Rapid Screening of 34 Emerging Contaminants in Surface Water by UHPLC-Q-TOF-MS.

OBJECTIVES: To establish a rapid screening method for 34 emerging contaminants in surface water by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF-MS). METHODS: The pretreatment conditions of solid phase extraction (SPE) were optimized by orthogonal experimental design and the surface water samples were concentrated and extracted by Oasis® HLB and Oasis® MCX SPE columns in series. The extracts were separated by Kinetex® EVO C18 column, with gradient elution of 0.1% formic acid aqueous solution and 0.1% formic acid methanol solution. Q-TOF-MS 'fullscan' and 'targeted MS/MS' modes were used to detect 34 emerging contaminants and to establish a database with 34 emerging contaminants precursor ion, product ion and retention times. RESULTS: The 34 emerging contaminants exhibited good linearity in the concentration range respectively and the correlation coefficients (r) were higher than 0.97. The limit of detection was 0.2-10 ng/L and the recoveries were 81.2%-119.2%. The intra-day precision was 0.78%-18.70%. The method was applied to analyze multiple surface water samples and 6 emerging contaminants were detected, with a concentration range of 1.93-157.71 ng/L. CONCLUSIONS: The method is simple and rapid for screening various emerging contaminants at the trace level in surface water.

Photoinduced Arylation of Acridinium Salts: Tunable Photoredox Catalysts for C-O Bond Cleavage.

A photoinduced arylation of N-substituted acridinium salts has been developed and has exhibited a high functional group tolerance (e.g., halogen, nitrile, ketone, ester, and nitro). A broad range of well-decorated C9-arylated acridinium-based catalysts with fine-tuned photophysical and photochemical properties, namely, excited-state lifetimes and redox potentials have been synthetized in a one-step procedure. These functionalized acridinium salts were later evaluated in the photoredox-catalyzed fragmentation of 1,2-diol derivatives (lignin models). Among them, 2-bromophenyl substituted N-methyl acridinium has outperformed all photoredox catalysts, including commercial Fukuzumi's catalyst, for the selective CßO-Ar bond cleavage of diol monoarylethers to afford 1,2-diols in good yields.

Catalytic Enantioselective Functionalizations of C-H Bonds by Chiral Iridium Complexes.

The development of catalytic enantioselective transformations, enabling the construction of complex molecular scaffolds from simple precursors, has been a long-standing challenge in organic synthesis. Recent achievements in transition-metal catalyzed enantioselective functionalizations of carbon-hydrogen (C-H) bonds represent a promising pathway toward this goal. Over the last two decades, iridium catalysis has evolved as a valuable tool enabling the stereocontrolled synthesis of chiral molecules via C-H activation. The development of iridium-based systems with various chiral ligand classes, as well as studies of their reaction mechanisms, has resulted in dynamic progress in this area. This review aims to present a comprehensive picture of the enantioselective functionalizations of C-H bonds by chiral iridium complexes with emphasis on the mechanisms of the C-H activation step.

Palladium-catalyzed ortho-acyloxylation of N-nitrosoanilines via direct sp(2) C-H bond activation.

The palladium-catalyzed N-nitroso-directed ortho-acyloxylation of N-nitrosoanilines has been demonstrated via sp(2) C-H activation with a stoichiometric amount of PhI(OAc)2 as the oxidant and Ac2O/AcOH (1 : 1) or C2H5CO2H as the reaction medium. This protocol can be applied to various N-nitrosoanilines with both electron-donating and electron-withdrawing groups. In addition, the products can be further transformed to 2-(methylamino)phenols expediently by a simple reduction method.

Nickel-catalyzed direct stereoselective α-allylation of ketones with non-conjugated dienes.

The development of efficient and sustainable methods for the construction of carbon-carbon bonds with the simultaneous stereoselective generation of vicinal stereogenic centers is a longstanding goal in organic chemistry. Low-valent nickel(0) complexes which promote α-functionalization of carbonyls leveraging its pro-nucleophilic character in conjunction with suitable olefin acceptors are scarce. We report a Ni(0)NHC catalyst which selectively converts ketones and non-conjugated dienes to synthetically highly valuable α-allylated products. The catalyst directly activates the α-hydrogen atom of the carbonyl substrate transferring it to the olefin acceptor. The transformation creates adjacent quaternary and tertiary stereogenic centers in a highly diastereoselective and enantioselective manner. Computational studies indicate the ability of the Ni(0)NHC catalyst to trigger a ligand-to-ligand hydrogen transfer process from the ketone α-hydrogen atom to the olefin substrate, setting the selectivity of the process. The shown selective functionalization of the α-C-H bond of carbonyl groups by the Ni(0)NHC catalyst opens up new opportunities to exploit sustainable 3d-metal catalysis for a stereoselective access to valuable chiral building blocks.

Identification of FCER1G as a key gene in multiple myeloma based on weighted gene co-expression network analysis.

PURPOSE: Although the prognosis of multiple myeloma (MM) has remarkably improved with the emerge of novel agents, it remains incurable and relapses inevitably. The molecular mechanisms of MM have not been well-studied. Herein, this study aimed to identify key genes in MM. MATERIALS AND METHODS: The GSE39754 dataset was used to screen differentially expressed genes (DEGs) and construct a co-expression network. Hub nodes were identified in the protein and protein interaction (PPI) network. Datasets GSE13591 and GSE2658 were used to validate hub genes. Moreover, function and gene set enrichment analyses were performed to elucidate the molecular pathogenesis of MM. RESULTS: In this study, 11 genes were found to be hub genes in the co-expression network, among which four genes (CD68, FCER1G, PLAUR and LCP2) were also identified as hub nodes. In the test dataset GSE13591, CD68 and FCER1G were significantly downregulated in MM. Besides, the areas under the curve (AUCs) of CD68 and FCER1G were greater than 0.8 in both the training dataset and the test dataset. Our results also confirmed that FCER1G highly expressed patients had remarkably longer survival times in MM. Function and pathway enrichment analyses suggested that hub genes were associated with epithelial mesenchymal transition, TNF-α signaling via NF-κB and inflammatory response. GSEA in our study indicated that FCER1G participated in NK cell mediated cytotoxicity and the NOD-like receptor signaling pathway. CONCLUSION: Our study identified FCER1G as a key gene in MM, providing a novel biomarker and potential molecular mechanisms of MM for further studies.

[Effect of Astragalus and Salvia's effective components and their compatibility on JAK/STAT pathway].

OBJECTIVE: To study the effect of Astragalus and Salvia's effective components and their compatibility on JAK/STAT pathway of rats' renal fibrosis. METHODS: 66 SD rats were randomly divided into 7 groups: normal group,model group,fosinopril group, salvianolic acids group, astragalus saponins group, granules compatibility of Astragalus and Salvia group, components combination of Astragalus and Salvia group. The variation of beta2-microglobulin(beta2-MG), the changes of renal pathology and JAK/STAT pathway were observed. RESULTS: The changes in renal pathology of treatment groups had different degrees of improvement; Astragalus and Salvia could reduce the urinary beta2-MG of unilateral ureteral obstruction (UUO) rat (P < 0.05), which was equal with fosinopril group. The rest of the treatment groups decreased especially fosinopril group while the difference was not significant when compared with the model group. Astragalus and its effective components could reduce the expression of renal tissue JAK, STAT1, STAT3 protein, among which fosinopril group and granules compatibility of Astragalus decreased significantly. Astragalus saponins group was not obvious, and the rest of the treatment group had significantly minor effect. CONCLUSION: Astragalus and Salvia's effective components and their compatibility may protect renal tubular function in unilateral ureteral obstruction, which may interfere with UUO rat kidney with JAK/STAT signaling pathway.

Highly stereoselective nickel-catalyzed difluoroalkylation of aryl ketones to tetrasubstituted monofluoroalkenes and quaternary alkyl difluorides.

A nickel-catalyzed difluoroalkylation of α-C-H bonds of aryl ketones to furnish highly stereo-defined tetrasubstituted monofluoroalkenes or quaternary alkyl difluorides from secondary or tertiary ketones, respectively, has been established. Mechanistic investigations indicated that these C-H fluoroalkylations proceed via a Ni(i)/Ni(iii) catalytic cycle. An obvious fluorine effect was observed in the reaction, and this reaction has demonstrated high stereoselectivity, mild conditions, and broad substrate scopes, thus enabling the late-stage fluoroalkylation of bioactive molecules. This method offers a solution for expedient construction of monofluoroalkenes from readily available materials, and provides an efficient approach for the synthesis of bioactive fluorinated compounds for the discovery of lead compounds in medicinal chemistry.

Cobalt-catalyzed difluoroalkylation of tertiary aryl ketones for facile synthesis of quaternary alkyl difluorides.

The selective incorporation of gem-difluoroalkyl groups into biologically active molecules has long been used as an efficient strategy for drug design and discovery. However, the catalytic C(sp3)-CF2 bond-forming cross-coupling reaction for selective incorporation of difluoromethylene group into diverse alkyl chains, especially more sterically demanding secondary and tertiary functionalized alkanes, still remains as a major challenge. Herein, we describe a cobalt-catalyzed difluoroalkylation of tertiary aryl ketones for facile synthesis of quaternary alkyl difluorides, which exhibited high efficiency, broad scope and mild conditions. The synthetic utility of this method is demonstrated by late-stage difluoroalkylation of donepezil, a well-known acetylcholinesterase inhibitor used to treat the Alzheimer's disease. Preliminary mechanistic investigations indicate that a difluoroalkyl radical is involved in a Co(I)/Co(III) catalytic cycle. This cobalt-catalyzed fluoroalkylation thus offers insights into an efficient way for the synthesis of fluoroalkylated bioactive molecules for drug discovery.

Nickel-Catalyzed Monofluoroalkylation of Arylsilanes via Hiyama Cross-Coupling.

The first example of nickel-catalyzed monofluoroalkylation of arylsilanes has been developed with readily available fluoroalkyl halides. This novel transformation has demonstrated high reactivity, broad substrate scope, excellent functional group tolerance, and mild reaction conditions. The selective activation of a relatively inert C-Si bond for slow release of aryl carbanion is the key reason for reducing the amount of arylmetal species, which makes this method more promising for fluorine-containing modification of complex bioactive molecules. Mechanistic investigations indicate that a free fluoroalkyl radical is involved in this catalytic cycle.

Copper-Catalyzed Decarboxylative Atom Transfer Radical Addition of Iododifluoroacetate to Alkynyl Carboxylic Acids.

The first example of copper-catalyzed decarboxylative atom transfer radical addition of alkynyl carboxylic acids has been developed with a readily available fluoroalkyl halide. This novel protocol has demonstrated a unique difunctionalization of nonterminal alkynes with a broad substrate scope and excellent functional-group tolerance. Mechanistic investigations revealed that the catalytic cycle was initiated by the attack of a difluoroalkyl radical to an in situ generated alkynylcopper species.