Mechanistic investigations of Co(II)-Catalyzed C-N coupling reactions

Adaptive Photochemical Amination via Co(II) Catalysis

Transition-metal-catalyzed amination of aryl halides is one of the most employed methods for constructing N-arylation adducts. However, the broad success of these reactions largely relies on the screening of precatalysts, elaborated ligands, and case-by-case optimization of reaction conditions (solvent, base, additive, temperature, etc.) for electronically or structurally diverse nucleophiles. Herein, we report an adaptive photochemical C-N coupling of aryl halides with various nitrogen nucleophiles (aliphatic and aromatic amines, amides, sulfonamides, pyrazoles, and ammonium salts) by Co(II) catalysis under the same reaction conditions (same precatalyst, same ligand, same base, same solvent, same temperature) without the addition of any exogenous photocatalyst. This photochemical amination features a wide substrate scope (>130 examples, up to 95% yield) with excellent functional group tolerance. Mechanistic studies indicate that these C-N coupling reactions may proceed via a Co(I)/Co(III) catalytic cycle.

Visible-Light Copper Nanocluster Catalysis for the C-N Coupling of Aryl Chlorides at Room Temperature

Activation of aryl chlorides in cross-coupling reactions is a long-standing challenge in organic synthesis that is of great interest to industry. Ultrasmall (<3 nm), atomically precise nanoclusters (NCs) are considered one of the most promising catalysts due to their high surface area and unsaturated active sites. Herein, we introduce a copper nanocluster-based catalyst, [Cu₆₁(S^tBu)₂₆S₆Cl₆H₁₄] (Cu₆₁NC) that enables C-N bond-forming reactions of aryl chlorides under visible-light irradiation at room temperature. A range of N-heterocyclic nucleophiles and electronically and sterically diverse aryl/hetero chlorides react in this new Cu₆₁NC-catalyzed process to afford the C-N coupling products in good yields. Mechanistic studies indicate that a single-electron-transfer (SET) process between the photoexcited Cu₆₁NC complex and aryl halide enables the C-N-arylation reaction.

Development of a New Arylamination Reaction Catalyzed by Polymer Bound 1,3-(Bisbenzimidazolyl) Benzene Co(II) Complex and Generation of Bioactive Adamanate Amines

We herein report the preparation and characterization of an inexpensive polymer supported 1,3-bis(benzimidazolyl)benzeneCo(II) complex [PS-Co(BBZN)Cl2] as a catalyst by using the polymer (divinylbenzene cross-linked chloromethylated polystyrene), on which 1,3-bis(benzimidazolyl)benzeneCo(II) complex (PS-Co(BBZN)Cl2) has been immobilized. This catalyst was employed to develop arylamination reaction and robustness of the same reaction was demonstrated by synthesizing various bioactive adamantanyl-tethered-biphenylamines. Our synthetic methodology was much improved than reported methods due to the use of an inexpensive and recyclable catalyst.

Microwave Pyrolysis of Macadamia Shells for Efficiently Recycling Lithium from Spent Lithium-ion Batteries

To reduce harm to the environment and human health and improve economic benefits, the large number of spent lithium-ion batteries that have been produced in recent years need to be reasonably recycled. The purpose of this article is to study a new method, microwave pyrolysis of the shells of macadamia nuts, for efficient recycling of lithium from spent lithium-ion batteries. XRD, SEM, and TGA analyses were used to observe the phase change during roasting. With the help of microwave heating and biomass pyrolysis, the decomposition temperature of Li(Ni_1/3Co_1/3Mn_1/3)O₂ was reduced to 300 °C. Carbonated water-soluble Li₂CO₃ was formed under the action of biochar. Accordingly, the effects of pyrolysis temperature (Pte), biomass dose (bio%), reduction roasting temperature (Rte) and reduction roasting time (Rti) on the leaching rate of lithium were studied, and the results indicated that 93.4% lithium could be leached under the following optimum conditions: bio% = 24, Pte = 500 °C, Rte = 750 °C, and Rti = 25 min. A lattice collapse model and coupling reaction theory explained the benefit of biomass pyrolysis on the decomposition of Li(Ni_1/3Co_1/3Mn_1/3)O₂. Finally, we designed a complete process for recycling the cathode powder of spent lithium-ion batteries. This study can guide industrial production to recover lithium-ion batteries in the future.

Deciphering the mechanism of copper-catalyzed N-arylation between aryl halides and nitriles: a DFT study

The mechanism of the CuI/DMEDA-catalyzed tandem hydrolysis/N-arylation of benzonitrile with aryl iodide was studied using the DFT method.

Ligand-free Cu(ii)-catalyzed aerobic etherification of aryl halides with silanes: an experimental and theoretical approach

Owing to their wide occurrence in nature and immense applications in various fields, the synthesis of aryl alkyl ethers has remained a focus of interest.