Advanced Synthesis & Catalysis最新文献

Developing sustainable and energy-efficient methods for hydrogen production is vital for advancing clean energy technologies. One of the major challenges in water electrolysis is the high overpotential and sluggish kinetics of the oxygen evolution reaction (OER), which significantly limits overall efficiency. This study explores the use of alternative oxidation reactions—specifically, the hydrogen peroxide oxidation reaction (HPOR) and methanol oxidation reaction (MOR)—as promising substitutes to overcome the limitations of OER. Electrochemical investigations revealed that the catalyst exhibited a high Tafel slope of 126.0 mV/dec and an onset potential of 1.60 V versus RHE for OER. The highest current density of 0.93 mA/cm² is obtained at a potential of 1.67 V versus RHE, underscoring the slow reaction kinetics of OER. By comparison, MOR achieved an onset potential as low as 1.46 V versus RHE at a methanol concentration of 1.17 M, bringing a maximum current density of 8.21 mA/cm²—nearly nine times higher than OER—with a lowered Tafel slope of 75.0 mV/dec. Importantly, MOR required 180 mV less potential to accomplish the similar current density (0.93 mA/cm²) as OER. HPOR showed even greater promise, initiating oxidation at an onset potential of just 0.97 V versus RHE and attaining a maximum current density of 10.13 mA/cm² at 1.37 V versus RHE. The potential required for HPOR to reach the same current density as OER was reduced by 650 mV, and its Tafel slope fall further to 55.9 mV/dec at a H₂O₂ concentration of 0.46 M, indicating highly favorable reaction kinetics. Stability tests confirmed that the catalyst maintained robust performance for both MOR and HPOR over extended periods. Nevertheless, the findings highlight that both MOR and HPOR are promising pathways to improve the efficiency of hydrogen production by providing viable, lower-potential alternatives to the conventional OER.

Visible-light photoredox catalysis offers a promising approach to convert indoles into functionalized indoles and indolines under mild conditions. However, existing methods often rely on iridium or ruthenium polypyridyl photocatalysts, which suffered from sustainability concerns and limited scope. Here, we report a transition-metal-free protocol for diverse indole transformations using catechol-derived organic photocatalysts that feature balanced redox potentials and broad reactivity. Three mechanistically distinct transformations of indoles including aerobic bromination, dearomative carbamoylation, and dearomative reduction or detosylation have been achieved under net oxidative, redox-neutral, and net reductive conditions, respectively. A variety of bromoindoles, carbamoyl-indolines, and functionalized indolines or free N–H indoles are obtained in good yields under mild, transition-metal-free conditions. This article provides a sustainable and versatile entry to indole transformations.

A mild and efficient method for the synthesis of β-carbolines has been developed, based on a visible-light-induced cascade cyclization and aromatization of tryptophan derivatives, enabling the key C-ring formation within the tricyclic core structure. Instead of traditional acid-promoted conditions, a neutral photoredox catalyst is employed, and the reaction is carried out under mild, acid- and base-free conditions. A variety of β-carboline frameworks can be efficiently accessed through this streamlined one-pot strategy employing a ruthenium-based photocatalyst.

Electron donor–acceptor complex formation between malononitrile-like substrate and α-keto carboxylic acids happens via a hydrogen bond which facilitates hydroacylation reaction without any exogenous photocatalyst. A variety of substituted benzylidene malononitrile and α,β-unsaturated ketones were efficiently hydroacylated utilizing α-keto acids as both the acyl and hydrogen atom source. The transformation proceeds smoothly under mild reaction conditions, with carbon dioxide being the sole byproduct. Mechanistically, the reaction is driven by a charge transfer transition that generates the acyl radical upon decarboxylation of α-keto carboxylic acid, driving the reaction via a radical pathway.

Halogen bonding is an attractive tool in organic chemistry; however, chiral catalysts bearing halogen bond donor functionalities remain underexplored. Herein, we investigate the development and catalytic applications of binaphthyl-based chiral bromonium and iodonium salts. While previously reported catalysts have been successfully applied in several transformations, their utilization in the construction of vicinal chiral tetrasubstituted carbon stereogenic centers remains challenging. The introduction of bulky substituents into the core structure is an effective methodology for designing chiral catalysts. In this study, chiral halonium salts bearing bulky silyl ether substituents were synthesized and employed as halogen bonding-driven catalysts for the challenging formation of vicinal chiral tetrasubstituted stereogenic centers, affording the corresponding products in high yields and up to 92% ee.

Two complementary catalytic strategies for the N-arylation of sulfoximines using bench-stable aryl thianthrenium salts are reported. A Pd/RuPhos system efficiently promotes coupling under mild thermal conditions, while a visible-light-induced Ir/Cu dual-catalytic system operates at room temperature via a radical pathway. Both methods are scalable, tolerate a wide range of functional groups, and provide practical access to N-aryl sulfoximines, highlighting the tunable reactivity of aryl thianthrenium salts in polar and radical manifolds.

The selective reduction of atmospheric nitrogen to ammonia under ambient conditions via electrochemical methods has emerged as a promising alternative to the Haber–Bosch process. Despite its feasibility, the performance of core catalysts has been constrained by the strength of the π-backdonation between the d-orbital electrons of the metal active center and the antibonding orbitals of nitrogen. In this study, we propose constructing M-N₃ structures and introducing auxiliary metals to cooperatively regulate the local crystal field to enhance the π-backdonation and promote nitrogen activation. By employing machine learning (ML) to analyze the electronic structure and using the number of d electrons and electronegativity of the metal as key descriptors, we successfully established a quantitative relationship between the π-backdonation strength, catalytic activity and identified tungsten and molybdenum as high-performance candidate metals. The corresponding graphene-based catalysts were successfully prepared experimentally, with the tungsten-based catalyst achieving an ammonia production rate of 150.08 μg h⁻¹ mg_cat⁻¹ and a Faraday efficiency of 85.7% at −0.9 V vs. RHE. Density functional theory (DFT) calculations jointly confirmed that the strategy of regulating the local crystal field effectively optimized the d-orbital energy level splitting and electron occupation, promoting the formation of the π-backdonation. This work demonstrates the effectiveness of the crystal field engineering strategy in modulating d-orbital electrons through machine learning and DFT calculations and confirms the unique guiding role of machine learning in the reverse design of high-performance electrocatalysts.

Transition-metal-catalyzed CH activation has emerged as a powerful tool for constructing diverse heterocycles and efficiently increasing molecular complexity in a single operation. Compared with the well-studied diyne [2 + 2 + 2] cycloaddition, diyne-involved CH functionalization represents a promising evolution of this field. The inherent reactivity of diynes enables sequential participation of both alkyne units in relay processes, a feature central to their utility. Recent years have witnessed remarkable progress in diyne-based CH functionalization/cyclization with exquisite site- and chemoselectivity, spanning substrate control strategies, catalysis design, reaction development, mechanistic insights, substrate scope, and practical applications. Organized by the type of diyne and reaction patterns, this review highlights recent advances in transition-metal-catalyzed tandem CH functionalization/cyclization reactions of 1,6-diynes, 1,5-diynes, 1,4-diynes, and other tethered diyne substrates, with a focus on the assembly of 1,3-dienes, polycyclic aromatic hydrocarbons, π-conjugated polymers, polyheterocycles, and related structures. Notably, this review focuses exclusively on reactions where both alkyne units participate in tandem processes, excluding cases where only one alkyne acts as a π-coupling reagent.

Radical–polar crossover (RPCO) has emerged as a powerful synthetic strategy, using the complementary properties of both radical and classical polar chemistry. Radical–polar crossover, especially its oxidative radical–polar crossover (ORPCO), facilitates efficient asymmetric synthesis by converting radical intermediates to carbocations, which allow the formation of enantioselective bonds. This ability to form CC, CO, and CN bonds underlines its significant potential for late–stage functionalization of complex molecules and for diversification of medicinal products. This review summarizes the recent developments in the asymmetric ORPCO domain, including catalytic strategies, transformation mechanisms, and current characteristics. Research into new catalytic strategies and asymmetric bonding paradigms is an important frontier of future research, with the potential to significantly increase the scale and usefulness of ORPCO reactions.

The mechanochemical synthesis of 4,5-dihydro-1,3-thiazol-2-amines and 1,3-thiazolidine-2-imine hydrochlorides has been performed starting from chloroalkyl isothiocyanate and amines in the presence of potassium carbonate. The proposed procedure is efficient under transition metal- and solvent-free ball-milling conditions with the use of a mixer mill. The reactions are selective and show no significant decrease in yields across a broad scope of substrates bearing different functional groups. Moreover, the successful 1 g scale-up experiment demonstrates the practical applicability of the method.