Advanced Synthesis & Catalysis最新文献

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.