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Cyclobutene scaffolds occur in natural products and bioactive compounds. Their unique structural features and intrinsic ring strain make cyclobutene a type of important building block in synthetic chemistry. In recent years, considerable efforts have been dedicated to the synthesis of chiral cyclobutenes. Enantioselective [2+2] cycloadditions and functionalization of cyclobutene derivatives have emerged as powerful and reliable protocols for achieving this goal, resulting in significant progress in this field. This review provides a comprehensive summary of the recent advancements in the asymmetric synthesis of chiral cyclobutenes, and the discussion is logically divided into four parts according to the reaction mode. [ABSTRACT FROM AUTHOR]

Na3V2(PO4)2F3 with a high theoretical energy density, robust 3D structure, and superior thermal stability has become one of the popular cathode materials for sodium ion batteries. Currently, its poor intrinsic electronic conductivity leads to unsatisfactory rate performance, which is still the bottleneck for commercializing sodium-ion batteries. In this work, carbon nanotube–intertwined Na3V2(PO4)2F3 nanospheres (notated as NVPF@CNTs) are successfully synthesized by a solvothermal method and subsequent heat treatment. In NVPF@CNTs composites, the carbon nanotubes constituted a continuous conductive 3D carbon network, realizing the improvement of electrical conductivity. The NVPF nanospheres are exposed to the electrolyte to increase the contact area with the electrolyte and greatly shorten the diffusion distance of Na+. The unique architecture endorses superior electrochemical performance and good reaction kinetics. Thus, the NVPF@CNTs as cathode exhibits good cycling performance (117.6 mAh g−1 at 0.2 C after 300 cycles) and rate capability (73.4 mAh g−1 at 5 C with a high capacity retention ratio of 91.6% after 600 cycles). The excellent electrochemical performance for NVPF@CNTs opens up a new way to achieve high performance of sodium-ion batteries. [ABSTRACT FROM AUTHOR]

In recent decades, transition-metal-catalyzed nucleophilic dearomatization of electron-deficient heteroarenes, such as pyridines, quinolines, isoquinolines and nitroindoles, has become a powerful method for accessing unsaturated heterocycles. This short review summarizes nucleophilic dearomatizations of electron-deficient hetero-arenes with carbon- and heteroatom-based nucleophiles via transition-metal catalysis. A significant number of functionalized heterocycles are obtained via this transformation. Importantly, many of these reactions are carried out in an enantioselective manner by means of asymmetric catalysis, providing a unique method for the construction of enantio-enriched heterocycles. 1 Introduction 2 Transition-Metal-Catalyzed Nucleophilic Dearomatization of Hetero-arenes via Alkynylation 3 Transition-Metal-Catalyzed Nucleophilic Dearomatization of Heteroarenes- via Arylation 4 Transition-Metal-Catalyzed Nucleophilic Dearomatization of Heteroarenes- with Other Nucleophiles 5 Transition-Metal-Catalyzed Nucleophilic Dearomatization with Nucleophiles Formed In Situ 6 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) attract extensive attention as a promising alternative to lithium-ion batteries (LIBs) owing to their abundant reserves and low cost for large-scale energy storage systems. Among the electrode materials for sodium ion batteries, Na3V2(PO4)2F3 (NVPF), with the NASICON structure, has a unique three-dimensional (3D) channel, suitable voltage plateau and high thermal stability. However, it suffers from low intrinsic electronic conductivity. In this work, we successfully synthesize hierarchical hollow NVPF@C microspheres assembled from mesoporous nanosheets, and the possible formation process is systematically explored by changing the reaction time, solvent ratio and glucose dosage. At the same time, these microspheres are wrapped in graphene (marked as NVPF@C@rGO) to further improve their electrochemical performance. As a half-cell cathode, the NVPF@C@10 wt% rGO microspheres exhibit excellent rate performance (95 mA h g−1 at 2C) and cycle stability (78.2% capacity retention after 1500 cycles at 5C). This can be attributed to the hierarchical hollow morphology and graphene packages, which provide continuous electron and ion channels, large electrolyte contact areas and stable structures. This work will provide a viable method for designing high-power NIBs. [ABSTRACT FROM AUTHOR]

Based on the strong enhancement effect of procaterol hydrochloride on the electrochemiluminescence (ECL) of Ru(bpy)32+ (bpy = 2,2′-bipyridine) in an alkaline H3PO4-NaOH buffer solution on a bare Pt electrode, a simple, rapid and sensitive method was developed for the determination of procaterol hydrochloride. The optimum conditions for the enhanced ECL have been developed in detail in this work. Under optimum conditions, the logarithmic ECL enhancement vs. the logarithmic concentration of procaterol hydrochloride is linear over a wide concentration range of 2.0 × 10−7 to 2.0 × 10−4 M ( r = 0.9976), with a limit of detection of 1.1 × 10−8 M (S/ N = 3), and a relative standard deviation of 2.1% ( n = 7, c = 5.0 × 10−6 M). The proposed method was applied to the determination of this drug in tablets with recoveries of 89.7%-98.5%. In addition, a possible mechanism for the enhanced ECL of Ru(bpy)32+, which is caused by ProH, has also been proposed. [ABSTRACT FROM AUTHOR]