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Abstract Palladium catalyzed tandem reaction represents a one-pot synthetic approach to efficiently synthesize complex functionalized molecules while reducing synthetic steps, aligning with the principles of green chemistry. However, achieving a direct cascade of the aza-Wacker and Povarov reactions in one-pot synthesis presents a challenge due to substrate compatibility issues between the two reactions. In this work, we describe an aza-Wacker/Povarov reaction employing a highly electrophilic palladium catalyst, which effectively converts anilines and 1,6-dienes into hexahydro-cyclopenta[b]quinolines. The optimized conditions yield up to 79%, with a diastereoselectivity > 20:1. Substrate range testing reveals compatibility with various sensitive functional groups, and successful late-stage modifications are performed on several natural products and drug molecules, demonstrating the versatility and practicality of the method. Additionally, a preliminary investigation into the reaction mechanism suggests an aza-Wacker process followed by a Povarov process.

Abstract Carboxylates are ideal directing groups because they are widely available, readily cleavable and excellent linchpins for diverse follow-up reactions. However, their use in meta-selective C−H functionalizations remains a substantial unmet catalytic challenge. Herein, we report the ruthenium-catalyzed meta-C–H alkylation of aromatic carboxylic acids with various functionalized alkyl halides. A bidentate N-ligand increases the electron density at the metal center of ortho-benzoate ruthenacycles to the extent that single-electron reductions of alkyl halides can take place. The subsequent addition of alkyl radicals is exclusively directed to the position para to the CAr–Ru bond, i.e., meta to the carboxylate group. The resulting catalytic meta-C−H alkylation extends to a wide range of (hetero)aromatic carboxylic acids including benzofused five-membered ring heteroarenes but no pyridine derivatives in combination with secondary/tertiary alkyl halides, including fluorinated derivatives. It also allows site-selective C5−H alkylation of 1-naphthoic acids. The products are shown to be synthetic hubs en route to meta-alkylated aryl ketones, nitriles, amides, esters and other functionalized products.

Abstract Herein, we disclose a highly efficient cobalt-catalyzed cross-electrophile alkynylation of a broad range of unactivated chlorosilanes with alkynyl sulfides as a stable and practical alkynyl electrophiles. Strategically, employing easily synthesized alkynyl sulfides as alkynyl precursors allows access to various alkynylsilanes in good to excellent yields. Notably, this method avoids the utilization of strong bases, noble metal catalysts, high temperature and forcing reaction conditions, thus presenting apparent advantages, such as broad substrate scope (72 examples, up to 97% yield), high Csp-S chemo-selectivity and excellent functional group compatibility (Ar-X, X = Cl, Br, I, OTf, OTs). Moreover, the utilities of this method are also illustrated by downstream transformations and late-stage modification of structurally complex natural products and pharmaceuticals. Mechanistic studies elucidated that the cobalt catalyst initially reacted with alkynyl sulfides, and the activation of chlorosilanes occurred via an S N 2 process instead of a radical pathway.

In this study, 56 isoxazole derivatives were synthesized and their antitumor activity against 9 cancer cells, such as BXPC-3, MiaPaCa-2, PANC-1, MCF-7, HCT-116, HepG2, NCI-H460, A549 and B16 was detected. The results of pharmacological experiments indicated that most compounds exhibit good cytotoxicity against nine cancer cells. Among them, compound 14–3 has an IC50 of 2.4 μM for colon cancer cells HCT-116, which shows the best effect and is better than the broad-spectrum drug 5-Fluorouracil (5-Fu) for the treatment of colon cancer. In addition, 14–3 induces apoptosis and leads to cell cycle arrest in the G2/M phase. Cytotoxicity tests on human normal hepatocytes LO2 also demonstrates that 14–3 is less toxic than 5-Fu with no obvious toxicity. These results suggest that 14–3 is a potential candidate for the development of anti-tumor drugs.

Abstract An unprecedented Et2Zn‐mediated gem‐dicarboxylation of C─C/C─H single bond of cyclopropanols with CO2 is disclosed, which provides a straightforward and efficient methodology for the synthesis of a variety of structurally diverse and useful malonic acids in moderate to excellent yields. The protocol features mild reaction conditions, excellent functional group compatibility, broad substrate scope, and facile derivatization of the products. DFT calculations confirm that the transition‐metal‐free transformation proceeds through a novel ring‐opening/α‐functionalization/ring‐closing/ring‐opening/β‐functionalization (ROFCOF) process, and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) plays dual important roles in the transformation.

Abstract Traditional palladium‐catalyzed dearomatization of (hetero)arenes takes place via an ionic pathway and usually requires elevated temperatures to overcome the energy barrier of the dearomative insertion step. Herein, a combination of the radical and two‐electron pathways is disclosed, which enables room temperature dearomative 3D transformations of nonactivated phenyl rings with Pd(0) as the catalyst. Experimental results together with density functional theory (DFT) calculations indicate a versatile π‐allyl Pd(II) species, cyclohexadienyl Pd(II), possibly is involved in the dearomatization. This species is generated by combining the cyclohexadienyl radical and Pd(I). The cyclohexadienyl Pd(II) provides chemoselective (carboamination and trieneylation), regioselective (1,2‐carboamination), and diastereoselective (carbonyl‐group directed face selectivity) conversions.

Molecular rearrangements are ubiquitous in modern synthetic chemistry, providing a powerful strategy to arrive at complex structures in an atom- and step-economic process. Here, the authors disclose a Mn(I)- catalyzed sigmatropic rearrangement of β, γ-unsaturated alcohols via C-C σ-bond activation to site-selectively reorganize carbon skeletons.

The crystal morphology and conformational changes during crystallization of a polypropylene random copolymer (PPR) are the basis for understanding its crystallization process. In this work, novel rare-earth β-nucleating agent WBN-28 was directly added into PPR to induce β-crystallization. The results of differential scanning calorimetry (DSC) showed that it has an excellent β-crystal-induced effect. The β-crystal content could surpass 85%, calculated from wide-angle X-ray diffraction (WAXD) data. The morphology of the β-crystal and α-crystal was intuitively observed via a polarizing optical microscope (POM). The β-crystallites were interconnected to naturally develop plate-like crystalline regions possessing a certain size, and the α-crystallites with sufficient thicknesses possessed a cross-hatched phenomenon. The bundle-like supramolecular structure of the β-crystal induced by WBN-28 was further observed via a scanning electron microscope (SEM). The conformational changes in the crystallization process of PPR were resolved via high-resolution infrared spectroscopy to understand its β-crystallization in depth. The conformational changes during the crystallization of PPR were found to be different from those of the isotactic polypropylene homopolymer (PPH); they had their own characteristics. This will provide guidance for understanding the β-crystallization of PPR in depth.

Derivatization of azaarenes can create molecules of biological importance, but reductive functionalization of weakly reactive azaarenes remains a challenge. Here the authors show a dearomative, diastereoselective annulation of azaarenes, via ruthenium(II) reductive catalysis.

Pd(II) catalyst turnover by reoxidation of a low valent Pd species is the key step for a Pd(II) catalyzed oxidation reaction. Here, the authors report a new strategy to address Pd reoxidation by fabricating spatially proximate photocatalyst and Pd(II) catalyst into metal-organic framework.

The β-crystals of polypropylene have a metastable crystal form. The formation of β-crystals can improve the toughness and heat resistance of a material. The introduction of a β-nucleating agent, over many other methods, is undoubtedly the most reliable method through which to obtain β-PP. Furthermore, in this study, certain newly developed β-nucleating agents and their compounds in recent years are listed in detail, including the less-mentioned polymer β-nucleating agents and their nucleation characteristics. In addition, the various influencing factors of β-nucleation efficiency, including the polymer matrix and processing conditions, are analyzed in detail and the corresponding improvement measures are summarized. Finally, the composites and synergistic toughening effects are discussed, and three potential future research directions are speculated upon based on previous research.

2-(hetero)aryl N-heteroarenes are ubiquitously applied in numerous fields of science and useful for the development of bioactive molecules and drugs, but there is a lack of general methods for their synthesis. Here, the authors report an iridium(III)-catalyzed method for direct α-arylation of N-heteroarenes with aryl and heteroaryl boronic acids, by a H2O-mediated H2-evolution cross-coupling strategy.

Arene-fused siloles have attracted interest due to their promising applications in electronic and optoelectronic devices. Here, the authors report Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides via α-silyl radical Smiles rearrangement for accessing naphthyl-fused benzosiloles under visible-light photoredox conditions.

Summary: Benzimidazolone constitutes the core structure of numerous pharmaceuticals, agrochemicals, inhibitors, pigments, herbicides, and fine chemicals. Amination of hydrocarbons is an attractive tool for the creation of nitrogen-containing products. However, the multiple steps, harsh conditions, and low atom efficiencies often present in these reactions remain challenging. We present a multicomponent synthesis of functional benzimidazolones from arylamines, dialkylamines, and alcohols, acting via the sequence of copper-catalyzed oxidative tandem C–H aminations and alkyl deconstructive carbofunctionalization. The catalytic transformation forms multiple bonds in one single operation, uses readily available feedstocks and a naturally abundant Cu/O2 catalyst system, has broad substrate scope, avoids pre-installation of aminating agents and directing groups, and provides high chemo- and regioselectivity, resulting in direct functionalization of inert C–H and C–C bonds via single-electron oxidation-induced activation mode. This platform can be expected to provide structurally diverse products with interesting biological, chemical, and physical properties. : Chemistry; Catalysis; Organic Chemistry Subject Areas: Chemistry, Catalysis, Organic Chemistry

Summary: The development of aggregation-induced emission (AIE) building block and deciphering its luminescence mechanism are of great significance. Here a feasible strategy for the construction of AIE unit based on E-Z isomerization (EZI) of exocyclic C=N double bond is proposed. Taking [1,2,4]thiadiazole[4,3-a]pyridine (TZP) derivative as an example, its aryl-substituted derivative (TZPP) shows obvious AIE character. The analysis of spectral data and theoretical calculations indicates that fast structural relaxation of TZPP in the emissive state plays a key role in a low fluorescence quantum yield in dilute solution, which should be caused by the small energy gap between locally excited (LE) state and twisted intramolecular charge transfer state. When in solid state, the bright emission with LE state characteristic reappears due to the large shift barrier of geometry transformation. As a potential building block for AIEgens with special heterocyclic structure, these findings would open up opportunities for developing various functional materials.

Summary: Selective linkage of renewable alcohols and ammonia into functional products would not only eliminate the prepreparation steps to generate active amino agents but also help in the conservation of our finite fossil carbon resources and contribute to the reduction of CO2 emission. Herein the development of a novel 2-(4-methoxyphenyl)-1,8-naphthyridine-based iridium (III) complex is reported, which exhibits excellent catalytic performance toward a new hydrogen transfer-mediated annulation reaction of 2-nitrobenzylic alcohols with alcohols and ammonia. The catalytic transformation proceeds with the striking features of good substrate and functional group compatibility, high step and atom efficiency, no need for additional reductants, and liberation of H2O as the sole by-product, which endows a new platform for direct access to valuable quinazolines. Mechanistic investigations suggest that the non-coordinated N-atom in the ligand serves as a side arm to significantly promote the condensation process by hydrogen bonding. : Inorganic Chemistry; Molecular Inorganic Chemistry; Catalysis Subject Areas: Inorganic Chemistry, Molecular Inorganic Chemistry, Catalysis