ACS Organic & Inorganic Au最新文献

A novel copper-(I)-anchored covalent organic polymer (Cu⁺@COP) is presented as a robust, heterogeneous catalyst for copper-catalyzed azide-alkyne cycloaddition (CuAAC), operating without the need for external reducing agents or observable copper leaching. Cu⁺ stabilization is achieved via multidentate N,O-ligand coordination within the polymer matrix, enabling high catalytic efficiency (up to 95% yield) and recyclability. Structural, spectroscopic, and ICP-OES analyses confirm Cu presence, offering an alternative to traditional CuAAC protocols. This system combines operational simplicity, reduced waste, and green chemistry principles, positioning Cu⁺@COP as a practical catalyst for applications in synthetic and materials chemistry.

Phosphine-mediated nucleophilic substitution reactions of alcohol substrates, such as the Appel and Mitsunobu reactions, have found widespread applications in chemical synthesis. However, their reliance on stoichiometric chemical oxidants (e.g., carbon tetrachloride and azodicarboxylate reagents) often results in limited functional group tolerance, environmentally hazardous wastes, and unsatisfactory reaction economy. Herein, we describe a user-friendly electrochemical Appel reaction employing readily available tetrabutylammonium halide salts ( ⁿ Bu₄N⁺X^-, X = Cl, Br, and I) as the halogen source. A survey of alcohol substrates revealed broad functional group tolerance, including complex pharmaceutical and bioactive scaffolds. Electroanalytical voltammetry and control experiments support a halide-coupled phosphine oxidation pathway under mild anodic potentials, affording key alkoxyphosphonium intermediates prior to nucleophilic substitution. Notably, the electrochemical halogenation conditions can also facilitate intramolecular alcohol etherification with oxidation-sensitive phenols and weakly acidic alcohol nucleophiles.

Carbofunctionalization of alkynes with trifluoromethylsulfonate nucleophiles is a powerful strategy for the synthesis of vinyl triflates with diverse molecular complexity. However, stereoselective protocols are challenging to realize, and the development of novel strategies for controlling the selectivity is highly desirable. In this work, we show that gold complexes bearing the hemilabile MeDalPhos ligand (MeDalPhos = di-(1-adamantyl)-2-dimethylamino-phenylphosphine) catalyze the E-stereoselective carbofunctionalization of internal alkynes using aryl/vinyl iodides and AgOTf as simple starting reagents. Based on the outer-sphere nature of this reaction and the beneficial effect of the MeDalPhos ligand, the Z-selective attack is practically suppressed, leading to an ideal kinetic selectivity. Mechanistic studies, both experimental and theoretical, revealed that the interplay between kinetics and thermodynamics is crucial in determining the final E/Z ratios for each substrate.

Selective functionalization of C-(sp³)-H bonds remains challenging yet crucial for researchers. A frequently used approach by chemists to tackle this challenge involves leveraging 1,2-metal migration/insertion, which enables the selective activation and cleavage of a specific C-(sp³)-H bond adjacent to or distant from the directing group. Palladium is among the most commonly employed catalysts for C-(sp³)-H functionalization through metal migration/insertion, with Pd-(OAc)₂ being the predominant palladium complex utilized in these processes. 1,2-Palladium migration is a key strategy for achieving selective C-(sp³)-H functionalization. After palladium coordinates to a directing group, its migration can activate the nearby C-(sp³)-H bond. With subsequent migrations, more distant C-(sp³)-H bonds can be targeted and transformed into C-(sp³)-functional groups. During the 1,2-insertion of palladium, the migration of palladium takes place following the activation of the C-(sp³)-H bond. This migration step typically involves the palladium inserting into a double bond, which links the C-(sp³)-H bond to a C-(sp²)-H bond, thereby progressing the reaction. Ultimately, this review highlights that C-(sp³)-H functionalization via 1,2-palladium migration/insertion has the potential to selectively modify both proximal and remote C-H bonds in organic molecules, offering a valuable tool for researchers to synthesize a wide range of organic compounds in future studies. This account encompasses all types of 1,2-palladium migration/insertion and examines their impact on C-(sp³)-H functionalization. It provides a detailed analysis of the mechanisms involved and explores how these migrations enable the activation of both remote and proximal C-(sp³)-H bonds with the directing group.

Cationic Au-(I) complexes of indoles embedding Buchwald phosphine ligands are described. A study combining NMR and X-ray crystallography is described in order to understand the nature of the coordination of the cationic Au atom to the C2-C3 double bond of indoles. Our studies reveal an intermediate coordination between η² and η¹, demonstrated by a strong sp³ character of the C3 atom and a significant slippage toward the C3 atom of the indole rings.

Arylazo sulfones represent a valuable class of organic compounds, which can be exploited as safer and bench-stable analogues of diazonium salts. Notwithstanding their significant applications in light-triggered reactions as precursors of either diazenyl or aryl radicals, their reactivity as 1,3-dipole acceptors has been poorly investigated. The present manuscript addresses the study of a [3 + 2] cycloaddition reaction between arylazo sulfones and α-acidic isonitriles such as TosMIC and related analogues. Reaction conditions have been optimized in a micellar medium, namely CTAC 2% aq solution, in order to afford sustainable synthetic access to 1,2,4-triazole derivatives, a relevant scaffold in medicinal and material chemistry. The substrate scope has been showcased with 24 examples (24-90% yield) with good functional group tolerability. Worthy of note, solution NMR techniques have been applied to characterize the reaction at the molecular level, providing a groundwork to drive a rational choice of the micellar medium on the basis of the substrates' chemical nature. Moreover, the recyclability of the micellar medium was investigated via dynamic light scattering (DLS) analyses.

In this study, a diverse range of short azapeptides and azapeptoids incorporating -CH₂CF₃ or -CH₂CF₂H groups was synthesized. The key strategy involved coupling fluorinated hydrazines with amino acids using acyl chloride derivatives or triphosgene activation. Structural and conformational analyses were conducted by using NMR spectroscopy and X-ray diffraction, revealing the impact of these fluorinated moieties on the overall molecular architecture. Crystallographic studies highlighted a preferential type II β-turn conformation with influences from short hydrogen bonding and fluorine-hydrogen interactions.

We describe the first comparative data on metal-mediated C-H activation and functionalization reactions at two-carbon-atom legacy refrigerants and density functional theory (DFT) analyses on the resulting organometallic products. We reveal that, depending on the degree of fluorination in the refrigerant, C-H activation could lead either to stable M-(H)-R_f products or to a M-(fluoroolefin) complex. The first example of a metal-mediated dehydrofluorination of R-143a is described, resulting from a β-fluoride elimination reaction of a putative [Ir-(H)-(CH₂CF₃)] intermediate and the loss of hydrogen fluoride. This work also reports the first examples of metal-mediated activation of R-125 (CF₃-CF₂H) and R-134a (CF₃-CFH₂) where the direct C-H activation products can be observed spectroscopically and, in the case of R-125, structurally characterized. The stability of the [Ir-(H)-(R_f)] complexes is notable, given that the direct products of C-H activation of nonchelating alkanes at transition metals remains relatively rare. The clean formation of isolable [Ir-(H)-(R_f)] complexes is expected to facilitate studies of migratory insertion reactions in these species, which bodes well for efforts to repurpose high-global-warming-potential legacy refrigerants. Finally, DFT calculations provide insight into how the degree of fluorination affects CC bond lengths and energies of propellor-like rotations in the coordinated fluoroolefins, the relative free energies of fluoroolefin binding, and the role of observed CH···F contacts in the calculated structures.

A new method for the synthesis of cyclometalated gold-(III) complexes featuring (P^N^C) ligands is reported. This protocol employs a tandem oxidative addition/cycloauration process, enabling the formation of (P^N^C)-gold-(III)-aryl, -alkenyl and -alkynyl derivatives by creating two Au-C bonds in one pot from a structurally diverse range of C-(sp²)- and C-(sp)-iodide substrates. Additionally, a complementary two-step method was developed to access (P^N^C)-gold-(III)-alkynyl complexes, which exhibit emission in the blue and green light regions.