Sustainable strategies of C–N bond formation via Ullmann coupling employing earth abundant copper catalyst

Ultrasound-assisted Cu(II) Strecker-functionalized organocatalyst for green azide-alkyne cycloaddition and Ullmann reactions

A new aminonitrile-functionalized Fe3O4 has been synthesized via the Strecker reaction, the designed aminonitrile ligand on the surface of the magnetic core coordinated to copper(II) to obtain the final new catalyst. The fabricated nanocatalyst was characterized by Fourier transform Infrared (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), Vibrating-Sample Magnetometer (VSM), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), and Thermogravimetric Analysis (TGA). The high tendency of nitrogens in the aminonitrile functional group to make a complex with Cu(II) has caused the practical activity of this nucleus in this catalyst. This nanocatalyst performance was investigated in azide-alkyne Huisgen cycloaddition (3 + 2) reaction for achieving to 1,4-disubstituted 1,2,3-triazoles in water as a green media at room temperature. In another try, Classic Ullmann Reaction was investigated for the synthesis of biaryls at 85 °C promoted by ultrasonic condition (37 kHz). The reaction scope was explored using different reactants and the results of using this developed catalytic system demonstrated its capacity to reduce the reaction time and enhance the reaction efficiency to provide good to excellent product yield. Conversely, the simple recycling and reusability of this catalyst for at least six times without any noticeable leaching of copper makes it a potential future catalyst for synthesizing such compounds.

Catalytic Amination of Alcohols Using Diazo Compounds under Manganese Catalysis Through Hydrogenative N-Alkylation Reaction

Sustainable chemical production requires fundamentally new types of catalysts and catalytic technologies. The development of coherent and robust catalytic systems based on earth-abundant transition metals is essential, but highly challenging. Herein, we systematically explored a general hydrogenative cleavage/N-alkylation tandem of cyclic and acyclic diazo (N=N) compounds to value-added amines under manganese catalysis. The reaction is catalyzed by a single-site molecular manganese complex and proceeds via tandem dehydrogenation, transfer hydrogenation, and borrowing hydrogenation strategies. Interestingly, the reaction involves abundantly available renewable feedstocks, such as alcohols, that can act as (transfer)hydrogenating and alkylating agents. The synthetic application of our approach in large-scale pharmaceutical synthesis and easy access to highly demanding N-CH3 /CD3 derivatives are also demonstrated. Kinetic studies show that the reaction rate depends on the concentration of alcohol and Mn-catalyst and follows fractional orders. Several selective bond activation/formation reactions occur sequentially via amine-amide metal-ligand cooperation.

Copper-Catalyzed Reactions of Aryl Halides with N-nucleophiles and Their Possible Application for Degradation of Halogenated Aromatic Contaminants

This review summarizes recent applications of copper or copper-based compounds as a nonprecious metal catalyst in N-nucleophiles-based dehalogenation (DH) reactions of halogenated aromatic compounds (Ar-Xs). Cu-catalyzed DH enables the production of corresponding nonhalogenated aromatic products (Ar-Nu), which are much more biodegradable and can be mineralized during aerobic wastewater treatment or which are principally further applicable. Based on available knowledge, the developed Cu-based DH methods enable the utilization of amines for effective cleavage of aryl-halogen bonds in organic solvents or even in an aqueous solution.

C-N, C-O and C-S Ullmann-Type Coupling Reactions of Arenediazonium o-Benzenedisulfonimides

Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Cu(I) catalysed Ullmann-type coupling. The synthetic protocols are mild and easy, and produced either N-alkylanilines, aryl ethers, or thioethers in fairly good yields (18 positive examples, average yield 66%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. It is noteworthy that diazonium salts have been used as electrophilic partners in the Ullmann-type protocol for the first time.

Cu/Mn catalyzed C-N cross coupling reaction of aryl chlorides and amines promoted by PAMAM dendrimer

A bimetallic catalytic combinations of Mn(OAc)2 and Cu(OAc)2 was found to be significantly effective for the Buchwald type C-N cross coupling of arylchlorides and amines. Reaction is highly influenced in the presence of a promoter Poly(amidoamine) (PAMAM) dendrimer which also possesses the advantages of being stabile, non-toxic, biocompatible, non-immunogenic and acts as soluble support for transition metal complex. Although, Mn is low cost and environmentally benign, but it is not fully exploited due to its low intrinsic catalytic activity. Here, the catalytic potential of Mn was drastically increased in the presence of another metal salt (Cu(OAc)2). In bimetallic composition, Mn significantly influences the activity, selectivity and plays a vital role in catalysis. Herein, we have developed a novel, green and economical procedure for the Buchwald type C-N cross coupling of arylchlorides and amines. Presented coupling method works under aerobic and solvent-free conditions and produces an excellent yield of value-added N-arylated or alkylated products.

Ullmann homocoupling of arenediazonium salts in a deep eutectic solvent. Synthetic and mechanistic aspects

DES is exploited as a solvent media in Ullmann homocoupling of arenediazonium salts. Computational study supported by Raman spectroscopy is presented, aiming to elucidate the reaction mechanism.