Copper-Catalyzed Direct Synthesis of Di- and Triphenylamines: A Dramatic Accelerating Effect of 2-Aminophenols

Multi-Faceted Antimicrobial Efficacy of a Quinoline-Derived Bidentate Copper(II) Ligand Complex and Its Hydrogel Encapsulated Formulation in Methicillin-Resistant Staphylococcus aureus Inhibition and Wound Management

The emergence of antimicrobial resistance, exemplified by methicillin-resistant Staphylococcus aureus (MRSA), poses a grave threat to public health globally. Over time, MRSA has evolved resistance to multiple antibiotics, challenging conventional treatment strategies. The relentless adaptability of MRSA underscores the urgent need for innovative and targeted antimicrobial approaches to combat this resilient pathogen. Ancient knowledge and practices, along with scientific evidence, have established that metallic copper, and its organic coordination complexes can act as potential antibacterial substances. In search of a smart and effective antimicrobial against MRSA, we designed, synthesized, and characterized a bidentate copper(II) ligand complex (SG-Cu) utilizing a comprehensive array of analytical techniques, including ESI-MS, elemental analysis, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and others. Antibacterial efficacy and mechanism of action of the complex were assessed through bacterial growth analyses, bacterial membrane perturbation assays, ROS elicitation assays, and field emission scanning electron microscopy. SG-Cu was found to maintain robust biocompatibility against the mammalian cell lines HEK-293, WI-38, and NIH/3T3. Remarkably, SG-Cu demonstrated significant biofilm disruptive tendency evidenced by the retardation of sliding motility, reduction in slime production, reduction in biofilm viability, and enhanced biofilm eradication, both in vitro and in urinary catheters. In vivo studies on murine excisional wounds, with SG-Cu impregnated in a palmitic acid conjugated NAVSIQ hexapeptide (PA-NV) hydrogel, revealed the sustained release of SG-Cu from the gel matrix, facilitating accelerated wound healing and effective wound disinfection. This multifaceted investigation highlights the potential of SG-Cu as a versatile option for combating MRSA infections and promoting wound healing, solidifying its claim to be developed into a viable therapeutic.

Nickel-Catalyzed N,N-Diarylation of 8-Aminoquinoline with Large Steric Aryl Bromides and Fluorescence of Products

A simple and efficient methodology for the synthesis of large sterically hindered triarylamines in a single step was developed. A direct N,N-diarylation of 8-aminoquinoline with sterically hindered bromides, making use of inexpensive nickel as a catalyst and simple sodium salt as a base, gives the products in good to excellent yields. Various bromides and substituted 8-aminoquinolines are tolerated. Preliminary fluorescence results indicate that these sterically hindered and conjugated triarylamines may have some potential in material chemistry.

2-Aminophenolate ligands for phosphorus(v): a lithium salt featuring the chiral [P(OC6H4NR)3]- anion

Phosphoranes P(OC6H4NR)2(OC6H4NHR) [R = Me (2a), Ph (2b), C6F5 (2c)] were synthesized by treating PCl5 with the respective 2-aminophenol derivative (1a-c, 3.1 equiv.). In one instance, an intermediate species, P(OC6H4NR)2Cl [R = Me (3a)], was isolated and structurally characterized. Deprotonation of the amine moieties (-NH[combining low line]R) in phosphoranes 2a and 2b with a strong alkali-metal base (e.g. n-BuLi) in the presence of a strong-donor solvent (e.g. THF) afforded salts composed of the hexacoordinate P(v)-anions [P(OC6H4NR)3]- (R = Me, [4a]-; Ph, [4b]-). Employing precursor 2a, the salt Li(THF)3fac-[4a]- was isolated. The X-ray crystal of each enantiomer of [4a]- was determined and, to our knowledge, represents the first structurally characterized example of a salt containing a hexacoordinate P(v)N3O3 anion featuring P(v)-N bonds.

Copper(ii)-catalyzed Chan–Lam cross-coupling: chemoselective N-arylation of aminophenols

Copper(ii)-catalyzed boronic acid promoted chemoselective N-arylation of unprotected aminophenols has been developed.

Ligand-Free, Cu- and Fe-Catalyzed Selective Ring-Opening Arylations of Benzoxazoles with Aryl Iodides

Cu- or Fe-based catalyst systems have been reported to selectively catalyze the N,N-diarylation or N-monoarylation of benzoxazoles ring-opening with aryl iodides in the absence of additional added ligand in polyethylene glycol under an inert atmosphere. Two types of coupling products (triphenylamines and diphenylamines) have been examined and the reaction routes can be simply controlled by changing the metal salts (Cu or Fe) as catalyst. A range of substrates have been investigated for the diverse reactions, and the corresponding arylation products were achieved in good to high yields. This selective, low-cost, and environmentally friendly protocol displays great potential for replacing existing methodologies as well as extending the synthetic applications of benzoxazoles.

A general route for synthesis of N-aryl phenoxazines via copper(i)-catalyzed N-, N-, and O-arylations of 2-aminophenols

A novel copper(i)-catalyzed tandem reaction ofN- andO-arylations was developed and a general route for synthesis ofN-aryl phenoxazinesviacopper-catalyzedN-,N-, andO-arylations of 2-aminophenols was established.