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α-Aminonitriles were synthesized via a one-pot three-component condensation of aldehydes, amines, and trimethylsilyl cyanide using silica-bonded N-propylpiperazine sulfamic acid (SBPPSA) as a recyclable solid acid at room temperature. SBPPSA showed much the same efficiency when used in consecutive reaction runs.
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Preparation of biodiesel from soybean oils catalyzed by five acidic ionic liquids with three cationic functional groups was investigated. The improvement of the catalytic activities was affected by various functional groups including pyridine group, N-methylimidazole group, triethylamine group. Among them, [C4SO3Hpy]HSO4 with pyridine group showed better catalytic activity with the biodiesel yield of 94.5%, and still yielded more than 90% after six successive uses. The possible mechanism was also discussed by two reaction paths in detail.
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A novel egg-shell Pd-S catalyst with palladium metal as the core and a membrane of palladium sulfide as the surface has been prepared by sulphidizing Pd/C with H2S. This catalyst is effctive for the reductive alkylation of p-amino diphenylamine (PADPA) and methylisobutyl ketone (MIBK) to afford N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenedianine (DBPPD) with conversion up to 99.42 % and selectivity to 97.46 %. Comparing with the other common palladium sulfide catalysts, the membrane of palladium sulfide on the surface and the core of palladium metal cause the Pd on the surface of the new catalyst in a lower sulfur coordination, which improves its activity. Our result indicates that this new egg-shell Pd-S/C is an efficient hydrogenation catalyst.
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A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate. Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z-selectivity. A free radical mechanism has been proposed to account for the formation of the products.
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A Cu(I)-catalyzed one-pot tandem reaction of 2-bromobenzyl bromides with 1,3-dicarbonyl compounds leading to 4H-chromene derivatives has been developed. This new approach toward 4H-chromenes combines several reactions in one pot and builds molecular complexity from readily available starting materials.
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To improve the therapeutic effect of rhaponticin (RHA), a folate receptor (FR) targeted RHA prodrug was designed and regioselectively synthesized by utilizing a hydrophilic peptide spacer linked to folic acid (FA) via a releasable disulfide linker. A series of biological evaluation was investigated in vitro and in vivo. The positive results of biological investigations warrants further preclinical study before this novel targeted chemotherapeutic is considered for clinical investigation.
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The linear trienes were obtained in high yields by copper-mediated cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclo- pentadienes with dimethyl acetylenedicarboxylate (DMAD) which can be quantitatively converted to novel asymmetric hexasubstituted cyclohexadienes with high (E)-stereoselectivity. The structure of cyclohexadienes was determined via X-ray analysis.
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Novel farnesylthiosalicylic acid (FTA) derivatives 5a−m with different substituted 1,3,4-thiadiazoles were synthesized. Compounds 5b, 5c, 5e and 5f displayed anti-tumor activities superior to FTA in most cancer cells tested. Furthermore, 5e induced tumor cell apoptosis, which was accompanied by lower Bcl-2 expression, but with higher Bax and caspase 3 expression activities in cancer cells.
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A one-pot, three-component condensation reaction of an aldehyde, benzoyl acetonitrile (3-oxo-3-phenylpropane nitrile) and 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione or 3-methyl-1-phenyl-1H-pyrazol-5-amine in water to give fused pyrido[2,3- d]pyrimidines and pyrazolo[3,4-b]pyridines in high yields without any catalyst, is described.
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We have demonstrated the direct substitution of 9H-xanthen-9-ol with different nucleophilic reagents such as thiazoles, triazoles, tetrazoles, hydrazines and hydrazinecarboxamides in good to high yields. This reaction catalyzed by ferric hydrogensulfate as a heterogeneous acid catalyst in ethanol through SN1 type reaction of pyrylium with a nucleophilic reagent afforded the heterocycle- and aromatic- N-substituted xanthene derivatives as simple marked molecules in short reaction times.
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A new isopimarane-type diterpene (liwariverol, 1) and eight known compounds were isolated and characterized from the EtOAc extract of the whole plant of Potamogeton crispus. The structure of 1 was elucidated to be 17-hydroxy-8αH- isopimara-9(11),15-diene by means of spectroscopic methods. Among the isolates, crenulatoside A (2), an acyclic sesquiterpene glycoside, was found to have anti-oxidative activity with enhancement of the expression of the NAD(P)H: Quinone oxidoreductase 1 (NQO1) in human neuroblastoma SH-SY5Y cells at 100 µmol/L after a 24-hour incubation.
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A novel peptide designated secapin-1, was purified and characterized from Apis mellifera. The molecular weight of 25 amino acid peptide secapin-1 was found to be 2821.5625 Da by ESI-FTICR-MS. It showed high identity to secapin. The sequence of secapin-1 was determined to be YIINVPPRCPPGSKFVKNKCRVIVP by automatic Edman degradation. A disulfide bond was formed between Cys9 and Cys20 residues. In addition, an analogue of secapin-1 was synthesized by solid phase peptide synthesis method. The synthesis product was successfully purified and identified to homogeneity by using a combination of SEC, IEC, and RP-HPLC techniques.
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A new sesquiterpenoid, 1β,5α-guaiane-4β,10α-diol-6-one (1), was isolated from 70% EtOH extract of the rhizomes of Acorus calamus. The structure was determined on spectroscopic methods, especially 2D NMR techniques. The absolute configuration of 1 was confirmed by TDDFT quantum chemical calculation of its ECD spectrum. Compound 1 showed promising anti-diabetic activity on a insulin-mediated glucose consumption model of HepG2 cells.
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Two new copper(I) halide complexes bearing 2-(2-benzimidazolyl)-6-methylpyridine (Hbmp) and PPh3 ligands, Cu(Hbmp)(PPh3)X (X = Br (1); I (2)), have been synthesized and characterized. Single-crystal X-ray structure analysis reveals that the halide ligand has a significant impact on the Cu–Npyridyl bond lengths. Complexes 1 and 2 show the solid-state emissions at ambient temperature, varying with the halide bound to the {Cu(Hbmp)(PPh3)} motif, which are perhaps best attributed to the metal-to-ligand charge-transfer (Cu(I) → Hbmp) transition mixed with some ligand-to-ligand charge-transfer (X and PPh3 → Hbmp) character.
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Phase behavior of normal decane-dodecane (n-C10H22−C12H26, C10-C12) system confined in SBA-15 (Santa Barbara Amorphous, pore diameters 3.8, 7.8, and 17.2 nm) has been studied by using differential scanning calorimetry. It has been found solid?liquid phase diagram of the C10-C12/SBA-15 system is composed of a straight line (3.8 nm), a curve (7.8 nm) and a loop line (17.2 nm). The growth of the phase diagram clearly shows the size effect on phase behavior of binary alkanes. Phase behavior has been compared among the systems C10H22-C12H26/SBA-15, C12H26-C14H30/SBA-15 and C14H30-C16H34/SBA-15.
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Detection for deoxyribozyme (DNAzyme) cleavage usually needs complex and time-consuming radial labeling, gel electrophoresis and autoradiography. A new approach was reported for detection DNAzyme cleavage product based on molecular beacon (MB). Part of the loop of MB was designed to complementary to DNAzyme cleavage product. MB was employed to monitor ligation process of RNA/DNA complex and to convert directly cleavage product information into fluorescence signal. Detection limit of the assay is 0.02 nmol/L. The cleavage product of 8−17 DNAzyme against HCV-RNA was detected perfectly based on this assay. The method is fast, simple and ultrasensitive, which might hold great promise in DNAzyme reaction and DNAzyme gene therapy.
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In this work, the structures of a pair of isomers were identified. And we showed the ability of the selective 1D version, performed the most common NMR experiments including the 1D-HMBC and GOESY experiments, to determine the isomeric composition that were found in the production process of roflumilast. The experimental results proved that this method would be even more time saving and could get more reliable results.
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In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and fourier transform-ion cyclotron resonance mass spectrometry (HPLC-UV/FTICRMS) method was described for the investigation of impurity profile in Moxifloxacin (MOX) drug substance and chemical reference substance. Ten impurities were detected by HPLC-UV, while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules. In addition, to our knowledge, five impurities were founded for the first time in MOX drug substance.
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Sorption of Am(III) on Na-bentonite as a function of contact time, pH, ionic strength, humic acid (HA) and temperature was investigated under ambient conditions. The results showed that the sorption was strongly dependent on pH and ionic strength. Am(III) sorption can be described well by pseudo-second-order model. The presence of HA takes a positive effect at low pH; but a negative influence under high pH range. Enthalpy, entropy and Gibbs free energy (i.e., ΔH0, ΔS0 and ΔG0) calculated from sorption isotherms suggested that sorption process of Am(III) was spontaneous and endothermic.
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Cytotoxicity of Aβ with redox active metals in neuronal cells has been implicated in the progression of Alzheimer disease (AD). Zn7MT-3 protects cell against Aβ-Cu2+ toxicity. The roles of single domain proteins (α/β) and α-β domain-domain interaction of Zn7MT-3 in its anti-Aβ1-42-Cu2+ toxicity activity were investigated herein. Aβ1-42 and four mutants of human MT3 (α/β domain, β (MT3)-α (MT1) and ?31-34) were prepared and characterized. Aβ1-42-Cu2+ induced hydroxyl radical and ROS production with/without Zn-MTs were measured by fluorescence spectroscopy and DCFH-DA in living cells, respectively. These results indicate that the two domains form a co-operative unit and each of them is indispensable in conducting its bioactivity.
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(-)-(3R, 4S)-3-Acetoxy-4-phenylazetidin-2-one ((-)-1) was the key intermediate for preparing optical C-13 side-chain moiety in partial synthesis of docetaxel and paclitaxel. It can be successfully prepared via enantioselective hydrolysis of racemic esters ((±)-1) catalyzed by bacterial lipases, but the current reaction evaluation method is tedious and inconvenient. Electronic circular dichroism (ECD) has been widely applied in the stereochemical study of chiral compounds. In this paper, a rapid ECD spectroscopic method has been proposed and established to detect the transformation directly. The absolute configurations of lipase-catalyzed hydrolysis products have also been confirmed by quantum-chemical calculation using time-dependent density functional theory (TDDFT) methodology.
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Helical mesoporous silica nanorods were prepared using cetyltrimethylammonium bromide and achiral alcohols as the co-structure-directing agents. They were characterized using field-emission scanning electron microscopy, transmission electron microscopy, nitrogen sorptions, and small angle X-ray diffraction. The length of the silica nanorods increases with increasing the length of the alcohols. When n-heptanol and n-octanol were used, helical mesoporous silica nanorods with lamellar mesopores on the surfaces were obtained.
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Poly(butadiene-co-styrene) copolymer/multi-walled carbon nanotubes (SB-MWNTs) nanocomposites are prepared via terminating anionically synthesized living poly(butadiene-styryl)lithium with acyl chlorides on the MWNTs, which obtained from the carboxylation and acylation of the MWNTs. Results from the characterization of the SB-MWNTs nanocomposites, including its soluble in solvent, UV-vis and TEM of the dissolved samples, TGA and SEM of nanocomposites are presented and discussed respectively. MWNTs treated by SB can be easily distributed in the SBR (styrene-butadiene rubber) matrix.
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A quantitative structure-property relationship (QSPR) study was suggested for the prediction of λmax of azo dyes. After optimization of 3D geometry of structures, different descriptors were calculated by the HyperChem and Dragon softwares. A major problem of QSPR is the high dimensionality of the descriptor space; therefore, descriptor selection is the most important step for these studies. In this paper, an ant colony optimization (ACO) algorithm was proposed to select the best descriptors.
