Iron-Catalyzed Borylation of Propargylic Acetates for the Synthesis of Multisubstituted Allenylboronates.

A novel iron-catalyzed borylation of propargylic acetates leading to allenylboronates has been developed. The method allows the preparation of a variety of di-, tri- and tetrasubstituted allenylboronates at room temperature with good functional group compatibility. Stereochemical studies show that an anti-SN 2' displacement of acetate by boron occurs; this also allows transfer of chirality to yield enantiomerically enriched allenylboronates. The synthetic utility of this protocol was further substantiated by transformations of the obtained allenylboronates including oxidation and propargylation.

Anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord via one vertebra with two bony channels for adjacent two-segment cervical spondylotic myelopathy: a technical note.

BACKGROUND: The current treatments for adjacent two-segment cervical spondylotic myelopathy (CSM) include two-segment anterior cervical discectomy and fusion (ACDF) and single-segment anterior cervical corpectomy and fusion (ACCF). Long-term follow-up has demonstrated that both procedures have complications such as reduced cervical mobility, accelerated degeneration of adjacent segments and loosening of internal fixation screws. The purpose of this study is to demonstrate the feasibility, safety, and efficacy of anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord (APFETDSC) via one vertebra with two bony channels for the treatment of adjacent two-segment CSM and to present our surgical experience. METHODS: Anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord (APFETDSC) via one vertebra with two bony channels was performed for 12 patients with adjacent two-segment CSM with follow-up care for at least 12 months. The Visual analog scale (VAS) and the Japanese Orthopedic Association Score (JOA) were recorded, and modified Macnab criteria were used to evaluate the treatment excellence rate. Radiological examinations, including X-ray, computed tomography (CT) and magnetic resonance imaging (MRI), were used to evaluate spinal cord decompression, intervertebral stability and healing of the bony channel. RESULTS: All 12 patients completed the operation successfully. No postoperative complications, such as dysphagia, Horner's syndrome, or laryngeal recurrent nerve palsy, were found. The postoperative VAS and JOA scores were significantly improved compared with those before surgery(P < 0.001). According to the modified Macnab criteria, the clinical outcome was excellent in 8 cases, good in 3 cases and fine in 1 case at the final follow-up and the excellent and good rate was 91.7%. Postoperative and follow-up imaging showed significant spinal cord decompression, well-healed bony channels and no cervical instability. CONCLUSIONS: This study is the first report of anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord via one vertebra with two bony channels. This procedure has the advantages of less trauma, faster recovery, fewer complications and no need to implant internal fixators. This is a minimally invasive, feasible and safe surgical procedure for patients with adjacent two-segment CSM.

3D nanocake-like Au-MXene/Au pallet structure-based label-free electrochemical aptasensor for paraquat determination.

3D nanocake-like Au-MXene and Au pallet (Au-MXene/AuP) nanocomposite-modified screen-printed carbon electrodes (SPCEs) were utilized to construct an ultrasensitive label-free electrochemical aptasensor through a self-assembly procedure for trace paraquat (PQ) residue detection. Benefiting from the excellent electrochemical (EC) performances (e.g., high conductivity and large surface area) of Au-MXene nanocomposites and AuP substrate, the developed Apt/Au-MXene/AuP/SPCE-based EC aptasensor displayed excellent specificity and anti-interference ability, good repeatability, and stability. A linear relationship between the log value of the change in current intensity [lg (ΔI)] and the log value of the concentration of PQ [lg (CPQ)] was obtained in the range 0.05-1000 ng/mL. The limit of detection was 0.028 ng/mL, and the sensitivity was 255.5 µA/(µM·cm2). Practical applications in malt and mint samples confirmed the accuracy of the EC aptasensor in complex matrices for PQ detection, providing a universal analytical tool for other trace pesticides in different food samples by simply replacing the corresponding aptamers.

Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles.

Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.

Overcoming the limitations of directed C-H functionalizations of heterocycles.

In directed C-H activation reactions, any nitrogen or sulphur atoms present in heterocyclic substrates will coordinate strongly with metal catalysts. This coordination, which can lead to catalyst poisoning or C-H functionalization at an undesired position, limits the application of C-H activation reactions in heterocycle-based drug discovery, in which regard they have attracted much interest from pharmaceutical companies. Here we report a robust and synthetically useful method that overcomes the complications associated with performing C-H functionalization reactions on heterocycles. Our approach employs a simple N-methoxy amide group, which serves as both a directing group and an anionic ligand that promotes the in situ generation of the reactive PdX2 (X = ArCONOMe) species from a Pd(0) source using air as the sole oxidant. In this way, the PdX2 species is localized near the target C-H bond, avoiding interference from any nitrogen or sulphur atoms present in the heterocyclic substrates. This reaction overrides the conventional positional selectivity patterns observed with substrates containing strongly coordinating heteroatoms, including nitrogen, sulphur and phosphorus. Thus, this operationally simple aerobic reaction demonstrates that it is possible to bypass a fundamental limitation that has long plagued applications of directed C-H activation in medicinal chemistry.

Electrochemical Access to Aza-Polycyclic Aromatic Hydrocarbons: Rhoda-Electrocatalyzed Domino Alkyne Annulations.

Nitrogen-doped polycyclic aromatic hydrocarbons (aza-PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza-PAHs was developed via a rhodium-catalyzed cascade C-H activation and alkyne annulation. A multifunctional O-methylamidoxime enabled the high chemo- and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C-H activation steps. In addition, the metalla-electrocatalyzed multiple C-H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups.

Flow Rhodaelectro-Catalyzed Alkyne Annulations by Versatile C-H Activation: Mechanistic Support for Rhodium(III/IV).

A flow-metallaelectro-catalyzed C-H activation was realized in terms of robust rhodaelectro-catalyzed alkyne annulations. To this end, a modular electro-flow cell with a porous graphite felt anode was designed to ensure efficient turnover. Thereby, a variety of C-H/N-H functionalizations proved amenable for alkyne annulations with high levels of regioselectivity and functional group tolerance, viable in both an inter- or intramolecular manner. The electro-flow C-H activation allowed easy scale up, while in-operando kinetic analysis was accomplished by online flow-NMR spectroscopy. Mechanistic studies suggest an oxidatively induced reductive elimination pathway on rhodium(III) in an electrocatalytic regime.

Percutaneous full-endoscopic anterior transcorporeal cervical discectomy and channel repair: a technique note report.

BACKGROUND: Compared to anterior cervical discectomy and fusion (ACDF), cervical motion segment and disc was retained through anterior transcorporeal herniotomy (ATH). But surgical field and manipulation in traditional ATH was restricted by the narrow channel. Percutaneous full-endoscopic transdiscal cervical discectomy is a minimally invasive and functional spine surgery. However, significant loss of intervertebral disc height was inevitable. This study was done to illustrate the feasibility, safety, and efficacy and present our surgical experience of percutaneous full-endoscopic anterior transcorporeal cervical discectomy (PEATCD) and channel repair (CR) for the treatment of cervical disc herniation (CDH). METHODS: Four patients with CDH were chosen to undergo PEATCD and CR with a follow-up care for at least 22 months. The visual analogue score (VAS), Japanese Orthopedic Association (JOA), and modified Macnab criteria were recorded during the postoperative periods. CT images were obtained to observe the healing of the channel at 1 week and 3 months after the operation. RESULTS: The average operating time was 83.75 min. Drainage tubes were unnecessary. No procedure-related complications occurred. The postoperative VAS and JOA scores were improved compared to those of the preoperative assessment. The clinical efficacy was excellent in 3 patients and good in 1 patient at final follow up stage according to the modified Macnab criteria. The hernia was removed completely in all patients according to postoperative MRI. Migration of the repair implementation and collapse of the drilled vertebrae were not observed during the postoperative periods. The bony channel was nearly absent on CT images obtained at 3 months postoperative. CONCLUSION: This is the first time that the anterior transcorporeal cervical discectomy and CR have been performed simultaneously under endoscopy. Less damage to disc and the retained cervical motion segment were achieved through this method. This is a feasible, safe, and minimally invasive procedure. TRIAL REGISTRATION: Numbers: ChiCTR1800016383 . Registered 29 may 2018. Retrospectively registered. TRIAL REGISTRY: Chinese Clinical Trial Registry.

Rhodaelectrocatalysis for Annulative C-H Activation: Polycyclic Aromatic Hydrocarbons through Versatile Double Electrocatalysis.

Rapid access to structurally diversified polycyclic aromatic hydrocarbons (PAHs) in a controlled manner is of key significance in materials sciences. Herein, we describe a strategy featuring two distinct electrocatalytic C-H transformations for the synthesis of novel nonplanar PAHs. The combination of rhodaelectrooxidative C-H activation/[2+2+2] alkyne annulation of easily accessible boronic acids with electrocatalytic cyclodehydrogenation provided modular access to diversely substituted PAHs with electricity as a sustainable oxidant. The unique molecular topology as well as the photophysical and electronic properties of the thus obtained PAHs were fully analyzed. The unique power of this metallaelectrocatalysis method was demonstrated by the chemoselective assembly of synthetically useful iodo-substituted PAHs.

[Research progress of pretreatment technology for mycotoxin detection in Chinese materia medica and complex matrices].

In the processes of planting, harvest, transport and storage, improper treatment of Chinese materia medica (CMM) and foodstuffs and agricultural products will result in fungal growth and mycotoxins contamination, which will not only directly affect the quality, safety and efficacy of these complex matrices, but also seriously threaten the consumers' health and lives. Therefore, the establishment of high-throughout analytical methods with high sensitivity for the determination of mycotoxins in CMM and foodstuffs and agricultural products at trace levels will provide reliable references for reducing the risk of mycotoxin exposure in humans. Due to the matrix complexity of CMM and foodstuffs and agricultural products, highly-effective pretreatment technologies are necessary for the establishment of such analytical techniques. In this review, the current extraction and purification methods commonly used for the detection of mycotoxins were summarized, the importance of pretreatment techniques for the precise quantification of mycotoxins in complex matrices such as Chinese herbal medicines was highlighted, as well as the development tendency about the pretreatment techniques for mycotoxins in complex matrices in the future was proposed.

[Contamination distribution and control measures of aflatoxins in Chinese herbal pieces].

As an important part of traditional medicine in China, traditional Chinese medicine(TCM) plays a significant role because of its unique medical efficiency, less adverse reactions and extensive resources. However, in recent years, the aflatoxins in medicinal herbs have been detected excessive both at home and abroad, seriously affecting the reputation and credibility of traditional Chinese medicine. In this paper, the current status of aflatoxins contamination in medicinal herbs was analyzed, and the internal and external factors of aflatoxins contamination in traditional Chinese medicine were also summarized. In view of the high toxicity of aflatoxins, it is proposed to strengthen the mildew prevention and control from the early planting to storage stage, and the reasonable detoxification mode should also be considered. This review aims to provide a reference in guaranteeing the clinical safe administration of medicinal herbs and reducing the risk of being poisoned by aflatoxins.

Electrooxidative Rhodium-Catalyzed C-H/C-H Activation: Electricity as Oxidant for Cross-Dehydrogenative Alkenylation.

Rhodium(III) catalysis has enabled a plethora of oxidative C-H functionalizations, which predominantly employ stoichiometric amounts of toxic and/or expensive metal oxidants. In contrast, we herein describe the first electrochemical rhodium-catalyzed C-H activation that avoids hazardous chemical oxidants. Environmentally benign twofold C-H/C-H functionalizations were accomplished with weakly coordinating benzoic acids and benzamides, employing electricity as the terminal oxidant and generating H2 as the sole byproduct.

[Research progresses and formulation development of natural anti-mildew agents based on Chinese herbal medicines].

Owing to the intrinsic factors and some extrinsic environmental conditions, many foods, agricultural products and Chinese materia medicas (CMMs), if not handled properly in the processes of growth, harvesting, processing and storage, can be easily contaminated by all kinds of molds to produce mycotoxins of serious toxicity, which will not only affect the quality, safety and effectiveness of CMMs, but also result in potential threatens to human and animal's health and life. Therefore, in recent decades, it has become the focus on how to prevent and control the foods, agricultural products and CMMs from being moldy and producing toxicity for scientific preservation. Many Chinese herbal medicines (CHMs) especially those with high content of volatile oils with strong antifungal activities have been applied for the scientific preservation of foods, agricultural products and CMMs. Based on these situations, natural anti-mildew agents have been further developed and made into some useful dosage forms, such as tablets, aerosol, liposomes and inclusion, which will not only greatly expand the application scope of CHMs to make the use of anti-mildew agents more convenient, but also achieve the sustained or controlled release of the antifungal effect for scientific preservation of foods, agricultural products and CMMs.

Pd-Catalyzed α-Selective C-H Functionalization of Olefins: En Route to 4-Imino-ß-Lactams.

Pd-catalyzed α-olefinic C-H activation of simple α,ß-unsaturated olefins has been developed. 4-imino-ß-lactam derivatives were readily synthesized via activation of α-olefinic C-H bonds with excellent cis stereoselectivity. A wide range of heterocycles at the ß-position are compatible with this reaction. The product of 4-imino-ß-lactam derivatives can be readily converted to 2-aminoquinoline which exists extensively in pharmaceutical drugs and natural products.

Simultaneous Quantification of Seven Bioactive Flavonoids in Citri Reticulatae Pericarpium by Ultra-Fast Liquid Chromatography Coupled with Tandem Mass Spectrometry.

INTRODUCTION: Citri Reticulatae Pericarpium (CRP) is a commonly-used traditional Chinese medicine with flavonoids as the major bioactive components. Nevertheless, the contents of the flavonoids in CRP of different sources may significantly vary affecting their therapeutic effects. Thus, the setting up of a reliable and comprehensive quality assessment method for flavonoids in CRP is necessary. OBJECTIVE: To set up a rapid and sensitive ultra-fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) method for simultaneous quantification of seven bioactive flavonoids in CRP. METHODS: A UFLC-MS/MS method coupled to ultrasound-assisted extraction was developed for simultaneous separation and quantification of seven flavonoids including hesperidin, neohesperidin, naringin, narirutin, tangeretin, nobiletin and sinensetin in 16 batches of CRP samples from different sources in China. RESULTS: The established method showed good linearity for all analytes with correlation coefficient (R) over 0.9980, together with satisfactory accuracy, precision and reproducibility. Furthermore, the recoveries at the three spiked levels were higher than 89.71% with relative standard deviations (RSDs) lower than 5.19%. The results indicated that the contents of seven bioactive flavonoids in CRP varied significantly among different sources. Among the samples under study, hesperidin showed the highest contents in 16 samples ranged from 27.50 to 86.30 mg/g, the contents of hesperidin in CRP-15 and CRP-9 were 27.50 and 86.30 mg/g, respectively, while, the amount of narirutin was too low to be measured in some samples. CONCLUSION: This study revealed that the developed UFLC-MS/MS method was simple, sensitive and reliable for simultaneous quantification of multi-components in CRP with potential perspective for quality control of complex matrices. Copyright © 2016 John Wiley & Sons, Ltd.

[Simultaneous determination of 11 mycotoxins in malt by isotope internal standard-UPLC-MS/MS].

A suitable ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of 11 mycotoxins with isotope internal standard in malt. The mycotoxins in malt were extracted and purified by one-step ultrasonic extraction procedure using acetonitrile/water/acetic acid (80 : 19 : 1), and then detected and confirmed by UPLC-MS/MS, and quantified by isotope labeled AFB1 ([13C17]-AFB1) and ZEN ([13C18]-ZEN) internal standards. Rapid separation of the 11 mycotoxins was successfully achieved on a Phenomenex Kinetex C18 column (100 mm x 2.1 mm, 2.6 µm) with gradient elution using the mobile phase of methanol containing 0.1% formic acid and 2 mmol x L(-1) ammonium acetate in water. Simultaneous acquisition was performed in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI) source operated in both positive and negative ionization modes. The established method provided a good linearity for the 11 mycotoxins within their respective linear ranges with correlation coefficients all higher than 0.999 1. The average recoveries ranged from 75.0% to 117.0% with relative standard deviations (RSDs) below 5.1%. The limits of detection (LODs) and quantitation (LOQs) ranged from 0.05 to 30 µg x kg(-1) and 0.15 to 87.5 µg x kg(-1), respectively, which were below the maximum residue levels (MRLs) set by the European Union. Twenty malt samples were analyzed and nine samples were detected with mycotoxins, which were confirmed according to the same fragment ions found in positive samples and the standards at the same retention time. This study has demonstrated that the one-step extraction procedure of mycotoxins from complex matrices coupled to UPLC-MS/MS method is simple, quick, accurate and sensitive for quantitative and qualitative analysis of multiple mycotoxins in malt.

[Application and prospect of "couplet medicine" techniques in preservation of Chinese medicinal materials].

Chinese medicinal materials (CMMs) are easily to be contaminated by all kinds of molds to produce various mycotoxins due to their internal factors and the external environmental conditions during the growth, harvesting, processing, and especially storage processes. This will not only affect the quality of CMMs, resulting in enormous financial loss, but also influence the safety and effectiveness of CMMs, posing potential threats to human health. With the increase in awareness of "traditional Chinese medicine health" idea, more and more attention has been paid on how to prevent and control these CMMs from being mouldy to guarantee their safety. Some physical and chemical techniques have been restricted for protecting CMMs due to their own disadvantages. As a green, safe and economic strategy for the preservation of CMMs, "couplet medicine" technique based on the principle of "protecting CMM with another CMM" has been developed: two kinds of CMMs are stored together and fight against each other to prevent mildew metamorphism, exhibiting no obvious changes in color, smell and quality. Nowadays, certain application results have been obtained for the "antagonistic storage" method based on the above mode and principle. In this paper, we would review and discuss the mechanism, practical application and the problems of "couplet medicine" technique, and provide scientific evidences for developing safe and effective tools to protect CMMs from being mouldy.

[Research progress of Chinese herbal medicine raw materials in cosmetics].

Advocating green, nature, environmental protection, safety and the pursuit of efficacy are the trends of cosmetics in the world. In recent years, more and more Chinese herbal extracts with mild, high safety and small irritation are applied to cosmetics as the natural additives. This has become a new hot spot. The recent application advances of Chinese medicine raw materials in cosmetics are overviewed according to their main functions. This review will provide useful references for the future development and application of Chinese medicinal herbs cosmetics.

[Review of scientific preservation techniques for traditional Chinese medicine becoming mouldy during storage].

All kinds of traditional Chinese medicines (TCMs) differed from each other with different chemical components and properties. Owing to poor conditions and technologies, and the lack of scientific preservation, most TCMs will easily become mouldy during the processes of growth, harvest, handling, translation and especially storage, which will not only influence the quality, safety and efficacy of TCMs, but also cause serious waste and economic losses, and even do great harm to human health. The process of storage is closely related to the qualities of TCMs with many interference factors. Therefore, scientific preservation of TCM during storage is crucial to prevent them from being mouldy. This review analyzed the important harm of mouldy TCMs, summarized the internal and external factors of resulting in TCMs to become mouldy. Based on the above discussion, together with the characteristics and limitations of current TCM preservation techniques, we prospect novel, scientific and reasonable preservation techniques, expecting to provide references for scientific preservation of TCMs to avoid becoming mouldy and guarantee their qualities.

[Application prospect and expectation of fungistatic agents of plants in preservation of Chinese herbal medicines].

During the process of growth, harvesting, transportation, processing and storage, Chinese herbal medicines (CHMs) can be easily contaminated by fungi and their metabolites like mycotoxins, which not only express negative effects on the quality and safety of CHMs and their processed products, but also pose great threats to human health. Now, some chemical synthetic fungicides have been frequently used to control the growth of fungi and accumulation of mycotoxins in the preservation of CHMs. However, the concentration and type of chemical fungicides allowed for postharvest application are restricted due to the disadvantages of their high residual toxicity, long degradation period and pollution to the environment and so on. Therefore, it is critical to research and develop some highly effective, safe and non-toxic, natural, environment-friendly fungistatic agents from plants to prevent CHMs from being contaminated by fungi and mycotoxins. The paper reviews mycotoxins and their harmfulness, the effective compounds of fungistatic plants as well as the antifungal mechanism to provide scientific evidences for developing novel and effective fungistatic agents plants. Then, the application prospect of fungistatic agents from plants in the preservation of CHMs was discussed.