Chinese Journal of Chemistry最新文献

The enantioselective construction of bis-heterocyclic frameworks containing pyrroline and indole motifs is achieved through a cooperative palladium-catalyzed tandem process. This methodology efficiently couples oxime esters and 2-alkynylanilines via a sequential Narasaka-Heck cyclization/Cacchi coupling reaction, providing direct access to complex chiral architectures in high yields with excellent enantioselectivity. The protocol demonstrates broad substrate scope and functional group tolerance. A diverse range of oxime esters, bearing both electron-donating and electron-withdrawing groups, as well as heterocyclic and polyarene substituents, undergo the transformation smoothly, delivering the desired products in 80%–96% yields and up to 98% ee. The reaction also accommodates various ortho-alkynylanilines with para-, meta-, and even sterically demanding ortho-substituents, yielding products with high stereocontrol. Preliminary mechanistic investigations reveal that the reaction is facilitated by a single palladium catalyst operating in synergy with two distinct supporting ligands. The system features two concurrent catalytic cycles: a Pd/Sadphos cycle that drives the enantioselective Narasaka-Heck cyclization of the oxime ester to form the pyrroline ring, and a Pd/Xantphos cycle that mediates the anti-aminopalladation (Cacchi reaction) of the 2-alkynylaniline to construct the indole core. A key transmetallation step between the alkyl-Pd(II) and alkenyl-Pd(II) intermediates from the respective cycles enables the coupling, followed by reductive elimination to furnish the final bis-heterocyclic product. The synthetic utility is highlighted by a gram-scale synthesis without erosion of yield or enantioselectivity, and the product could be readily derivatized to other valuable chiral nitrogen-containing scaffolds. This work establishes a streamlined and efficient route to enantioenriched bis-heterocycles, showcasing the power of single-metal, dual-ligand cooperative catalysis in complex molecule synthesis.

Transition-metal-catalyzed radical-mediated four-component carbonylation reactions offer a sustainable and efficient strategy for modular synthesis of complex carbonyl compounds from simple feedstocks. However, current studies have primarily focused on the alkylcarbonylation of π-bonds in unsaturated hydrocarbons, including alkenes, alkynes and 1,3-enynes. In this study, we report a nickel-catalyzed 1,3-alkylcarbonylation of σ-bonds in bicyclo[1.1.0]butanes (BCBs) using CO as an economical carbonyl source. By leveraging steric hindrance and ring-strain effects, the reaction of BCB-tethered esters, activated alkyl bromides and arylboronic acids proceeded efficiently under nickel catalysis and ambient CO pressure, affording a series of aryl cyclobutyl ketones containing a quaternary carbon center. This protocol is characterized by mild reaction conditions, a broad substrate scope, and excellent functional group compatibility. Control experiments revealed that the steric profile of tertiary alkyl radicals is paramount for the chemoselectivity of this four-component carbonylation cascade.

An expedient organophosphine-mediated skeletal editing of benzodithiol-3-ones is demonstrated herein, which represents the first example for metal-free transformations of benzodithiol-3-ones via S-to-C atom swap. This unprecedented formal [4+1] cycloadditions of benzodithiol-3-ones and α-halocarbonyls enable divergent synthesis of diverse 3-hydroxybenzo[b]thiophenes and benzo[b]thiophen-3(2H)-ones, the products of which were determined by the substitution pattern of the α-halocarbonyls. The newly-developed S-to-C exchange strategy allows for the streamline assembly of valuable sulfur-heterocycles via sulfur-deletion and carbon-insertion. This method is distinguished by its transition-metal-free nature, elimination of inert gas protection requirements, convenient operation, mild conditions, extensive substrate generality and decent yields. Of note, the current protocol could be readily applied to late-stage diversification of structurally varied bioactive molecules, underscoring the potential applicability and practical utility of this metal-free skeletal editing strategy.

High catalytic efficiency is a fundamental prerequisite for the industrial adoption of catalytic transformations. However, reactions achieving turnover numbers (TONs) exceeding 10,000 remain rare in photocatalytic areas, which is primarily attributed to insufficient photostability and light-absorption capacity of photocatalysts. Metalloporphyrins, featured by extended π-conjugation systems, exhibit distinct advantages including high molar extinction coefficients, long-lived triplet excited states, and exceptional photostability, alongside distinctive Soret and Q absorption bands. Motivated by these advantageous properties, we herein report a photoinduced cobalt(II) porphyrin-catalyzed aerobic oxidative coupling of phosphorus ylides to synthesize 1,4-enediones. This photocatalytic system is distinguished by an exceptionally low catalyst loading (2.5 × 10^–3 mol%) and achieves a high turnover number (TON) of up to 19,800. Furthermore, capitalizing on the distinct light absorption of cobalt porphyrin across its Soret and Q bands (corresponding to blue and green light regions), a wavelength-regulated stereoselective synthesis of either (Z)- or (E)-1,4-enediones was realized. Besides, benefiting from the strong absorption at the Soret band of cobalt porphyrin, the reaction for (Z)-1,4-enediones proceeds rapidly within 0.5 h under blue LED irradiation, affording a turnover frequency (TOF) of up to 39,600 h^–1. The protocol also demonstrates broad substrate scope, accommodating diverse heterocycles including indoles, thiophenes, and thiazoles. Mechanistic studies implicate the involvement of singlet oxygen (¹O₂) and superoxide anion (O₂•^–), supporting a sequential pathway involving initial oxidation of the phosphorus ylide to a 2-oxo-2-arylacetaldehyde intermediate, followed by a Wittig reaction to yield the (E)-alkene. Subsequent blue LED-induced isomerization then furnishes the (Z)-configured isomers. This study underscores the significant potential of metalloporphyrins as highly robust and efficient photocatalysts for advanced organic synthesis.

Achieving high electrical conductivity through doping without compromising the Seebeck coefficient remains a fundamental challenge in organic thermoelectrics, owing to the intrinsic trade-off between the two parameters. Here, we propose a rational molecular design strategy to enhance the charge delocalization by substituting thiophene with selenophene in donor-acceptor (D-A) type of conjugated polymers based on benzo[1,2-b:4,5-b']dithiophene (BDT) and diketone-functionalized benzo[1,2-c:4,5-c']dithiophene (BDD) units. The selenophene substitution, combined with backbone planarization via a phenyl substituent, increases the charge localization length from ~7 nm to ~11.5 nm. These structural modifications result in a significant improvement of electrical conductivity, from ~78 S cm^–1 to ~148 S cm^–1, while maintaining a high Seebeck coefficient, leading to a maximum power factor exceeding 130 μW·m^–1·K^–2. These results highlight selenium-driven charge delocalization as a promising approach to modulating charge transport and guide the molecular design of efficient organic thermoelectrics.

Although asymmetric catalytic synthesis via dynamic kinetic resolution has proven to serve as a powerful tool for the efficient preparation of planar chiral pillar[5]arenes, the enantioselective synthesis of highly-functionalized pillar[5]arenes with more than two functional groups remains rarely explored. To tackle with this challenge, here we demonstrate the enantioselective synthesis of tetra-functionalized planar chiral pillar[5]arenes via catalytically four-fold asymmetric Sonogashira coupling, resulting in the successful synthesis of diverse planar chiral pillar[5]arenes with both high functionalization degree and very high enantioselectivities (in most cases, >99% e.e.). Attractively, facile derivatizations of the resultant planar chiral pillar[5]arenes further give access to chiral functional pillar[5]arenes with wide potential applications, making them promising building blocks for practical uses. This work not only enriches the synthetic methods for planar chiral pillararenes with high functionalization degree but also give access to diverse promising chiral building blocks for widespread applications.

Multifunctionalization reactions involving reactive intermediates offer powerful strategies for the rapid construction of complex molecules. Herein, we describe two trifunctionalization reactions of pyrazoleamide-derived metal carbenes. Both transformations are proposed to proceed through a zwitterionic intermediate, formed via nucleophilic attack and pyrazole migration, followed by electrophilic trapping. This approach enables the efficient synthesis of 3-hydroxy-2-oxindole derivatives from isatins and amines in good yields, as well as chiral β-aminoamide derivatives via a Rh/CPA co-catalytic system with excellent enantioselectivity. Importantly, both classes of compounds exhibited significant inhibitory activity against multiple tumor cell lines.

The efficacy of chemodynamic therapy (CDT) is limited by low endogenous H₂O₂ levels, and monotherapy often fails to achieve complete tumor eradication. To overcome these challenges, we constructed a multifunctional nanoplatform named Ti₃C₂T_x@AuPt-FA (MAPF). The key innovation of this work lies in a self-supplementing cascade catalytic cycle. Au/Pt nanozymes provided H₂O₂ to generate ·OH by continuously consuming glucose, thus enhancing CDT. Photothermal therapy could synergistically enhance the effect of CDT. The MAPF platform exhibited high catalytic activity and efficient photothermal conversion (η = 52.8%). It potently induced apoptosis in 4T1 cells in vitro and achieved efficient tumor ablation in vivo. Moreover, MAPF enabled prolonged tumor retention and permitted real-time monitoring via computed tomography (CT) and infrared thermal (IRT) imaging. Safety evaluations confirmed that the platform possessed excellent biocompatibility with no significant systemic toxicity. This work provides a typical self-sustaining nanoplatform that addresses the fundamental limitations of CDT, offering a powerful theranostic strategy with high translational potential for precise breast cancer treatment.

The selective functionalization of unactivated benzylic C–H bonds in arenes and N-heteroarenes remains a pivotal challenge in synthetic chemistry, particularly for constructing oxygen-containing functional groups with precision. Herein, we present an efficient photoredox-catalysis strategy for the selective oxidation of benzylic C(sp³)–H bonds in both aromatic and N-heteroaromatic systems. This protocol employed cyclic hypervalent iodine reagents as a bifunctional platform functioning as hydrogen atom transfer (HAT) agent or radical precursor to facilitate the dual oxidative radical–polar crossover (ORPC) process under mild conditions, wherein water served as either a nucleophilic oxygen donor or quenching agent to initiate the oxidation process.