Presence Of Copper Catalyst Research Articles

Microwave‐Assisted Copper‐Catalyzed One‐Pot Synthesis of 2‐Aryl/Heteroaryl‐4‐Quinolones via Sequential Intramolecular Aza‐Michael Addition and Oxidation

AbstractA protocol has been developed that allows the synthesis of 2‐aryl/heteroaryl‐4‐quinolones from readily available, affordable starting materials. The reaction proceeds under microwave conditions with moderate to high yields in the presence of copper catalyst. Short reaction time, good functional group tolerance, high atom economy, non‐toxic byproduct and no use of special ligands emphasize the applicability of this method in organic synthesis.

Copper(I)-Catalyzed Formation of Isoquinoline and Quinoline Substituted Isobenzofurans.

An efficient synthetic organic transformation was developed to access isoquinoline-substituted isobenzofurans by reaction of substituted 1,5-diynes with isoquinoline N-oxides. Moderate to excellent yields of isoquinoline-derived isobenzofurans were achieved by formation of a new C-C and two C-O bonds in the presence of copper catalyst in one pot. whereas quinoline-substituted isobenzofurans were obtained when the reaction was conducted using quinoline N-oxides and 1,5-diynes in the presence copper catalyst.

Copper catalyzed decarboxylative coupling between coumarin 3-carboxylic acid and 4-thiazolidinones

An efficient copper-catalyzed decarboxylative cross coupling reaction of coumarin 3-carboxylic acid with 4-thiazolidinones has been developed. The described strategy operated smoothly via subsequent decarboxylation and radical addition in the presence of copper catalyst and oxidant. Various coumarinyl-4-thiazolidinone derivatives were obtained easily in moderate to good yield by employing this strategy. Substrate scope and optimization have been carried out appropriately. Optimization was carried out through various copper catalyst, oxidants, and additives.

Highly Selective Monoalkylation of Active Methylene and Related Derivatives using Alkylsilyl Peroxides by a Catalytic CuI‐DMAP System

AbstractA new approach for highly selective monoalkylation of active methylene and related derivatives using various types of alkylsilyl peroxides in the presence of copper catalysts under mild conditions has been developed to a synthetically useful level. This approach has a wide substrate scope in terms of both active methylene compounds and alkylsilyl peroxides. In addition, nitroalkanes can also be employed for a copper‐catalyzed selective monoalkylation with alkylsilyl peroxides. The participation of radical species was proposed in the present monoalkylation reactions by the mechanistic study.

Copper catalyzed C–O bond formation by direct C–H activation of THF with phenols: an approach to the synthesis of phenyl tetrahydrofuranyl ethers

A direct oxidative transformation of phenol derivatives to the corresponding tetrahydrofuranyl ethers via C–H bond activation, in the presence of copper catalyst and desired products were achieved in good yields using TBHP as an oxidant.

Asymmetric Borylative Coupling of Vinylazaarenes and Ketones Catalyzed by a Copper(I) Complex

Azaarenes are attractive structural units widely found in chiral pharmaceuticals, agrochemicals, and biologically active natural products. An ongoing strategy has been the construction of new chira...

A copper-catalyzed reaction between terminal alkynes, acetylenic esters, and oxiranes: efficient synthesis of 2H-pyran-4-carboxylate

A catalytic reaction between terminal alkynes, acetylenic esters, and oxiranes has been described. This domino transformation serves as a useful sequential and one-pot method for the synthesis of 2H-pyran-4-carboxylate skeletons from the readily available starting materials. In situ-generated copper acetylides treated initially with oxiranes in the presence of copper catalysts and tetrabutylphosphonium salts, followed by addition of propiolates after 60 min to form synthetically important heterocycles.

Copper-Catalyzed Asymmetric Formal Hydroaminomethylation of Alkenes with N,O-Acetals to Access Chiral β-Stereogenic Amines: Dual Functions of the Copper Catalyst

Chiral amines are synthetically versatile intermediates used for the preparation of a wide range of biologically active compounds and drugs. Compared with the well-developed synthesis of α-stereoge...

Copper catalyzed synthesis of aryl/alkyl mixed phosphates from diphenylphosphoryl azides and aliphatic alcohols under mild conditions

An efficient and convenient one-pot protocol is developed to prepare aryl/alkyl mixed phosphates in the presence of copper catalyst under exceptionally mild conditions. A series of versatile, ubiquitous, and inexpensive phosphoryl azides and aliphatic alcohols are combined for the first time ever. Diphenylphosphoryl azide is employed as novel phosphors reagent through an unexpected cleavage of PN bond. The transformation is advantageous with respect to a broad of functional group compatibility and different esterification products are isolated in good to excellent results. This new catalytic system represents a superior platform towards a mild, operationally simple, practical, and scalability alternative to access target molecules. Furthermore, a plausible mechanism is proposed based on insightful mechanistic studies.

Copper promoted C-S and C-N cross-coupling Reactions:The synthesis of 2-(N-Aryolamino)benzothiazoles and 2-(N-Aryolamino)benzimidazoles

The synthesis of 2-(N-aryolamino)benzothiazoles and 2-(N-aryolamino)benzimidazoles has been accomplished in the presence of copper catalyst. These reactions involve C-S and C-N cross-coupling reaction. All electron donating and withdrawing substituent's readily underwent the reaction to give target products in good to excellent yield. In addition, the reaction also gave target product in high yield with bulk scale.

Catalytic Regiodivergent Dearomatization Reaction of Nitrosocarbonyl Intermediates with β-Naphthols.

The divergent reactivity of nitrosocarbonyls in oxidative dearomatization of β-naphthols is reported. In the presence of quinidine catalyst, their reactions with α-unsubstituted β-naphthols proceeded through the N-center to furnish α-imino-β-naphthalenones in high yields. Upon exposure to α-substituted β-naphthols in the presence of copper catalyst, an alteration of regioselectivity was observed to produce α-aminoxylation products. The reaction is scalable, tolerates a wide spectrum of functional groups, and represents a rare example of dearomatization of α-unsubstituted β-naphthols.

Synthesis of 4‐(Iso)Quinolinyl‐3(2H)‐furanones from (Iso)Quinoline N‐oxides and 1,4‐Diyn‐3‐ones: A Comparison of Copper Catalysis and Metal‐free Reaction

AbstractA facile synthesis of (iso)quinolinyl‐3(2H)‐furanones from (iso)quinoline N‐oxides and 1,4‐diyn‐3‐ones in the presence of copper catalyst or under metal‐free conditions was developed. The resulting (iso)quinolinyl‐3(2H)‐furanones could be easily converted to (iso)quinolinyl‐isoxazoles, pyrazoles and polycyclic (iso)quinoline derivatives. In addition, the success in one‐pot, metal‐free synthesis of isoquinolinyl‐3(2H)‐furanone starts from isoquinoline shows the capacity of this method for the metal‐free derivatization of pyridine, quinoline and isoquinoline.magnified image

Cellulose-based click-scaffolds: Synthesis, characterization and biofabrications

Carbohydrates derivatives containing propargyl pending functional groups have been used in medical applications due to their improved chemical, biological, and functional properties.In this work, azide and alkyne pendant functional groups were introduced onto ethyl cellulose (EC) and β-cyclodextrin respectively in order to demonstrate the ability of scaffold formation by click chemistry. Technically, Azido-ethyl cellulose (D.S.Azido 0.19) and 2, 3, 6-O- propargylated β –cyclodextrin were synthesized and characterized as click-triggered candidates. The click-gel scaffold was obtained by mixing the two novel candidates in the presence of copper catalyst. Azido-EC was considered to produce clickable electrospun fibers blended with EC (290–620 nm) at 20 kV in order to functionalized EC substrate bearing azide groups to be amenable towards immobilization of an alkyne-terminated bio-molecules. The biocompatibility assay of the prepared click-triggered candidates showed very high level of viability in the human skin fibroblast cells (HFB4) at concentration 100 μg/ml.

Frontispiece: Copper‐ or Thermally Induced Divergent Outcomes: Synthesis of 4‐Methyl 2H‐Chromenes and Spiro‐4H‐Pyrazoles

An unprecedented divergent transformation of alkyne-tethered N-sulfonyl hydrazones via intermediate 3H-pyrazole, which provides an efficient access to 2H-chromenes and spiro-4H-pyrazoles in the presence of copper catalyst or under thermal conditions, is reported. To the best of our knowledge, this is the only example of sulfonation that goes through a cascade process involving 3H-pyrazole, which is confirmed by X-ray diffraction analysis. For full details see the Communication by L. Qiu, X. Xu et al. on page 6705 ff.

Synthesis of cyclic ethers from diols in the presence of copper catalysts

A number of cyclic ethers, namely tetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxepane, oxocane, and 1,4-oxathiane, have been synthesized in high yields by intramolecular dehydration of diols in the presence of copper-based catalysts.

Copper‐ or Thermally Induced Divergent Outcomes: Synthesis of 4‐Methyl 2H‐Chromenes and Spiro‐4H‐Pyrazoles

An unprecedented divergent outcome transformation of alkyne tethered N-sulfonyl hydrazones is reported, which provides a direct and effective access to 4-methyl 2H-chromene derivatives and spiro-4H-pyrazoles in the presence of copper catalyst or under thermal conditions, respectively. The notable features of this process include readily available starting materials, an inexpensive copper catalyst, mild reaction conditions, broad substrate scope, diverse transformations and potential applications of these generated products. Mechanistic studies indicate that the 3H-pyrazole, which is generated via direct [3+2] cycloaddition, is the communal key intermediate of these two divergent transformations. To the best of our knowledge, this is the only example of sulfonation reaction that goes through a cascade process involving 3H-pyrazole, which was isolated and confirmed by single crystal X-ray diffraction analysis for the first time.

Studies on Preparation and Characterization of Aluminum Nitride-Coated Carbon Fibers and Thermal Conductivity of Epoxy Matrix Composites

In this work; the effects of an aluminum nitride (AlN) ceramic coating on the thermal conductivity of carbon fiber-reinforced composites were studied. AlN were synthesized by a wet-thermal treatment (WTT) method in the presence of copper catalysts. The WTT method was carried out in a horizontal tube furnace at above 1500 °C under an ammonia (NH3) gas atmosphere balanced by a nitrogen using aluminum chloride as a precursor. Copper catalysts pre-doped enhance the interfacial bonding of the AlN with the carbon fiber surfaces. They also help to introduce AlN bonds by interrupting aluminum oxide (Al2O3) formation in combination with oxygen. Scanning electron microscopy (SEM); Transmission electron microscopy (TEM); and X-ray diffraction (XRD) were used to analyze the carbon fiber surfaces and structures at each step (copper-coating step and AlN formation step). In conclusion; we have demonstrated a synthesis route for preparing an AlN coating on the carbon fiber surfaces in the presence of a metallic catalyst.

Synthesis of 2,3‐Disubstituted Quinazolinone Derivatives through Copper Catalyzed C–H Amidation Reactions

AbstractThe synthesis of quinazolinone derivatives was achieved from 2‐iodobenzamide derivatives and various benzylamines, allylamine, and cinnamylamine derivatives through a one‐pot copper‐catalyzed reaction. In this reaction, the amine component (benzylamine/allylamine/cinnamylamine) is N‐arylated with 2‐iodobenzamide derivatives through Ullman coupling, followed by an intramolecular C–H amidation in the presence of copper catalyst.

Carbon dioxide uptake as ammonia and amine carbamates and their efficient conversion into urea and 1,3-disubstituted ureas

Solid mixtures of ammonium carbamate and bicarbonate originating from the CO2 capture by NH3 in water–ethanol solution were converted into urea by heating to 428K for 60–90min. The yield of urea was up to 53% on molar basis. An analogous technique was employed to capture CO2 with 1-aminobutane, 1-amino-2-methylpropane, 2-amino-2-methylpropane, 1-aminooctane, aminocyclohexane and 1,4-diazacyclohexane, in organic solvents as amine carbamates which were separated in the solid state and thermally converted at 423K for 15–16h into 1,3-disubstituted ureas with 30–40% yield on molar scale. The formation of 1,3-disubstituted ureas was 100% selective. The rate of the conversion reaction was significantly improved in the presence of copper catalysts. The identification and quantification of the products in the reaction mixtures were obtained by 13C NMR analysis.

Reaction of 1,2‐Difunctionalized Ethanes with Aryl Iodides in Copper‐catalyzed Cross‐Coupling: Application to Synthesis of Phenols

A series of 1,2‐difunctionalized ethanes, such as ethylene glycol, 2‐aminoethanol, 1,2‐diaminoethane, 2‐dimethylaminoethanol, N′,N′‐dimethylethane‐1,2‐diamine, were investigated to test the reactivity with aryl iodides in the presence of copper catalysts. Under the reaction conditions, they produce the various C‐heteroatom cross‐coupled products. Interestingly, ethylene glycol and 2‐dimethylaminoethanol afforded mainly the phenolic compounds while the others produced different cross‐coupled products. Although ethylene glycol and 2‐dimethylaminoethanol resulted in the same product, their behaviors in the reaction were quite different: ethylene glycol appears to mostly act as the ligand and 2‐dimethylaminoethanol appears to serve as both the ligand and reactant. This finding led to a copper‐catalyzed synthesis of phenols using either ethylene glycol or 2‐dimethylaminoethanol, which can be applied to a variety of aryl iodides, providing an alternative synthetic route to phenols