Presence Of CuX Research Articles

Divergent Copper-salt-controlled Reactions of Donor-Acceptor Cyclopropanes and N-Fluorobenzene Sulfonimide: Access to the 1,3-Haloamines and Aminoindanes.

We herein report a method for divergent copper salt controlled reactions of donor-acceptor cyclopropanes and N-fluorobenzene sulfonimide (NFSI). Specifically, in the presence of CuX2 (X=Cl, Br), the cyclopropanes underwent formal umpolung 1,3-aminohalogenation bifunctionalization via a free radical mediated ring-opening process to afford 1,3-aminochlorination and 1,3-aminobromination products in moderate to good yields. In addition, by using CuI as a catalyst, we synthesized various aminoindane derivatives via 1,3-aminoarylation cyclization of D-A cyclopropanes, the reactions involved a free radical mediated ring-opening and subsequent ring expansion via C-H bond activation.

Synthesis of 2,2′-Bis(silyl)azobenzenes by Oxidation of 2-(Silyl)anilines

A method was developed for the synthesis of 2,2′-bis(trimethylsilyl)- and 2,2′-bis(triethoxysilyl)-azobenzenes based on oxidation of 2-(silyl)anilines with trimethylamine and N-methylmorpholine oxides in the presence of CuX (X = Cl, Br).

Selective functionalization of P₄ by metal-mediated C-P bond formation.

A new and selective one-step synthesis was developed for the first activation stage of white phosphorus by organic radicals. The reactions of NaCp(R) with P4 in the presence of CuX or FeBr3 leads to the clean formation of organic substituted P4 butterfly compounds Cp(R)2P4 (Cp(R): Cp(BIG)=C5(4-nBuC6H4)5 (1 a), Cp'''=C5H2tBu3 (1 b), Cp*=C5Me5 (1 c) und Cp(4iPr)=C5HiPr4 (1 d)). The reaction proceeds via the activation of P4 by Cp(R) radicals mediated by transition metals. The newly formed organic derivatives of P4 have been comprehensively characterized by NMR spectroscopy and X-ray crystallography.

Synthesis, characterization, and tyrosinase biomimetic catalytic activity of copper(II) complexes with schiff base ligands derived from α-diketones with 2-methyl-3-amino-(3H)-quinazolin-4-one

Abstract A template condensation of α-diketones (biacetyl, benzile and 2,3-pentanedione) with 2-methyl-3-amino-(3 H )-quinazolin-4-one (AMQ) in the presence of CuX 2 (X = Cl − , Br − , NO 3 - or ClO 4 - ) resulted in the formation of tetradentate Schiff base copper(II) complexes of the type [CuLX]X and [CuL]X 2 . Structural characterization of the complex species was achieved by several physicochemical methods, namely elemental analysis, electronic spectra, IR, ESR, molar conductivity, thermal analysis (TAG & DTG), and magnetic moment measurements. The stereochemistry, the nature of the metal chelates, and the catalytic reactivity are markedly dependent upon the type of counter anions and the ligand substituent within the carbonyl moiety. A square planar monomeric structure is proposed for the perchlorate, nitrate, and bromide complexes, in which the counter anions are loosely bonded to copper(II) ion. For the chloride complexes, the molar conductivities and the spectral data indicated that they have square-pyramidal environments around copper(II) center. The reported copper(II) complexes exhibit promising tyrosinase catalytic activity towards the hydroxylation of phenol followed by the aerobic oxidation of the resulting catechol. A linear correlation almost exists between the catalytic reactivity and the Lewis-acidity of the central copper(II) ion created by the donating properties of the parent ligand. The steric considerations could be accounted to clarify the difference in the catalytic activity of these functional models.

Controlled hydrogenation of P(VDF-co-CTFE) to prepare P(VDF-co-TrFE-co-CTFE) in the presence of CuX (X = Cl, Br) complexes

An environmentally friendly and controllable P(VDF-co-CTFE) hydrogenation route involving the transition-metal complex mediated radical chain transfer reaction is successfully developed to synthesize P(VDF-co-CTFE-co-TrFE). The typical transition metal catalysts of ATRP reaction could be applied in this process.

CO2 electrochemical reduction via adsorbed halide anions

The electrochemical reduction of CO2 was studied utilizing halide ions as electrolytes, specifically, aqueous solutions of KCl, KBr, KI. Electrochemical experiments were carried out in a laboratory-made, divided H-type cell. The working electrode was a copper mesh, while the counter and reference electrodes were a Pt wire and an Ag/AgCl electrode, respectively. The results of our work suggest a reaction mechanism for the electrochemical reduction of CO2 where the presence of Cu-X as the catalytic layer facilitates the electron transfer from the electrode to CO2. Electron-transfer to CO2 may occur via the X−ad(Br−, Cl−, I−)-C bond, which is formed by the electron flow from the specifically adsorbed halide anion to the vacant orbital of CO2. The stronger the adsorption of the halide anion to the electrode, the more strongly CO2 is restrained, resulting in higher CO2 reduction current. Furthermore, it is suggested that specifically adsorbed halide anions could suppress the adsorption of protons; leading to a higher hydrogen overvoltage. These effects may synergistically mitigate the over potential necessary for CO2 reduction, and thus increase the rate of electrochemical CO2 reduction.

CO 2 attraction by specifically adsorbed anions and subsequent accelerated electrochemical reduction

The electrochemical reduction of CO 2 was studied on a copper mesh electrode in aqueous solutions containing 3 M solutions of KCl, KBr and KI as the electrolytes in a two and three phase configurations. Electrochemical experiments were carried out in a laboratory-made, divided H-type cell. The working electrode was a copper mesh, while the counter and reference electrodes were Pt wire and Ag/AgCl electrode, respectively. Results of our work suggest a reaction mechanism for the electrochemical reduction of CO 2 in the two phase configuration where the presence of Cu-X as the catalytic layer facilitates the electron transfer from the electrode to CO 2. Electron-transfer to CO 2 may occur via the X ad −(Br −, Cl −, I −)–C bond, which is formed by the electron flow from the specifically adsorbed halide anion to the vacant orbital of CO 2. The stronger the adsorption of the halide anion to the electrode, the more strongly CO 2 is restrained, resulting in higher CO 2 reduction current. Furthermore, it is suggested that specifically adsorbed halide anions could suppress the adsorption of protons, leading to a higher hydrogen overvoltage. These effects may synergistically mitigate the overpotential necessary for CO 2 reduction, and thus increase the rate of electrochemical CO 2 reduction.

Synthesis, characterization and crystal structures of dinuclear macrocyclic Schiff base copper(I) complexes bearing different bridges

Utilizing a new 20-membered macrocyclic Schiff base ligand with two coordination sites formed from the [2+2] condensation of 1,3-diaminopropane and benzene-1,3-dicarboxaldehyde in the presence of CuX (X = Cl −, Br −, I −) salts, air-stable dicopper(I) complexes were synthesized in acetonitrile, intramolecularly linked via two halide groups, and characterized by different physico-chemical techniques. The single crystal X-ray diffraction technique indicates these complexes consist of two N 2X 2 donor sets that have distorted tetrahedral coordination environments around the copper(I) ions. In these halogen-bridged binuclear Cu 2LX 2 systems the Cu⋯Cu separation can be controlled, as this distance is reduced on increasing the halide size and hence the X⋯X repulsion, with the rigidity of the macrocycle playing a significant role.

Regioselective copper-catalyzed chlorination and bromination of arenes with O2 as the oxidant

Electron-rich aromatic C-H bonds undergo regioselective chlorination and bromination in the presence of CuX(2), LiX (X = Cl, Br) and molecular oxygen. Preliminary mechanistic insights suggest that the bromination and chlorination reactions proceed by different pathways.

Electrophilic ipso-Cyclization of N-(p-Methoxyaryl)propiolamides Involving an Electrophile-Exchange Process

A novel electrophilic ipso-cyclization involving an electrophile-exchange process has been developed. In the presence of CuX (X = I, Br, SCN) and electrophilic fluoride reagents, a variety of N-(p-methoxyaryl)propiolamides and 4-methoxyphenyl 3-phenylpropiolate were cyclized to selectively afford the corresponding spiro[4.5]decenones in moderate to good yields. It is noteworthy that two azaquaternary tricyclic products were synthesized through a two-step pathway involving an electrophilic ipso-cyclization and then an intramolecular Heck reaction.

Synthesis of 1,4‐Disubstituted 1,2,3‐Triazoles via a Three‐Component Reaction in Water in the Presence of CuX (X: Cl, I).

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Synthesis of 1,4‐disubstituted 1,2,3‐triazoles via a three‐component reaction in water in the presence of cux (X = Cl, I)

Abstractmagnified imageThree‐component reaction of alkyl halides, sodium azide and alkynes in water in the presence of CuX (X = Cl, I) afforded 1,4‐disubstituted 1,2,3‐triazoles in high yields. These reactions do not require any special precautions or existence of a reducing agent. The bistriazoles formed during the reaction can efficiently enhance the catalytic activity of the Cu(I) salts.

Scope of the Copper Halide/Bipyridyl System Associated with Calixarene-Based Multihalides for the Synthesis of Well-Defined Polystyrene and Poly(meth)acrylate Stars

Novel multihalide compounds which were readily obtained by derivatization of 4-tert-butylcalix[4,6,8]arenes were used to initiate the atom transfer radical polymerization (ATRP) of styrene, tert-butyl acrylate (t-BuA), and methyl methacrylate (MMA), in the presence of CuX (X = Br or Cl) and 2,2‘-bipyridyl. Well-defined polystyrene (PS) stars constituted of precisely four, six, and eight arms could be synthesized with a narrow polydispersity in this way. For instance, octafunctional polystyrene stars exhibiting molar masses as high as 600 000 g mol-1 could be prepared. However, the polymerization had to be restricted to low conversion, typically below 15−20% to prevent stars from mutually coupling and avoid their contamination with species of higher functionality. Besides the concentration of polymeric radicals [P•], the factor that was found to play a significant role in the occurrence of star−star coupling is their overlapping concentration (C*): intermolecular coupling indeed appeared to be enhanced whe...

Stereoselective synthesis of enantiopure β, γ-disubstituted α-alkylideneγ-butyrolactones via A palladium(II) catalyzed cyclization

β, γ-disubstituted α-alkylidene-γ-butyrolactones with cis or trans relative configurations were synthesized in both optically active forms from readily available homochiral allylic 2-alkynoates by Pd(II) catalysis in the presence of CuX 2 and LiX.

Cu(I)-CATALYZED REACTION OF TERMINAL ALKYNES WITH PHENYL SELENOCYANATE IN THE PRESENCE OF TRIETHYLAMIME. SYNTHESIS OF ALKYNYL SELENIDES1

Abstract Treatment of terminal alkynes with phenyl selenocyanate in dichloromethane in the presence of CuX(X=CN or Br) and triethylamine at room temperature gave 1-phenylseleno-1-alkynes in high yields.

Addition des organocadmiens aux composés carbonylés α,β-éthyléniques: étude des réactions compétitives des énolates intermédiaires

We have formerly investigated the reactions of organocadmium compounds (in the presence of magnesium halides) with α,β-unsaturated carbonyl compounds. The results show that 1,2 and 1,4-addition reactions take place, however, the cadmium compounds favour 1,4-addition in many cases. The primary “1,4-enolates” can add to the original α,β-unsaturated carbonyl compound: they undergo 1,4-addition to ketones giving δ-diketones; and 1,2-addition to aldehydes thus forming an alcoholate with an aldehyde group which then condenses with the organocadmium compound. The final product is an unsaturated β-glycol. With “1,2-alcoholates”, however, we did not observe such reactions. We have studied the influence of various factors on the course of these reactions. Thus, in the presence of CuX, the 1,4-addition product is predominant and only small amounts of 1,4-addition products from enolates are formed.

Bromokomplexe des Kupfers in Acetonitril

AbstractIt is deduced from absorption spectra and susceptibilities of acetonitrile solutions containing CuII and bromide, that the lower complexes CuBr+ and CuBr2 are unstable with respect to CuI, elementary bromine and CuBr3−. The complex CuBr3− has a low tendency to add another bromide to form CuBr42−. A number of spectral data show that quite generally in organic solvents such as acetonitrile, ethyl acetate, acetic acid, nitromethane and dimethylformamide the trihalogeno‐complex CuX3− can exist in the presence of CuX+, whereas CuX2 is unstable with respect to the mono‐ and the tri‐complex.