Presence Of Transition Metal Complexes Research Articles

MIL-125-based nanocarrier decorated with Palladium complex for targeted drug delivery

The aim of this work was to provide a novel approach to designing and synthesizing a nanocomposite with significant biocompatibility, biodegradability, and stability in biological microenvironments. Hence, the porous ultra-low-density materials, metal–organic frameworks (MOFs), have been considered and the MIL-125(Ti) has been chosen due to its distinctive characteristics such as great biocompatibility and good biodegradability immobilized on the surface of the reduced graphene oxide (rGO). Based on the results, the presence of transition metal complexes next to the drug not only can reinforce the stability of the drug on the structure by preparing π–π interaction between ligands and the drug but also can enhance the efficiency of the drug by preventing the spontaneous release. The effect of utilizing transition metal complex beside drug (Doxorubicin (DOX)) on the drug loading, drug release, and antibacterial activity of prepared nanocomposites on the P. aeruginosa and S. aureus as a model bacterium has been investigated and the results revealed that this theory leads to increasing about 200% in antibacterial activity. In addition, uptake, the release of the drug, and relative cell viabilities (in vitro and in vivo) of prepared nanomaterials and biomaterials have been discussed. Based on collected data, the median size of prepared nanocomposites was 156.2 nm, and their biological stability in PBS and DMEM + 10% FBS was screened and revealed that after 2.880 min, the nanocomposite’s size reached 242.3 and 516 nm respectively. The MTT results demonstrated that immobilizing PdL beside DOX leads to an increase of more than 15% in the cell viability. It is noticeable that the AST:ALT result of prepared nanocomposite was under 1.5.

Recent Advances in Transition-Metal-Catalyzed C–H Functionalization Reactions Involving Aza/Oxabicyclic Alkenes

AbstractBicyclic alkenes, including oxa- and azabicyclic alkenes, readily undergo activation with facial selectivity in the presence of transition-metal complexes. This is due to the intrinsic angle strain on the carbon–carbon double bonds in such unsymmetrical bicyclic systems. During the past decades considerable progress has been made in the area of ring opening of bicyclic strained rings by employing the concept of C–H activation. This short review comprehensively compiles the various C–H bond activation assisted reactions of oxa- and azabicyclic alkenes, viz., ring-opening reactions, hydroarylation, and annulation reactions.1 Introduction2 Reactions of Heterobicyclic Ring Systems2.1 Ring-Opening Reactions of Oxa- and Azabenzonorbornadienes2.1.1 Reactions Using 7-Oxabenzonorbornadienes2.1.2 Reactions Using 7-Azabenzonorbornadienes2.2 Hydroarylation Reactions2.3 Annulation Reactions2.4 Other Reactions3 Conclusion

C-Methylation of Organic Substrates: A Comprehensive Overview. Part II—Methyl Metals as Methylating Agents

C-Methylation of organic substrates was achieved with a number of methyl metals, including trimethylaluminum (Me3Al), trimethylgallium (Me3Ga), trimethylindium (Me3In), dimethylzinc (Me2Zn), methyl zinc halide (MeZnX), methylboranes (MeBRR’), methylboronic acid (MeB(OH)2), methylboronates (MeB(OR)2), methylcopper (MeCu), methyllithium cuprate (Me2CuLi), methylmagnesium halides (MeMgX), tetramethyltin (Me4Sn), methyl lithium, and lead tetraacetate. Most of the related reactions required the presence of transition metal complexes as catalysts and phosphine ligands. Overall, the yields of the methylated products actually depended on the types of used catalyst and ligand. In some instances, additives were needed as specific promoters, such as p-benzoquinone in the methylation through coupling with methyl boron agents. Best of all, methylation of substrates with some of these methylating agents occurred with some features. For example, asymmetric reactions of carbonyl compounds could be accomplished using dimethyzinc along with a specific ligand, leading to moderate to excellent yields of the major enantiomer with high enantiomeric excess. Ortho-methylation regioselectively occurred on aromatic substrates when they bear moieties such as heteroarenes (pyridine), amide, azomethine, oxazoline, N-nitrosoamine, oxime, coined ‘ortho-directing groups’.

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

Progress in Difluoroalkylation of Organic Substrates by Visible Light Photoredox Catalysis.

The selective incorporation of fluorinated motifs, in particular CF2FG (FG=a functional group) and CF2H groups, into organic compounds has attrracted increasing attention since organofluorine molecules are of the utmost importance in the areas of nuclear imaging, pharmaceutical, agrochemical, and material sciences. A variety of synthetic approaches has been employed in late‐stage difluoroalkylation reactions. Visible light photoredox catalysis for the production of CF2FG and CF2H radicals has provided a more sustainable alternative to other conventional radical‐triggered reactions from the viewpoint of safety, cost, availability, and “green” chemistry. A wide range of difluoroalkylating reagents has been successfully implemented in these organic transformations in the presence of transition metal complexes or organic photocatalysts. In most cases, upon excitation via visible light irradiation with fluorescent light bulbs or blue light‐emitting diode (LED) lamps, these photocatalysts can act as both reductive and oxidative quenchers, thus enabling the application of electron‐donor or electron‐acceptor difluoroalkylating reagents for the generation of CF2FG and CF2H radicals. Subsequent radical addition to substrates and additional organic transformations afford the corresponding difluoroalkylated derivatives. The present review describes the distinct strategies for the transition metal‐ and organic‐photocatalyzed difluoroalkylation of a broad range of organic substrates by visible light irradiation reported in the literature since 2014.

Asymmetric Oxidation and Carbene Transfer Reactions Catalyzed By Metalloporphyrins in Water

The development of environmentally benign reactions is an important goal in synthetic organic chemistry and chemical engineering. However, catalytic enantioselective reactions using transition-metal complexes in protic or aqueous solvents are within limited ranges. The current applications of asymmetric catalysis using metalloporphyrins will be reported (1). Distinct methodologies have been developed for carbene transfer and oxidation reactions such as the use of water-soluble catalysts (2). Comparison between hydrophobic and hydrophilic solvents will be discussed from an asymmetric point of view. Catalytic enantioselective oxidations using transition-metal complexes are limited when the oxidant is hydrogen peroxide. The two main difficulties of using hydrogen peroxide in the presence of transition metal complexes are the homolytic cleavage generating OH radicals and the catalase reaction with formation of dioxygen. Asymmetric sulfoxidation, epoxidation of alkenes and hydroxylation catalyzed by iron and manganese porphyrins will be described (3). Thus the asymmetric epoxidation of styrene derivatives by H2O2 (or UHP) to give optically active epoxides (ee up to 81%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 78%) were carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts. (1) Recent Advances in Catalysis by Water-Soluble Metalloporphyrins G. Simonneaux, P. Le Maux, S. Chevance and H. Srour. Handbook of Porphyrin Science, 2012, Vol. 21, 377-410 (2) Enantioselective Manganese-Porphyrin-Catalyzed Epoxidation and C-H hydroxylation with Hydrogen Peroxide in Water/Methanol Solutions H. Srour, P. Le Maux and G. Simonneaux. Inorg. Chem. 2012, 51, 5850-5856. (3) Metal-catalyzed asymmetric sulfoxidation, epoxidation and hydroxylation by hydrogen peroxide Hassan Srour, Paul Le Maux, Soizic Chevance, Gérard Simonneaux. Coord. Chem. Rev., 257 (2013) 3030– 3050

ChemInform Abstract: Metal‐Catalyzed Asymmetric Sulfoxidation, Epoxidation and Hydroxylation by Hydrogen Peroxide

AbstractReview: 214 refs.

ChemInform Abstract: Metal‐Free Aerobic Oxidations Mediated by N‐Hydroxyphthalimide. A Concise Review

AbstractReview: 73 refs.

A Greener Approach for Synthesis of Functionalized Polyolefins by Introducing Reactive Functionality into Ethylene Copolymers

Recent successful examples for synthesis of new polyolefins containing (polar) functionalities by adopting the approaches by controlled incorporation of reactive functionalities (and the subsequent introduction of polar functionalities under mild conditions) by coordination polymerization in the presence of transition metal complex catalysts have been described. Related methods (such as direct copolymerization of olefin with polar monomer using living radical or coordination insertion methods) have also been demonstrated for comparison. Our recent efforts for precise synthesis of polyolefins containing polar functionalities by efficient incorporation of reactive functionality by copolymerization of ethylene with nonconjugateddiene (1,7-octadiene, vinylcyclohexene etc.) or divinyl-biphenyl using nonbridged half-titanocene [ex. Cp’TiCl2(O-2,6-iPr2C6H3), Cp’ = C5Me5, tBuC5H4 etc.] catalysts have been introduced.

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

Since the beginning of the century, N-hydroxyphthalimide and related compounds have been revealed to be efficient organocatalysts for free-radical processes and have found ample application in promoting the aerobic oxidation of a wide range of organic substrates. When combined with different co-catalysts, they are activated to the corresponding N-oxyl radical species and become able to promote radical chains, involving molecular oxygen, directly or indirectly. Most of the examples reported in the literature describe the use of these N-hydroxy derivatives in the presence of transition-metal complexes. However, eco-friendly standards, including the demand for highly selective transformations, impose the development of metal-free processes, especially for large-scale productions, as in the case of the oxygenation of hydrocarbons. For this reason, many efforts have been devoted in the past decade to the design of new protocols for the activation of N-hydroxy imides in the presence of nonmetal initiators. Herein we provide a concise overview of the most significant and successful examples in this field, with the final aim to furnish a useful instrument for all scientists actively involved in the O2-mediated selective oxidation of organic compounds and looking for environmentally safe alternatives to metal catalysis.

Binuclear complexes with the “Chinese Lantern” geometry as intermediates in the liquid-phase oxidation of dibenzyl ether with atmospheric oxygen in the presence of copper(II) carboxylates

Reactions of copper(II) carboxylates with dibenzyl ether (DBE) gave binuclear complexes of the formula Cu2(μ-OOCR)4(DBE)2 (R = But, Ph, and CF3). The complexes were characterized by X-ray diffraction. The axial positions in the lantern-type dimer are occupied by the coordinated DBE molecules. The complexes seem to be analogs of intermediate catalysts for the oxidation of DBE with atmospheric oxygen in the presence of transition metal complexes. When stored in air, the complex Cu2(μ-OOCPh)4(DBE)2 underwent oxidation into Cu2(μ-OOCPh)4(HOOCPh)2, which was characterized by X-ray diffraction. The geometry of its framework is similar; the structure is stabilized by intramolecular H bonds between the axially oriented benzoic acid molecules and the adjacent bridging benzoate anions.

ChemInform Abstract: Synthesis of Cyclohepta-1,3,5-trienes by Reaction of Aromatic Hydrocarbons with Diazo Compounds in the Presence of Transition Metal Complexes.

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Chemically induced dynamic nuclear polarization and the mechanism of the reaction of Et3Al with CCl4 in the presence of transition metal complexes

Integral effects of chemically induced 1H and 13C nuclear polarization are reported for the reaction of Et3Al with CCl4 catalyzed by Pd(acac)2, Cu(acac)2, and Cp2TiCl2; for the reaction of (n-C8H17)3Al with CCl4 in the absence of a catalyst and in the presence of Ni(acac)2; and for the reaction of the cyclic organoaluminum compound 1-ethyl-3-butylaluminacyclopentane with CCl4 in the presence of Pd(acac)2. A scheme of the catalytic cycle of this reaction predicting the formation of both radical and nonradical products is derived from the observed chemically induced dynamic nuclear polarization (CIDNP) effects and from data on the products of the reaction between Et3Al and CCl4 in the presence of Pd(acac)2. According to the results of qualitative analysis of the CIDNP effects, the reactions of the trialkylalanes and the cyclic organoaluminum compound with CCl4 in the presence of various metal complexes proceeded via similar mechanisms.

Hydroamination of conjugated dienes catalyzed by transition metal complexes

The review summarizes published data on the hydroamination of 1,3-dienes with various primary and secondary amines, ammonia, and ammonium salts of mineral acids in the presence of transition metal complexes under homogeneous conditions. The effects of the nature of metal, ligand, initial diene, and amine and reaction conditions on the selectivity of hydroamination are considered, and possible reaction mechanisms are discussed.

Alkenylation of aromatic compounds

The review summarizes new data on the introduction of alkenyl (vinyl) groups into aromatic and heteroaromatic structures via reactions with alkenes and alkynes. The main attention is given to the characterization and estimation of synthetic potential of the alkenylation of aromatic compounds with acetylene derivatives in the presence of transition metal complexes, as well as by the action of electrophiles, Lewis acids, and Bronsted superacids.

One‐Pot Synthesis of Substituted Quinolines by Iridium‐Catalyzed Three‐Component Coupling Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

One-pot Synthesis of Substituted Quinolines by Iridium-catalyzed Three-component Coupling Reaction

Abstract A convenient and efficient synthesis of substituted quinolines in a simple one-pot reaction of an arylamine 1, an aromatic aldehyde or aliphatic aldehyde 2 and an aliphatic aldehyde 3 in the presence of transition metal complexes or Lewis acids was developed. Among them, the iridium catalyst [Ir(cod)Cl]2 catalyzed the reaction most efficiently.

Stereoselective synthesis of (E)‐α‐aryltellurenylvinylstannanes and their application in the synthesis of stereodefined trisubstituted alkenes

Abstract(E)‐α‐Aryltellurenylvinylstannanes have been synthesized stereoselectively via the hydrozirconation of alkynylstannanes, followed by the reactions with aryltellurenyl iodides. (E)‐α‐Aryltellurenylvinylstannanes can undergo sequential cross coupling reactions with both electrophiles and nucleophiles in the presence of transition metal complexes to form two carbon‐carbon bonds in the same olefinic carbon leading to trisubstituted alkenes stereoselectively.

Metal complexes as phase transfer catalysts in the synthesis of O-acetylmandelonitrile

The asymmetric synthesis of O-acetylated mandelonitrile derivative was accomplished from PhCHO, KCN, and Ac2O in a toluene--water system in the presence of transition metal complexes of Schiff"s bases as phase transfer catalysts.

(E)‐α‐Bromovinylselenides as Convenient Precursors for Stereoselective Synthesis of Trisubstituted Alkenes

AbstractBased on the different reactivity of selanyl and bromo groups, (E)‐α‐bromovinylselenides can undergo sequential cross coupling reactions with nucleophiles in the presence of transition metal complexes to form two carbon‐carbon bonds in the same olefinic carbon leading to trisubstituted alkenes stereoselectively in good yields.