Jacobsen Catalyst Research Articles

Investigation and Comparison of Catalytic Methods to Produce Green CO2-Containing Monomers for Polycarbonates

The preparation of CO2-containing polymers with improved degradation properties is still very challenging. An elegant method for preparing these polymers is to use CO2-containing monomers in ring-opening polymerizations (ROP) which are particularly gentle and energy-saving methods. However, cyclic carbonates are required for this which are not readily available. This paper therefore aims to present the optimization and comparison of two synthesis methods to obtain cyclic carbonates for ROP. Within this work, cyclic styrene carbonate was synthesized from readily available raw materials by using a Jacobsen catalyst for the reaction of styrene oxide and carbon dioxide or an organocatalyst for the transesterification of methyl carbonate with 1-phenyl-1,2-ethanediol. The latter performed with 100% selectivity to the desired styrene carbonate, which was succesfully tested in ROP, producing an amorphous thermoplastic polymer with a TG of 185 °C.

Construction of highly permeable organic solvent nanofiltration membrane via β-cyclodextrin assisted interfacial polymerization

As the key of organic solvent nanofiltration (OSN) technology, OSN membranes could effectively retain small molecules with molecular weight between 200 and 1000 Dalton (Da), but they still face some problems such as low solvent permeance. In this work, we fabricated a poly(amide-ester) selective layer on polyimide substrate surface by introducing β-cyclodextrin (β-CD) into the aqueous phase solution to assist the interfacial polymerization reaction between m-phenylenediamine (MPD) and trimesoyl chloride (TMC), followed by cross-linking and solvent activation treatment. Thus, we successfully fabricated a kind of thin film composite (TFC) membrane with high selective permeability for OSN. We emphasized that extra-low contents were employed for both MPD and β-CD, which were 0.05 wt% and 50 mg L−1, respectively. The effect of β-CD content on the pore size, surface shape, surface hydrophilicity, surface chemistry, filtration performance, as well as durability performance of the OSN membrane was studied in depth. β-CD endows the selective layer with better hydrophilicity and larger pore size. The optimized OSN membrane possesses a Rhodamine B (RDB, 479 Da) rejection of 99.2 % and an ethanol permeance of 70.6 L m−2 h−1 MPa−1. Furthermore, the optimized OSN membrane remains above 99 % RDB rejection after being immersed in DMF at 25 °C for 1000 h, which demonstrates its superb solvent resistance. Additionally, the optimized OSN membrane exhibits outstanding long-time performance and possesses a rejection of 98 % for Jacobsen catalyst during more than 106 h semi-continuous filtration using Jacobsen catalyst/ethyl acetate solution as feed, indicating its vast potential in the recovery of catalyst.

Electrochemical Epoxidation Catalyzed by Manganese Salen Complex and Carbonate with Boron-Doped Diamond Electrode.

Epoxides are essential precursors for epoxy resins and other chemical products. In this study, we investigated whether electrochemically oxidizing carbonate ions could produce percarbonate to promote an epoxidation reaction in the presence of appropriate metal catalysts, although Tanaka and co-workers had already completed a separate study in which the electrochemical oxidation of chloride ions was used to produce hypochlorite ions for electrochemical epoxidation. We found that epoxides could be obtained from styrene derivatives in the presence of metal complexes, including manganese(III) and oxidovanadium(IV) porphyrin complexes and manganese salen complexes, using a boron-doped diamond as the anode. After considering various complexes as potential catalysts, we found that manganese salen complexes showed better performance in terms of epoxide yield. Furthermore, the substituent effect of the manganese salen complex was also investigated, and it was found that the highest epoxide yields were obtained when Jacobsen's catalyst was used. Although there is still room for improving the yields, this study has shown that the in situ electrochemical generation of percarbonate ions is a promising method for the electrochemical epoxidation of alkenes.

Asymmetric Synthesis of Methoxylated Ether Lipids: A Glyceryl Glycidyl Ether Key Building Block Design, Preparation, and Synthetic Application.

The report describes the preparation and use of a double-C3 building block intended as a head group synthon in the synthesis of saturated, mono-, and polyunsaturated 1-O-alkyl-sn-glycerol type methoxylated ether lipids (MELs). The resulting head piece, an enantiopure isopropylidene-protected glyceryl glycidyl ether diastereomer, was accomplished in 49% yield (max 50%) from a 1:1 diastereomeric mixture obtained from R-solketal and racemic epichlorohydrin after treatment with the Jacobsen (S,S)-Co(III)salen catalyst for the hydrolytic kinetic resolution of terminal epoxides. The diol hydrolytic product obtained in 47% yield from the unwanted diastereomer was reconverted into epoxide with an inversion of configuration in a three-step operation involving a highly regioselective lipase. This enabled the recovery of a substantial amount of diastereopure material after a subsequent treatment with the Jacobsen catalyst to furnish the oxirane head piece in altogether 72% yield of higher than 99% diastereomeric purity. A modified synthesis of a monounsaturated 16:1 MEL confirmed the correct stereochemistry and excellent enantiopurity of the head piece and resulted in a dramatic improvement in yields, efficiency, and economy of the synthesis.

Asymmetric Epoxidation of Unfunctionalized Olefins Catalyzed by Chiral (Pyrrolidine Salen) Mn (III) Complexes with Proline Sidearms

Four (R, R)-3, 4-diaminopyrrolidine-based chiral Salen ligands with L-Boc-N-proline, D-Boc-N-proline, L-proline, D-proline as respective sidearms, as well as their manganese complexes were synthesized and characterized. These Salen-Mn(III) complexes were applied to the asymmetric epoxidations of unfunctionalized olefins with NaClO, and m-CPBA as respective oxidants. The catalysis of the Salen-Mn (III) complexes varied with the change of sidearms. The one with D-Boc-N-proline as a sidearm showed the best asymmetric catalysis among the four chiral manganese complexes, and its catalysis was also better than that of the one with a benzyl sidearm, and comparable with that of Jacobsen's catalyst. Moderate to excellent enantioselectivities and yields were achieved in the asymmetric of various olefins over this complex. The big enhancement of the D-Boc-N-proline sidearm on the enantioselectivity of the asymmetric epoxidation might be ascribed to its large steric hindrance and appropriate configuration, allowing the Boc moiety to be away from the side-on approach pathway of olefins to the active center but near the opposite side one in some degree, thus facilitating the approach of olefins to the active center from one direction.

Rhodamine B oxidation promoted by P450-bioinspired Jacobsen catalysts/cellulose systems.

In this work, we investigated the preparation of P450-bioinspired Mn(iii)-Schiff base complexes supported on DEAE-cellulose ((R,R)-Jacobsen/Cell(NEt2) and (S,S)-Jacobsen/Cell(NEt2), respectively) to oxidize substrates of biological interest. Catalysts were characterized by several physical techniques. UV-Vis spectroscopy with diffuse reflectance (DR/UV-Vis) analysis featured peculiar electronic transitions for both complexes. Fourier transform infrared (FTIR) spectra evidenced the characteristic band of imine groups (HC Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> N) for bioinspired/Cell(NEt2) materials. Immobilization ratios in cellulose fibres were confirmed by atomic absorption spectroscopic (GF-AAS) analyses. Catalytic essays were conducted during rhodamine B (RhB) oxidation. Supported materials attained oxidative yields close to those of homogeneous systems, and cellulose may be stabilizing the active intermediate catalytic species. Reactions may be driven through two different intermediates: MnV(O) and MnIII(O–OH)salen. Homogeneous reactions suggest an asymmetric catalysis. Heterogeneous system reaction yields are similar, and salen complexes anchored on cellulose conformation would interfere on complex intermediate species configuration. The four possible RhB-oxidation products obtained by the reaction with the homogeneous (S,S)-Jacobsen catalyst and meta-chloroperoxybenzoic acid (m-CPBA) system were suggested by 1H NMR analysis, and a catalytic mechanism was proposed.

Retraction statement: Chiral Jacobsen's catalyst immobilized on zinc poly(styrene‐phenylvinylphosphonate)‐phosphate functionalized by diamine as highly efficient and reusable catalyst for alkene epoxidation

Retraction statement: Chiral Jacobsen's catalyst immobilized on zinc poly(styrene‐phenylvinylphosphonate)‐phosphate functionalized by diamine as highly efficient and reusable catalyst for alkene epoxidation

Bioinspired oxidation in cytochrome P450 of isomers orientin and isoorientin using Salen complexes.

Orientin and isoorientin are C-glycosidic flavonoids, considered as markers of some plant species such as Passiflora edulis var. flavicarpa Degener, and reported in the literature to have pharmacological properties. In order to evaluate and characterize the in vitro metabolism of these flavonoids, phase I biotransformation reactions were simulated using Salen complexes. These flavonoids were oxidized separately in biomimetic reactions in different proportions, using one oxidant, m-chloroperbenzoic acid or iodosylbenzene, and one catalyst, the Jacobsen catalyst or [Mn(3-MeOSalen)Cl]. The [Mn(3-MeOSalen)Cl] catalyst was synthesized and characterized using spectrometric techniques. The oxidation potentials of the catalysts were compared. All reactions were monitored and analyzed using ultrahigh-performance liquid chromatography diode-array detection (UHPLC-DAD) and high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). The analysis by UHPLC-DAD and HPLC/MS/MS showed that isoorientin produces more products than orientin and that [Mn(3-MeOSalen)Cl] produces more products than the Jacobsen catalyst. In addition, [Mn(3-MeOSalen)Cl], which has a higher oxidation potential, formed products with the addition of one or two atoms of oxygen, while the Jacobsen catalyst formed compounds with only one added oxygen atom. The products with the addition of one oxygen atom were mainly epoxides, while those with two added oxygens formed an epoxide in the C-ring and incorporated the other oxygen into the glycosidic moiety. The formation of epoxides is common in biomimetic reactions and they may represent a safety risk in medicinal products due to their high reactivity. This study may serve as a basis for subsequent pharmacological and toxicological studies that investigate the presence of these compounds as phase I metabolites, and ensure the safe use of plant products containing orientin as a chemical marker.

Coordination structure of Jacobsen catalyst with N-modified graphene and their electrocatalytic properties for reducing oxygen molecules

Hybridization of the molecular active species with nanoscale materials can serve as a promising route for creating new catalytic nature. Jacobsen catalysts containing Co-O2/N2 structure are well known for converting epoxides to diols. Herein, the Jacobsen catalyst is hybridized with N-doped graphene-based materials. The generation of molecularly dispersed Co-O2/N2-Ngraphene structure on the surface of graphene-based materials is revealed by X-ray absorption, solid-state nuclear magnetic resonance, and X-ray photoelectron spectroscopic measurements. The resulting hybrid shows excellent catalytic performances for electrochemical oxygen reduction reactions (ORR), such as onset (0.91 V) and half-wave (0.80 V) potentials, current density (5.38 mA/cm2), and turnover frequency (0.2 s−1). Characterizations and electrochemical measurements with control samples suggest that the Co-O2/N2-Ngraphene structure is critical for the catalytic properties. Further study with after-cycle-samples highlighted the superior stability of the active species. Theoretical calculation suggests favored ORR reactions of the fifth axial coordination of Co-O2/N2 by pyridinic N dopants.

Asymmetric epoxidation of unfunctionalized olefins with C2-symmetrical diphenol-derived axially coordinated homogeneous chiral bi-Mn(III) salen complexes

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 <10 min, and conversions up to >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.

13 C Kinetic Isotope Effects as a Quantitative Probe To Distinguish between Enol and Enamine Mechanisms in Aminocatalysis.

A combination of experimental 13 C kinetic isotope effects (KIEs) and high-level density functional theory (DFT) calculations is used to distinguish between "enamine" and "enol" mechanisms in the Michael addition of acetone to trans-β-nitrostyrene catalyzed by Jacobsen's primary amine thiourea catalyst. In light of the recent findings that the widely used 18 O-incorporation probe for these mechanisms is flawed, the results described in this communication demonstrate an alternative probe to distinguish between these pathways. A key advantage of this probe is that quantitative mechanistic information is obtained without modifying experimental conditions. This approach is expected to find application in resolving mechanistic debates, while providing valuable information about the key transition state of organocatalyzed reactions involving the α-functionalization of carbonyls.

Heterogeneous Jacobsen's catalyst on alkoxyl‐modified zirconium poly (styrene‐phenylvinylphosphonate)‐phosphate (ZPS‐PVPA) for asymmetric epoxidation

Chiral Jacobsen's catalysts grafted onto alkoxyl‐modified ZPS‐PVPA exhibit excellent activities (conv%, up to 96; sele%, up to 96; ee%, up to &gt;99) in the asymmetric epoxidations of unfunctionalized olefins. The superior stabilities and the comfortable dispositions in large‐scale reactions contribute to the potential applications in industry.

Retracted: Chiral Jacobsen's catalyst immobilized on zinc poly(styrene‐phenylvinylphosphonate)‐phosphate functionalized by diamine as highly efficient and reusable catalyst for alkene epoxidation

Chiral Jacobsen's catalyst anchored on zinc poly(styrene‐phenylvinylphosphonate)‐phosphate (ZnPS‐PVPA) functionalized by diamines shows superior catalytic activities (conversion up to 99%; enantiomeric excess up to 99%) in the enantioselective epoxidations of unfunctional olefins with m‐chloroperoxybenzoic acid and NaIO4 as oxidants. The whole chiral salen Mn(III) catalyst, including the ZnPS‐PVPA support and the linker as well as chiral salen Mn ligand together contribute to the chirality of products. The heterogeneous catalyst has the potential for use in industry owing to superior stability (recycling nine times) and activity in large‐scale reactions (such as 200 times).

Apigenin-7-O-glucoside oxidation catalyzed by P450-bioinspired systems

Apigenin-7-O-glucoside (A7G) is the main flavonoid of Bidens gardneri Bak., a Brazilian plant with wide application in folk medicine. Despite the popular use of this plant, its biological effects are not completely known. This work tested the 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin iron(III) and manganese(III) chloride (Fe(TFPP)Cl and Mn(TFPP)Cl), and Jacobsen's catalyst as P450-bioinspired catalysts for A7G oxidation by different oxidants (PhIO, H2O2, m-CPBA, and t-BuOOH). Up to nine different products were detected by HPLC analysis; Reactions with metalloporphyrin/PhIO systems afforded high catalytic conversions (58–89%). In spite of providing smaller product yields, the metalloporphyrin/H2O2 systems led to superior product distribution. Fe(TFPP)Cl yielded the highest A7G conversion rates (79–93%) with the four different oxidants tested herein. In the presence of PhIO, the oxidative profile of the manganese catalysts was very close to the oxidative profile of Fe(TFPP)Cl. However, in medium containing peroxide, the reactivity of the manganese catalysts was lower as compared to the reactivity of Fe(TFPP)Cl. Reactions with Fe(TFPP)Cl/oxidant systems were analyzed by UPLC-MS; up to thirteen compounds were detected. A7G oxidation catalyzed by Fe(TFPP)Cl yielded seven compounds. Three other compounds had m/z profile compatible with the profile of the A7G metabolites. The A7G oxidation assays performed in the presence of P450-bioinspired catalysts demonstrated their great catalytic potential toward A7G. The present results may be useful to many areas of knowledge and to the research and development of numerous chemical and phamarcological processes, especially in terms of drug design, biological assays, and applications in medicinal chemistry.

RETRACTED: Enantioselective epoxidation of unfunctionalized olefins by Jacobsen's catalyst immobilized on amino-modified ZnPS-PVPA

This article has been retracted at the request of the Chinese Journal of Catalysis . This article contains a substantial amount of text and data that had previously appeared in other published articles, including Inorganic Chemistry Communications , 65(2016)4-8 and RSC Advances , 6(2016)19509. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. As such this article represents misconduct in article publication. In accordance with policies and procedures governing academic publication we concluded that the above-mentioned article published in Chinese Journal of Catalysis be retracted. We apologize to readers of the journal that this was not detected before publication.

In Vitro Metabolism Evaluation of the Ergot Alkaloid Dihydroergotamine: Application of Microsomal and Biomimetic Oxidative Model.

Dihydroergotamine is a semisynthetic natural product derived from ergotamine, an ergot alkaloid. It is used to treat migraines, a neurological disease characterized by recurrent moderate to severe headaches. In this work, the in vitro metabolism of dihydroergotamine was evaluated in a biomimetic phase I reaction, aiming to verify all possible formed metabolites. Dihydroergotamine was submitted to an in vitro metabolism assay using rat liver microsomes, and the metabolites were analyzed by HPLC-MS/MS. The biomimetic reactions were performed with Jacobsen catalyst for scaling up production of oxidized metabolites. Two hydroxylated metabolites were isolated and characterized by MS/MS and 1H NMR analysis.

Mechanistic Investigation on Oxygen Transfer with the Manganese‐Salen Complex

AbstractThe best‐known application of salen complexes is the use of a chiral ligand loaded with manganese to form the Jacobsen complex. This organometallic catalyst is used in the epoxidation of unfunctionalized olefins and can achieve very high selectivities. Although this application was proposed many years ago, the mechanism of oxygen transfer remains a question until now. In this paper, the epoxidation mechanism is investigated by an ab initio kinetic modeling study. First of all a proper DFT functional is selected that yields the correct ordering of the various spin states. Our results show that the epoxidation proceeds via a radical intermediate. If we start from the radical intermediate, these results can explain the experiments with radical probes. The subtle influences in the transition state using the full Jacobsen catalyst explain the product distribution observed experimentally.

The enantioselectivity of the manganese-salen complex in the epoxidation of unfunctionalized olefins and the influence of grafting

Jacobsen’s complexes are famous for their usability for enantioselective epoxidations. However, the applicability of this catalytic system has been severely limited by several practical problems such as deactivation and separation after reaction. Grafting of Jacobsen-type complexes on solid supports is an attractive way to overcome these problems but led to a decrease in selectivity. A combined theoretical and experimental approach is presented to unravel the factors governing enantioselectivity. The importance of different substituents was determined by analyzing the transition state for the oxygen transfer using the full system as a model. An analysis of the asymmetric complex has shown an inherent tendency for a decreased selectivity due to the lack of specific bulky groups. Experimentally an immobilized Jacobsen catalyst on a metal organic framework (MIL-101) was synthesized which confirms the computational tendencies but the decrease in selectivity is limited, indicating that the MIL-101(Cr) is a suitable carrier for this complex.

Electrochemical Cyclization of Brominated Allyl Ethers with the Aid of a Chiral Catalyst

Control over the stereochemistry of a desired product in chemical synthesis is an ongoing problem. Specifically, the selectivity of chiral molecules has been the most challenging problem in organic synthesis. Often, to overcome this problem, chiral catalysts are employed to induce preference for one chiral product over another. One catalyst, known as the Jacobsen catalyst, has been utilized for the enantioselective oxidative conversion of alkenes to epoxides in the presence of a large amount of an oxidizer.1 In the field of electrochemistry, Duñach and co-workers utilized nickel(II) and cobalt(II) complexes with a Jacobsen ligand (a chiral, substituted salen) in constant-current experiments for the electrochemical reductive cyclization of brominated allyl ethers at room temperature, for which they achieved an enantiomeric excess as high as 16%.2 In the present work, we have explored the use of the same cobalt(II) catalyst as Duñach and co-workers, but conducted the experiments under controlled-potential conditions in order to increase the enantiomeric excess. We expanded the study to more substrates to observe how ther products change as a function of structure. A generalized reaction is shown in Scheme 1 for the one-electron reductive cyclization of brominated allyl ethers to form the chiral product of interest. Experiments have been conducted to optimize reaction conditions such as temperature, concentration, and solvent. Finally, we changed the stereochemistry of the catalyst from the R species to the S species for the purpose of controlling the identity of our products. 1. Jacobsen, in: I. Ojima (Ed.), Catalytic Asymmetric Synthesis, VCH, New York, 1993 (Chapter 4.2).2. Duñach, E.; Esteves, A. P.; Medeiros, M. J.; Pletcher, D.; Olivero, S. J. Electroanal. Chem. 2004, 566, 39–45. Figure 1

Chiral MnIII(Salen) supported on tunable phenoxyl group modified zirconium poly (styrene-phenylvinylphosphonate)-phosphate as an efficient catalyst for epoxidation of unfunctionalized olefins

We have developed a series of chiral MnIII(Salen) (chiral Jacobsen's catalyst) catalysts that were axially supported onto zirconium poly(styrene-phenylvinylphosphonate)-phosphate through tunable phenoxyl linkers of varying steric hindrance, and evaluated their performance as catalysts (Cat1–Cat3) for the epoxidation of unfunctionalized olefins using m-chloroperbenzoic acid as an oxidant. The corresponding non-supported analogues (Cat4–Cat6) were also prepared and tested under similar conditions. The results demonstrated that the incorporation of substituents at the ortho-positions of the tunable phenoxyl linkers had a critical effect on the catalytic activity. Furthermore, the enantioselectivity increased as the steric hindrance imposed by the linker increased, although this also led to a decrease in the conversions under the same reaction conditions, especially for heterogeneous epoxidation. The heterogeneous system also displayed high ee values and conversions in the absence of the axial additive N-methylmorpholine N-oxide, which is commonly required to improve the catalytic activity of epoxidation reactions, especially for the epoxidation of α-methylstyrene. The reusability of the catalyst was also evaluated over 11 catalytic cycles, with no significant reduction observed in the catalytic activity or enantioselectivity after five runs.