Direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride.

A strategy for direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride is described. The reaction of 1-biphenylyl-2-diazo-2-aryl ketones with triflic anhydride proceeded smoothly in the presence of 2,6-di-tert-butylpyridine under mild conditions to produce phenanthrenyl triflates in high to excellent yields. The phenanthrenyl triflate products were demonstrated to be utilized as coupling partners in various coupling reactions. The proposed mechanism involves an intramolecular Friedel-Crafts reaction of a vinyl cation intermediate formed in situ.

Modular access to alkylgermanes via reductive germylative alkylation of activated olefins under nickel catalysis.

Carbon-introducing difunctionalization of C-C double bonds enabled by transition-metal catalysis is one of most straightforward and efficient strategies to construct C-C and C-X bonds concurrently from readily available feedstocks towards structurally diverse molecules in one step; however, analogous difunctionalization for introducing germanium group and other functionalities remains elusive. Herein, we describe a nickel-catalyzed germylative alkylation of activated olefins with easily accessible primary, secondary and tertiary alkyl bromides and chlorogermanes as the electrophiles to form C-Ge and C-Calkyl bonds simultaneously. This method provides a modular and facile approach for the synthesis of a broad range of alkylgermanes with good functional group compatibility, and can be further applied to the late-stage modification of natural products and pharmaceuticals, as well as ligation of drug fragments. More importantly, this platform enables the expedient synthesis of germanium substituted ospemifene-Ge-OH, which shows improved properties compared to ospemifene in the treatment of breast cancer cells, demonstrating high potential of our protocol in drug development.

One-pot synthesis of multisubstituted propenylbenzenes from benzyl chlorides through relay catalysis of palladium.

A strategy for the synthesis of multisubstituted propenylbenzenes using benzyl chlorides as starting materials is described. The palladium-catalyzed allylative dearomatization and the subsequent Wagner-Meerwein rearrangement as well as the olefin isomerization proceeded smoothly under mild conditions to produce propenylation products in good yields with high regioselectivity. Control experiments and cyclic voltammetry analysis suggest that Bu3SnCl, a by-product generated in the first step of allylative dearomatization, plays an essential role in the third step of olefin isomerization in the presence of a Brønsted acid.

Bioleaching performance of vanadium-bearing smelting ash by Acidithiobacillus ferrooxidans for vanadium recovery.

The bioleaching process is widely used in the treatment of ores or solid wastes, but little is known about its application in the treatment of vanadium-bearing smelting ash. This study investigated bioleaching of smelting ash with Acidithiobacillus ferrooxidans. The vanadium-bearing smelting ash was first treated with 0.1 M acetate buffer and then leached in the culture of Acidithiobacillus ferrooxidans. Comparison between one-step and two-step leaching process indicated that microbial metabolites could contribute to the bioleaching. The Acidithiobacillus ferrooxidans demonstrated a high vanadium leaching potential, solubilizing 41.9% of vanadium from the smelting ash. The optimal leaching condition was determined, which was 1% pulp density, 10% inoculum volume, an initial pH of 1.8, and 3 Fe2+g/L. The compositional analysis showed that the fraction of reducible, oxidizable, and acid-soluble was transferred into the leaching liquor. Therefore, as the alternative to the chemical/physical process, an efficient bioleaching process was proposed to enhance the recovery of vanadium from the vanadium-bearing smelting ash.

Unsupported nanoporous gold catalyst for highly selective hydroamination of alkynes.

An efficient and highly selective heterogeneous catalyst system for hydroamination of alkynes was developed using unsupported gold nanopores (AuNPore) for the first time. The AuNPore-catalyzed highly regioselective hydroamination of alkynes proceeded smoothly without any additive and solvent under mild conditions (rt-50 °C) to yield Markovnikov imines in satisfactory to excellent yields. No gold leached from AuNPore during the hydroamination of alkynes. Moreover, the catalyst was easily recovered and reused without any loss of catalytic activity. A one-pot, two-step procedure using a single AuNPore catalyst has been devised to produce secondary amines derived from readily available alkynes and anilines with high atom efficiency.

Remediation of lindane contaminated soil by fluidization-like dielectric barrier discharge.

This study proposed the fluidization-like dielectric barrier discharge (DBD) plasma for the remediation of lindane contaminated soil and integrated physical and chemical reaction pathway. Soil particle distribution within the reactor was simulated with Euler-Euler and Gidaspow drag models, and a bipolar pulsed power supply was applied to energize the DBD reactor after full fluidized. The effect of soil particles movement on electric features was discussed in terms of voltage waveforms and Lissajous figures. Lindane degradation was found to be related to electrics parameters and soil properties. Soil samples before and after treatment were analyzed by XRD and SEM methods. A 95.98% lindane decomposition and 0.66 mgLindane/h average reaction rate were obtained with 3 wt% CaO injection by pulse power drove fluidization-like DBD after 32 min treatment. Ozone was proved to play a major role during lindane degrading by plasma. The reaction potential pathway of lindane decomposition contains 4 steps, including dehydrogen, dehydrochlorination, and dechlorination, respectively.

Mechanochemical treatment for degradation of ciprofloxacin (CIP) in solutions.

Ciprofloxacin (CIP) is a kind of widely used fluoroquinolone antibiotic, and the widespread presence of CIP in aquatic environment has become a serious issue. Mechanochemical treatment (MCT), as an effective approach to degrade persistent organic pollutants, has many advantages of low cost, simplicity, and being environmentally innocuous. However, little attention has been paid to employing MCT to treat effluents containing CIP. In this study, MCT was introduced to degrade CIP in aquatic solutions. A series of CIP degradation experiments were conducted by a planetary ball mill, and the influences of main parameters on CIP degradation efficiency were investigated. Furthermore, an optimum combination was selected through orthogonal experiments, and CIP degradation efficiency could reach as high as 99% in certain conditions. Besides, the biotoxicity of CIP solution was also studied. MCT exhibits satisfying performance for degrading CIP in solutions, which makes MCT a promising approach to CIP elimination and also encourages further applications in treating effluents containing other organic pollutants.

Investigations of S-nZVI/AC composites for hexavalent chromium (Cr(VI)) elimination: synthesis and application.

Sulfidated nano zero-valent iron supported by activated carbon (S-nZVI/AC) composites were synthesized via liquid phase reduction method, and then they were used for Cr(VI) elimination. Characterization results showed that Fe0 was the main component, besides, iron oxides and iron sulfides were also detected. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that S-nZVI nanoparticles were homogeneously distributed on the surfaces of AC. The influences of S/Fe ratio, C/Fe ratio, pH value, reaction temperature and co-existed ions (Cl-, SO42-, PO43- and NO3-) on Cr(VI) removal performances were investigated. Furthermore, the corresponding mechanisms were also discussed. The S-nZVI/AC composites exhibited good aging-resistance performances that Cr(VI) removal efficiency still maintained at 83.1% after being sealed in water for seven days, and they also had satisfying cycling stabilities that Cr(VI) removal efficiency only decreased less than 10% after four cycles. The good performances of S-nZVI/AC composites for Cr(VI) removal are attributed to the protection effect of iron sulfides and immobilization effect of AC, making S-nZVI/AC as a promising candidate for Cr(VI) elimination in effluents.

Sesquiterpene lactones with anti-inflammatory and cytotoxic activities from the roots of Cichorium intybus.

Cichorium intybus L. (Asteraceae), belonging to the tribe Cichorieae of the family Asteraceae, has a long history as an edible and medicinal food. Sesquiterpene lactones are commonly considered as its major active constituents. In the current study, five unreported sesquiterpene lactones, including one 12,8-guaianolide and four 12,6-guaianolides were isolated from C. intybus roots, as well as 16 known analogues. The planar structures and relative configurations of these compounds were elucidated by extensive spectroscopic analysis. The absolute configurations were determined by the time-dependent density functional theory (TDDFT)-based electronic circular dichroism (ECD) calculation method. Bioassay results showed that seven of the isolates exhibited remarkable NO production inhibitory activity in LPS-stimulated RAW264.7 macrophages, with IC50 values ranging from 1.83 to 38.81 µM. Some of them can significantly decrease the secretion of inflammatory cytokines (TNF-α and IL-6). Cytotoxicity assays demonstrated that intybusins B, as well as four known compounds, displayed obvious inhibitory activities against four human tumor cells, with IC50 values ranging from 9.01 to 27.07 µM.

Palladium-Catalyzed Para-C-H Bond Amination of 2-Aryl Chloromethylbenzenes.

Palladium-catalyzed para-C-H bond amination of 2-aryl chloromethylbenzenes is described for the first time. The reactions of 2-aryl chloromethylbenzenes with cyclic amines proceeded smoothly in the presence of Pd(acac)2, tri(2-furyl)phosphine, and NaH in tetrahydrofuran at 40 °C to provide para-C-H bond aminated products in satisfactory to high yields with acceptable regioselectivity in most cases. The electronic property of the substituents linked to the benzene rings did not significantly influence the reactivity of the 2-aryl chloromethylbenzene substrates and the reaction regioselectivity.

Spirocarbocycle Synthesis from Chloromethylarenes via Transition-Metal-Catalyzed Allylative Dearomatization and Ring Closure Metathesis.

A strategy for the synthesis of spirocarbocycles by using chloromethyl arenes as starting materials is described in this paper. The palladium-catalyzed allylative dearomatization and the subsequent ruthenium-catalyzed ring closure metathesis proceeded smoothly under mild conditions to produce the corresponding spirocarbocycle products with moderate to high yields. Benzene-ring-, naphthalene-ring-, and anthracene-ring-containing substrates can be easily transformed into spirocarbocycles by using the proposed method.

Hydrogenation of nitriles to primary amines catalyzed by an unsupported nanoporous palladium catalyst: understanding the essential reason for the high activity and selectivity of the catalyst.

An efficient and highly selective heterogeneous catalyst system for nitrile hydrogenation was developed using unsupported palladium nanopores (PdNPore). The PdNPore-catalyzed selective hydrogenation of nitriles proceeded smoothly, without any additives, under mild conditions (low H2 pressure and low temperature) to yield primary amines with satisfactory to excellent yields. Systematic studies demonstrated that the high activity and excellent selectivity of the PdNPore originated from its good Lewis acidity and porous structure. No palladium leached from the PdNPore during the hydrogenation reaction. Moreover, the catalyst was easily recovered and reused without any loss of catalytic activity. A deuterium-hydrogen exchange reaction clearly indicated that the present hydrogenation involves heterolytic H2 splitting on the surface of the PdNPore catalyst.

Palladium-Catalyzed Cycloisomerization of 2-Ethynylbiaryls to 9-Methylidene Fluorenes.

A palladium-catalyzed cycloisomerization of 2-ethynylbiaryls to 9-methylidene fluorenes is described for the first time. The cycloisomerization of 2-ethynylbiaryls proceeded smoothly in the presence of weak acid at low temperature to afford 9-methylidene fluorenes in satisfactory to high yields. This new type of cycloisomerization of 2-ethynylbiaryls is operationally simple and scalable and exhibits high functional-group tolerance. Various synthetically useful functional groups, such as halogen atoms, as well as formyl, acetyl, methoxycarbonyl, cyano, and nitro groups, remain intact during the cycloisomerization of 2-ethynylbiaryls.

Establishment of a new cell line of canine inflammatory mammary cancer: IMC-118.

Canine inflammatory mammary cancer (IMC) has long been regarded as an attractive animal model for research into human inflammatory breast cancer (IBC), Although some canine mammary tumour cell lines corresponding to human mammary cancer cell lines have been established, there is still a need to supplement the canine mammary tumour cell bank. The goal of this study was to create a new type of IMC cell line. The primary tumour, IMC-118, was identified as IMC by pathology examination. Immunohistochemistry analysis revealed negative immunoreactivity to oestrogen receptor (ER), but positive immunoreactivity to progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER-2). Immunofluorescence (IF) analysis revealed that the IMC-118 cell line from this primary tumour was negative for ER but positive for PR and HER-2, and was also positive for epithelial and mesenchymal cell markers. This cell line was cultured stably for more than 50 passages and grew well after cryopreservation. In vivo, tumour masses and metastases in the lungs were discovered after inoculating the IMC-118 cells into the nude mice model. As a result, a novel canine IMC cell line, IMC-118, was effectively established, and could be employed as a promising model for immunotherapy and epithelial-mesenchymal transition mechanism of IMC research in both dogs and humans.

Palladium-Catalyzed Tail-to-Tail Reductive Dimerization of Terminal Alkynes to 2,3-Dibranched Butadienes.

The palladium-catalyzed tail-to-tail reductive dimerization of terminal alkynes is described for the first time. Aromatic terminal alkynes bearing diverse and sensitive functional groups as well as aliphatic terminal alkynes are efficiently transformed to 2,3-dibranched butadienes. The key to achieve a selective tail-to-tail reductive dimerization reaction is to control appropriately the acidity of the reaction solution, which is accomplished by a combined use of pivalic acid and para-toluenesulfonic acid. The tail-to-tail reductive dimerization reaction is proposed to proceed via a cationic alkenyl palladium intermediate under acidic conditions.

Three-component addition of terminal alkynes, carboxylic acids, and tert-butyl hypochlorite.

This paper described the unprecedented three-component addition of terminal alkynes, carboxylic acids, and tert-butyl hypochlorite. This new type of addition proceeds smoothly to produce gem-dichloroalkane derivatives in satisfactory to excellent yields via successive two-time additions under mild conditions. The synthetically useful functional groups, such as Cl, Br, CN, and NO2, remained intact in the final products.

Chiral Indolizidine Synthesis through the Ir-Catalyzed Asymmetric Hydrogenation of Cyclic Pyridinium Salts.

The Ir-catalyzed asymmetric hydrogenation of cyclic pyridinium salts is presented as a new strategy for the convenient and efficient synthesis of chiral indolizidines. The asymmetric hydrogenation of cyclic pyridinium salts derived from 2-(2-acylphenyl)pyridines proceeded smoothly in the presence of [Ir(cod)Cl]2 and (R)-DM-SegPhos to provide the desired chiral 7,8-benzoindolizidines 6 in high to excellent yields with moderate enantioselectivity (up to 86:14 er) and excellent diastereoselectivity (>20:1 dr). The enantiomeric purity of 6j was increased to 92:8 through recrystallization.

Unsupported Nanoporous Platinum-Iron Bimetallic Catalyst for the Chemoselective Hydrogenation of Halonitrobenzenes to Haloanilines.

An unsupported nanoporous platinum-iron bimetallic catalyst (PtFeNPore) was prepared with an electrochemical dealloying technique. Its structure and composition were characterized through various measurement methods, such as X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS). An intermetallic compound and iron oxide species were both found in the PtFeNPore catalyst. The nanoporous structure and Lewis acidity (caused by iron oxide species) of the PtFeNPore catalyst resulted in superior catalytic activity and high selectivity. The PtFeNPore-catalyzed hydrogenation of various halonitrobenzenes proceeded successfully under mild reaction conditions and produced good to excellent yields of the corresponding haloanilines with high selectivity. PtFeNPore can be recycled through magnetic separation easily and reused five times without significant deactivation.

Palladium-Catalyzed Three-Component Coupling Reaction via Benzylpalladium Intermediate.

Transition-metal catalyzed multi-component reactions have captured the attention of researchers in organic synthesis and drug synthesis due to their advantages of simple operation, easy availability of raw materials and without separation of intermediates. Among the multi-component reactions, the three-component processes have been developed into effective organic procedures. This personal account reviews our and other group's studies on the development of three-component coupling reaction for the rapid construction of two new chemical bonds simultaneously via benzylpalladium intermediates. Catalyst-switched three-component reactions of benzyl halides, activated olefins, and allyltributylstannane were successfully conducted to produce the corresponding benzylallylation products. Activation and conversion of carbon monoxide and carbon dioxide via π-benzylpalladium intermediates provide access to a wide range of unsaturated ketones and esters with excellent functional group tolerance. Meanwhile, other methods to produce benzylpalladium intermediates, including Heck insertion of alkenes into arylpalladium complexes, the oxidative addition of benzyl carbonate to palladium complexes and palladium-carbene migratory insertion, were also highlighted.

A Strategy for Amide C-N Bond Activation with Ruthenium Catalyst: Selective Aromatic Acylation.

A strategy for amide C-N bond activation with ruthenium catalyst is described for the first time. The in situ formed bis-cycloruthenated complexes were demonstrated to be the key active species with superior oxidative addition ability to an inert amide C-N bond. The direct C-H bond activation of 2-arylpyridines followed by the amide C-N bond activation took place in the presence of a ruthenium precatalyst to produce monoacylation products in moderate to good yields. Synthetically useful functional groups, such as halogen atoms (F and Cl), ester, acetyl, and vinyl, remained intact during tandem C-H/C-N bond activation reactions.