Selective Carbonylation Research Articles

Proteomic identification of carbonylated proteins in 1,3-dinitrobenzene neurotoxicity

This study demonstrated that 1,3-dinitrobenzene-induced (1,3-DNB) oxidative stress led to the oxidative carbonlyation of specific protein targets in DI TNC1 cells. 1,3-DNB-induced mitochondrial dysfunction, as indicated by loss of tetramethyl rhodamine methyl ester (TMRM) fluorescence, was initially observed at 5h and coincided with peak reactive oxygen species (ROS) production. ROS production was inhibited in cells pre-treated with the mitochondrial permeability transition (MPT) inhibitor, bonkrekic acid (BkA). Pre-incubation with the antioxidant deferoxamine inhibited loss of TMRM fluorescence until 24h after initial exposure to 1,3-DNB. Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and subsequent Oxyblot analysis were used to determine if 1,3-DNB exposure led to the formation of protein carbonyls. Exposing DI TNC1 cells to 1,3-DNB led to marked protein carbonylation 45min following initial exposure. Pre-treatment with deferoxamine or Trolox reduced the intensity of protein carbonylation in DI TNC1 cells exposed to 1mM 1,3-DNB. Tandem MS/MS performed on protein samples isolated from 1,3-DNB-treated cells revealed that specific proteins within the mitochondria, endoplasmic reticulum (ER), and cytosol are targets of protein carbonylation. The results presented in this study are the first to suggest that the molecular mechanism of 1,3-DNB neurotoxicity may occur through selective carbonylation of protein targets found within specific intracellular compartments of susceptible cells.

Triphenylphosphane-Modified Cobalt Catalysts for the Selective Carbonylation of Ethyl Diazoacetate

The triphenylphosphane-substituted carbonyl cobalt complexes Co2(CO)7(PPh3), Co2(CO)6(CHCO2Et)(PPh3), and [Co(CO)3(PPh3)2][Co(CO)4] were found to be more effective precatalysts in the carbonylation of ethyl diazoacetate under atmospheric pressure of carbon monoxide at 10 °C in dichloromethane solution than the parent Co2(CO)8 and Co2(CO)7(CHCO2Et) complexes. The highly reactive (ethoxycarbonyl)ketene is the primary product of the catalytic carbonylation, which dimerizes in the absence of a proper scavenger. In the presence of ethanol as the trapping reagent diethyl malonate is the final product of the carbonylation reaction. The formation of (ethoxycarbonyl)ketene using the catalyst precursor Co2(CO)7(PPh3) occurs in a catalytic cycle, where Co2(CO)6(PPh3) and Co2(CO)6(CHCO2Et)(PPh3) are the repeating species. The 16e species Co2(CO)6(PPh3) is involved in the deazotization of ethyl diazoacetate, and Co2(CO)6(CHCO2Et)(PPh3) leads to the (ethoxycarbonyl)ketene formation. In the absence of carbon monoxide or at low CO concentration the reaction of Co2(CO)6(CHCO2Et)(PPh3) with ethyl diazoacetate is the source of Co2(CO)5(CHCO2Et)2(PPh3), which is not an active catalyst for the carbonylation of ethyl diazoacetate. Using [Co(CO)3(PPh3)2][Co(CO)4] as the catalyst precursor, the intermediary formation of [Co(CO)3(PPh3)2][Co(CO)3(O═C═CHCO2Et)] through radical pairs is assumed. Substituting PPh3 in Co2(CO)7(PPh3), Co2(CO)6(CHCO2Et)(PPh3), and [Co(CO)3(PPh3)2][Co(CO)4] by polymer-bound PPh3 results in active and reusable catalysts for the selective carbonylation of ethyl diazoacetate in dichloromethane solution at 40 °C and 11 bar of pressure with up to 5.1 mol of product/((mol of catalyst) h) turnover frequency.

Enzyme-like Specificity in Zeolites: A Unique Site Position in Mordenite for Selective Carbonylation of Methanol and Dimethyl Ether with CO

The mechanism of methanol carbonylation at different positions of zeolite MOR is investigated by quantum-chemical methods in order to discover which are the active sites that can selectively catalyze the desired reaction. It is shown that when methanol carbonylation competes with hydrocarbon formation, the first reaction occurs preferentially within 8MR channels. However, the unique selectivity for the carbonylation of methanol and dimethyl ether in mordenite is not only due to the size of the 8MR channel: neither process occurs equally at the two T3-O31 and T3-O33 positions. We show that only the T3-O33 positions are selective and that this selectivity is due to the unusual orientation of the methoxy group in relation to the 8MR channel (parallel to the cylinder axis). Only in this situation does the transition state for the attack of CO fit perfectly in the 8MR channel, while the reaction with methanol or DME is sterically impeded. This result explains why T3-O31, while also located in the 8MR channel of mordenite, is not as selective as the T3-O33 position and why ferrierite, although it contains 8MR channels, is less selective than mordenite. The competing effect of water is explained at the molecular level, and the molecular microkinetic reaction model has been established.

Highly Regioselective Rhodium‐Catalyzed Hydroformylation of Unsaturated Esters: The First Practical Method for Quaternary Selective Carbonylation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Highly Regioselective Rhodium‐Catalysed Hydroformylation of Unsaturated Esters: The First Practical Method for Quaternary Selective Carbonylation

Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50 degrees C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give beta-amino acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual beta-amino acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent alpha-selectivity and good chemoselectivity for the first time.

Identification of Specific Protein Carbonylation Sites in Model Oxidations of Human Serum Albumin

Human serum albumin (HSA) was subjected to oxidative stress and the locations of the resulting protein carbonyls were determined using mass spectrometry in conjunction with a hydrazide labeling scheme. To model oxidative stress, HSA samples were subjected to metal-catalyzed oxidation (MCO) conditions or treated with hypochlorous acid (HOCl). Oxidation led to the conversion of lysine residues to 2-aminoadipic semi-aldehyde residues, which were subsequently labeled with biotin hydrazide. Analysis of the tryptic peptides from the samples indicates that the oxidations are highly selective. Under MCO conditions, only two of the 59 lysine residues appeared to be modified (Lys-97 and Lys-186). With HOCl, five different lysine modification sites were identified (Lys-130, Lys-257, Lys-438, Lys-499, and Lys-598). These results strongly suggest that the preferred site of modification is dependent on the nature of the oxidant and that the process relies on specific structural motifs in the protein to direct the oxidation. The high selectivity seen here provides insights into the factors that in vivo drive the selective carbonylation of specific proteins in systems under oxidative stress.

High Efficient Electrochemical Carbonylation of Methanol to Dimethyl Carbonate by Br2 ∕ Br − Mediator System over Pd ∕ C Anode

Electrochemical carbonylation of methanol to dimethyl carbonate (DMC) was studied over anode with XBr electrolyte (, , ). The formation rate, the current efficiency, and the selectivity of DMC with LiBr electrolyte were considerably higher than that with other supporting electrolyte, , , LiCl, , LiI, and . A turnover number of Pd electrocatalyst for DMC formation was over . Current efficiency of 80% and selectivity based on and CO of 95% were observed. Data of kinetic experiments and stoichiometric experiments strongly suggested that electrochemically produced works as an oxidant for the oxidative carbonylation of methanol to DMC catalyzed by on carbon. A very active and selective carbonylation of methanol to DMC was performed by indirect electrolysis with redox mediator.

Selective Carbonylation of Dimethyl Ether to Methyl Acetate Catalyzed by Acidic Zeolites

Selective Carbonylation of Dimethyl Ether to Methyl Acetate Catalyzed by Acidic Zeolites

Selective Carbonylation of Dimethyl Ether to Methyl Acetate Catalyzed by Acidic Zeolites

A simpler way: Acidic zeolites catalyze dimethyl ether carbonylation to methyl acetate at low temperatures with high selectivity and catalyst stability. This approach provides a halide-free heterogeneous catalytic route to acetic acid and methyl acetate.

Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate: A Highly Active, Selective, and Versatile Catalyst for Epoxide Carbonylation.

The development of a highly active and selective porphyrin-based epoxide carbonylation catalyst, [(OEP)Cr(THF)2][Co(CO)4] (1; OEP = octaethylporphyrinato; THF = tetrahydrofuran), is detailed. Complex 1 is a separated ion pair composed of a tetracarbonylcobaltate anion and an octahedral chromium porphyrin complex axially ligated by two THF ligands. Regarding the carbonylation of epoxides to β-lactones, catalyst 1 exhibits excellent turnover numbers (up to 10 000) and turnover frequencies (up to 1670 h-1), with regioselective carbonyl insertion occurring between the oxygen and the sterically less hindered carbon of the epoxide substrate. Complex 1 is highly tolerant of nonprotic functional groups, carbonylating an array of aliphatic and cycloaliphatic epoxides, as well as epoxides with pendant ethers, esters, and amides. With careful control of reaction conditions in the carbonylation of glycidyl esters, the exclusive production of either the β- or γ-lactone isomer was achieved. Through analysis of reaction...

Preparation of triphenylphosphane substituted ethoxycarbonylcarbene-bridged dicobalt carbonyl complexes and their application as catalyst precursors in the carbonylation of ethyl diazoacetate to diethyl malonate

The triphenylphosphane substituted derivatives Co 2(CO) 6(CHCO 2Et)(PPh 3), [μ 2-{ethoxycarbonyl(methylene)}-μ 2-(carbonyl)-(tricarbonyl-cobalt)-(triphenylphosphane-dicarbonyl-cobalt) (Co Co)] ( 3) and Co 2(CO) 5(CHCO 2Et)(PPh 3) 2, [μ 2-{ethoxycarbonyl-(methylene)}-μ 2-(carbonyl)-bis(triphenylphosphane-dicarbonyl-cobalt) (Co–Co)] ( 4) were prepared from the known Co 2(CO) 7(CHCO 2Et) ( 1) and Co 2(CO) 6(CHCO 2Et) 2 ( 2) complexes with triphenylphosphane. The new complexes 3 and 4 as well as Co 2(CO) 7(PPh 3), Co 2(CO) 6(PPh 3) 2, and Co 2(CO) 6 (dppm) (dppm = Ph 2PCH 2PPh 2) were found to be suitable catalyst precursors in the selective carbonylation of ethyl diazoacetate to diethyl malonate in the presence of ethanol.

Rhodium-catalyzed C-H–CO–olefin coupling reactions — A chelation-assisted direct carbonylation at the ortho C—H bond in the benzene ring of 2-arylpyridines

The reaction of 2-arylpyridines with ethylene and carbon monoxide in the presence of a catalytic amount of Rh4(CO)12 results in selective carbonylation at the ortho C—H bond. The reaction is heavily dependent on the solvents used, with DMA (N,N-dimethylacetamide) being the solvent of choice. Steric factors are also important determinants of the efficiency of the reaction.Key words: C—H bond activation, carbonylation, chelation, rhodium, carbon monoxide.

Palladium‐Catalyzed Selective Carbonylation of (E)‐1,2‐Diidoalkenes

A mild and selective palladium‐catalyzed carbonylation of (E)‐1,2‐diiodoalkenes protocol for the synthesis of (E)‐3‐iodoacrylate esters and maleic diesters has been developed. In the presence of PdCI2, CuCl2, and CO, (E)‐3‐iodoacrylate esters and maleic diesters were obtained selectively in moderate yields. Noteworthysis that a clean inversion of configuration takes place in the palladium‐catalyzed dicarbonylation of (E)‐1,2‐diiodoalkenes procedure.

Selective carbonylation of benzene to benzaldehyde using O2 as the oxidant in the presence of cobalt complex

Abstract An efficient strategy on facial, environmentally friendly, economic, selective carbonylation of benzene to give benzaldehyde using O2 as the oxidant was firstly developed. Co(OAc)2/CCl3COOH with the addition of additives such as pyridine was found to be an effective catalyst system for direct catalytic carbonylation of benzene to benzaldehyde with relatively high yield (37.3%) and selectivity(80%) under mild conditions. The influence of various reaction conditions on reaction performance was shown. A possible reaction mechanism was proposed.

Selective hydroalkoxycarbonylation of enamides to N-acyl amino acid esters: synthetic applications and theoretical studies

N-acyl amino acid esters are easily accessible from enamides by cobalt-catalyzed hydroalkoxycarbonylation in moderate to excellent yield. An important reaction parameter for selective carbonylation is the use of low hydrogen partial pressure, which prevents hydrogenation as a side reaction. The reported method is applicable to various enamides and alcohols. A DFT calculation of the catalytic cycle explains the preferred pathway of this reaction.

Selective carbonylation of benzene to benzaldehyde

An efficient strategy on facial, selective carbonylation of benzene to give benzaldehyde was developed. Co(OAc)2/K2S2O8/CCl3COOH/pyridine was found to be a novel multi-catalytic system for direct carbonylation of benzene to benzaldehyde under mild conditions, in which the yield of benzaldehyde was up to 38.3% at the present stage.

Facile and Selective Carbonylation of Methane in Superacids

The carbonylation of CH4 with carbon monoxide in superacids HF/SbF5 or HSO3F/SbF5 leads to the exclusive and quantitative formation of the acylium ion ([CH3CO]+[SbF6]−) with the concomitant stoichiometric formation of SbF3.

Selective Carbonylation of Methanol to Dimethyl Carbonate by Gas–Liquid–Solid-Phase Boundary Electrolysis

Abstract Selective and efficient electrochemical carbonylation of MeOH to DMC was performed over PdCl2/VGCF (vapor grown carbon fiber) anode by utilizing the three-phase boundary electrolysis at 1 atm (CO) and 298 K.

First examples of the selective carbonylation of C 6[sbnd]C 10 linear alkanes to tertiary carbonyl-containing compounds

The carbonylation of C6–C10n-alkanes with CO in the presence of CBr4·2AlBr3 at –40 °C and 1 atm CO leads to the products of non-destructive carbonylation, i.e., the esters of tertiary carboxylic acids, R1C(Me)2COOR and R2(Et)C(Me)COOR, after the workup of reaction mixtures with ROH.

A new synthesis of cyclobutanones: highly selective carbonylation of titanacyclobutane complexes prepared by free radical alkylation.

A new synthesis of cyclobutanones: highly selective carbonylation of titanacyclobutane complexes prepared by free radical alkylation.