Directing-group (DG)-free enantioselective functionalization of C(sp3)–H bond has emerged as a powerful tool for the late-stage diversification in synthetic and medicinal chemistry. Herein, we have developed an enantioselective triple C–H bond functionalization method via asymmetric migratory allylic substitution of 1,2-enols enabled by palladium catalysis. The robust nature of the migratory allylic substitution strategy is reflected by a broad scope of both electrophiles and nucleophiles with the control of chemo-, regio- and enantioselectivity. This migratory alkylation method is redox-neutral, with three C(sp3)–H bonds being oxidized for the alkylative functionalization and the original enol unit being reduced simultaneously. Mechanistic studies suggest that each one-carbon migration consists of the sequential β-H elimination and migratory insertion to form a new π-allylpalladium species with the intermediacy of the diene-palladium complex. This method was successfully applied for the synthesis of biologically active substances, (+)-Phenoxanol, (+)-Citralis, and (−)-Citralis Nitrile.
The field of chemistry, across its various subdisciplines, has been significantly enriched by advances in understanding carbon intermediates since the 19th century. Among them, carbenes have evolved from transient intermediates to versatile molecular tools, yet integrating luminescence and stimuli-responsiveness in a single system remains a challenge. We report a lithium-bridged carbene-amide hybrid achieves this bifunctional integration. This architecture exhibits intense fluorescence (luminescence efficiency: ΦPL = 85%) and undergoes reversible two-electron cycling among carbene-amido, radical intermediate, and delocalized carbocation states via stepwise single-electron transfers, as demonstrated by crystallographic, spectroscopic, and computational analyses. The asymmetric redox pathway involves N-centered radical formation during oxidation but bypasses this intermediate during reduction, enabling dynamic interconversion. This redox transformation facilitates the direct and reversible conversion between the carbene and carbocation species in a single mechanistic step. Structural studies reveal lithium coordination geometry and charge delocalization underpinning stability. Bridging exciton engineering and dynamic materials science, the work opens avenues for smart molecular technologies in precision synthesis and optoelectronics.
The 1,2-cis-2-amino-2-deoxyglycoside represents a critical structural motif in numerous bioactive natural products and pharmaceuticals, yet its stereoselective synthesis remains a long-standing challenge. Building on our previous ZnI₂-mediated methodology for constructing 1,2-cis-2-azido-2-deoxy glycosidic linkages, we herein report systematic refinements that substantially enhance the versatility and efficiency of this approach. Key advancements include: (i) Substitution of zinc iodide with zinc triflate [Zn(OTf)₂], a superior Lewis acid catalyst that expands substrate scope to include sterically hindered and electronically deactivated glycosyl acceptors; (ii) Development of a novel glycosyl donor platform superseding the conventional 4,6-O-TIPDS/3-O-TIPS protection patterns, enabling streamlined post-glycosylation deprotection sequences for iterative glycan assembly. These methodological improvements effectively address prior limitations in functional group compatibility and synthetic scalability. Leveraging this optimized protocol as the cornerstone synthetic strategy, we achieved the total synthesis of the Acinetobacter baumannii capsular polysaccharide (CPS) K88 pentasaccharide repeating unit, a structurally complex target containing two consecutive 1,2-cis glucosaminide linkages. This synthetic milestone demonstrates the robustness of our methodology and furnishes essential molecular tools for subsequent immunological investigations of this clinically significant pathogen.
A practical and transition-metal-free synthesis of α-bromo/chloro ketones is developed via sequential 1,2-migration and oxidation of alkynyl tetracoordinate boron species under mild conditions. This method employs readily available N-bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) as halogen sources, achieving high efficiency (up to 95% yield) with operational simplicity. The reaction demonstrates broad functional group tolerance, offering a versatile platform for α-halo ketones.
High quality light-absorbing layers with matched band gaps of sub-cells are crucial for achieving high power conversion efficiency (PCE) in the perovskite/organic tandem solar cells (PO-TSCs). In this work, we systematically optimized the band gaps of wide-bandgap perovskite layer (1.73–1.85 eV) and narrow-bandgap organic active layer (1.34–1.38 eV). An asymmetric small-molecule acceptor, namely SY2 (two F atoms and two Cl atoms), is introduced into the PM6:BTP-eC9 blend to enhance the light absorption, form the fibril network morphology, and facilitate exciton dissociation and transport. By precisely integrating a 1.80 eV perovskite sub-cell and a 1.34 eV ternary organic sub-cell, we achieved a champion PCE of 25.47% for the PO-TSCs based on the well-matched short-circuit current density. Besides, the optimized devices exhibited outstanding long-term stability. Our findings highlight the importance of band gap matching between front and near sub-cells in reducing recombination loss for high-performance tandem solar cells.
Although 1,4-Pd migration has been widely used for the functionalization of remote C−H bonds, intermolecular double C−H annulation via this strategy remains elusive. Furthermore, catalytic reactions involving 1,5-Pd migration are scarce due to competitive reductive elimination pathway. Herein, we report an intermolecular double C–H annulation of N-(2-bromophenyl)-2-phenylacrylamides with 1,n-diynes mediated by 1,4-Pd or sequential 1,4/1,5-Pd migrations. The reaction proceeds through sequential Heck cyclization, alkyl-to-aryl 1,4-Pd migration (or alkyl-to-aryl 1,4-Pd migration followed by aryl-to-aryl 1,5-Pd migration), dual alkyne insertion, and C–H activation, providing efficient access to both indolinone-substituted tricyclic frameworks and tetracyclic indolinones. The method exhibits excellent regioselectivity, and preliminary mechanistic studies support the proposed pathway.
Inorganic ionic compounds are widely existed in nature and applied in construction, energy, biomedical and optical fields. However, the inherent ionic bonding characteristics lead to brittle fracture of these inorganic materials under mechanical force, which significantly limits their application scopes. Overcoming the inherent brittleness of these materials represents a long-standing challenge in chemistry and materials science. In recent years, significant advances have been made to turn inorganic materials into flexible ones. In this review, we summarize the emerging strategies for enhancing the flexibility (e.g., deformability, resilience, plasticity, ductility, etc.) of inorganic materials composited by inorganic ionic compounds, by the regulation of bulk solid phase structures and morphologies. For the regulation of bulk solid phase structures, specific strategies involve regulating ionic bonding and slip systems, alongside leveraging dynamic phase transition. Among these, modulating ionic bonds reduces the stiffness of inorganic ionic materials by weakening the interactions between ions, thereby enhancing their moldable ability. Regulating slip systems improves ductility and plasticity by increasing dislocation density and the number of effective slip systems while maintaining the integrity of structure to facilitate slip. Utilizing dynamic phase transition of materials enhances plasticity by dissipating stress through stress- or thermally-induced dynamic cyclic phase transformations. For the regulation of morphologies, approaches focus on constructing nanowires, sub-1 nm architectures, and molecular-scale structures. High aspect ratios and amplified surface effects endow one-dimensional nanowires with exceptional bending flexibility. This feature becomes even more pronounced in sub-1 nm and molecular-scale structures, even imparting polymer-like characteristics. In this review, we aim to deepen the fundamental understanding in turning brittle inorganic ionic compounds to flexible one from a structural-property relationship view, and creates avenues for their potential applications in structural materials, flexible electronics and novel biomaterials.
The construction of functional and robust covalent organic frameworks (COFs) for gas separation, particularly for the efficient removal of CO2 from propylene (C3H6), is both significant and challenging. Herein, thiadiazole-linked COFs were reported by postsynthetic modification (PSM) of hydrazone-linked COFs with Lawesson's reagent (LR). The as-prepared thiadiazole-linked COFs not only retain porosity and crystallinity but also enhance their chemical stability. Furthermore, both thiadiazole-linked COFs demonstrate excellent C3H6 adsorption capacity. Notably, TDA-Ta-ODH-COF exhibits higher C3H6 adsorption capacity, which can separate C3H6 from the C3H6/CO2 mixture. Dynamic separation results at 298 K and 1 bar indicate that CO2 first breaks through the bed at 80 min/g due to the higher adsorption affinity of C3H6. C3H6 is not detected until 100 min/g. Consequently, this process yields a polymer-grade C3H6 output of 2.01 mmol/g. In addition, TDA-Ta-ODH-COF also has the potential to separate polymer-grade C3H6 from a ternary mixture of C3H6/CH4/CO2 (1/1/1). The observed adsorption disparity originates from the abundant heteroatomic sites (N, O, S) in the thiadiazole-linked COFs, which exhibit distinct adsorption affinities for C3H6, CH4, and CO2. A suitable isosteric heat of adsorption (Qst) provides sufficient driving force for selective capture while facilitating low-cost and efficient regeneration. This work presents a facile protocol for fabricating stable and functional COFs, providing references for gas adsorption and separation applications.
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