is safe and environmentally-friendly; the reaction reagents are cheap and easily available; and the reaction yield is high.
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Paragraph 0038-0044; 0122-0127
(2019/08/30)
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- Collaborative effect of Mn-porphyrin and mesoporous SBA-15 in the enantioselective epoxidation of olefins with oxygen
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The rational design of heterogeneous, low cost transition metal complexes that can catalyze olefin with high enantioselectivity and activity has been a challenging goal for the synthetic chemist. In this study a chiral ion pair strategy was used for the synthesis of a biomimetic efficient manganese-tetrapyridylporphyrin (H2TPyP) catalyst for the asymmetric epoxidation of olefins with O2. Complex Mn-TPyP was covalently linked to mesoporous SBA-15 in heme-type environments and its counter ion was replaced by L-tartrate anion (SBA15-[Mn(TPyP)TA]). Chiral and achiral homogeneous analogous of Mn-TPyP were also prepared. The Mn-porphyrin confined in nanoreactors of SBA-15 exhibited enhanced activity (TOF = 652 h?1) and enantiomeric excess (ee 93%) compared with the value obtained when the same chiral catalyst functioned in homogeneous solution (TOF 97 h?1 and ee 83%) in the oxidation of 1-decene with O2/isobutyraldehyde. The high specific surface area, uniformly sized pore channels and site isolated active centers of the catalyst may contribute to the high activity and enantioselectivity. SBA15-[Mn(TPyP)TA] was structurally stable and could be recycled for repeated use. Total turnover number in the oxidation of styrene after five cycles was 47,400 with 86% epoxide selectivity and ee 86%.
- Berijani, Kayhaneh,Hosseini-Monfared, Hassan
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p. 113 - 120
(2017/11/10)
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- Enhanced enantioselective oxidation of olefins catalyzed by Mn-porphyrin immobilized on graphene oxide
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An efficient enantioselective heterogeneous catalyst, GO-[Mn(TPyP)tart], was prepared by covalent attachment of Mn(III) complex of H2TPyP via the propyl linkage to graphene oxide (GO) nanosheet and using chiral tartrate counter ion. The catalyst was characterized by Fourier transform infrared (FT-IR), diffuse reflectance ultraviolet–visible (DR UV–Vis) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and thermogravimetric analysis (TGA). The graphene-supported Mn-porphyrin showed higher activity for the enantioselective epoxidation of unfunctionalized olefins with molecular oxygen in the presence of isobutyraldehyde. It could be recovered easily and reused in asymmetric oxidation of styrene precursor in a five-step sequence without any considerable loss of its catalytic activity and selectivity. The obtained optically epoxide selectivities were achieved in 86% to 100%.
- Berijani, Kayhaneh,Farokhi, Afsaneh,Hosseini-Monfared, Hassan,Janiak, Christoph
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p. 2202 - 2210
(2018/04/02)
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- Manganes-Porphyrin as Efficient Enantioselective Catalyst for Aerobic Epoxidation of Olefins
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A chiral manganese porphyrin, [Mn(TCPP-Ind)Cl], was synthesized using cis-1-amino-2-indanol substituent. It showed remarkable catalytic activity and enantioselectivity in the epoxidation of olefins with O2/RCHO. Terminal olefins and styrene derivatives were successfully oxidized (> 99% ee). TON of 73,000 was achieved in the epoxidation of α-methylstyrene after five times recycling. Graphical Abstract: [Figure not available: see fulltext.].
- Farokhi, Afsaneh,Berijani, Kayhaneh,Hosseini-Monfared, Hassan
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p. 2608 - 2618
(2018/06/14)
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