摘要 (
)
可视化
收藏
An efficient synthesis of hexahydropyrido[2,3-d]pyrimidinetrione derivatives is achieved via tandem Knoevenagel-Michael addition of aromatic aldehydes, methylcyanoacetate and 4(6)-aminouracil in solvent-free conditions in the presence of 10 mol% of ZrO2 nanoparticles (ZrO2 NPs) as a heterogeneous catalyst. The procedure is formed in high yields, short reaction time and an environmentally friendly specificity.
摘要 (
)
可视化
收藏
A simple and efficient method for the selective iodination of various aromatic compounds by using potassium iodide in the presence of benzyltriphenylphosphonium perchlorate, is reported. This method provides several advantages such as good selectiveity between ortho and para positions of aromatic compounds and high yields of the products.
摘要 (
)
可视化
收藏
Novel spiro[dibenzo[a, i]xanthene-14, 3'-indoline]-2', 8, 13-triones were prepared by the three-component reaction of β-naphthol, isatins, and 2-hydroxy-1, 4-naphoquinone in the presence of a catalytic amount of H4SiW12O40. This protocol provides a simple one-step procedure with the advantages of easy work-up, mild reaction conditions and environmentally benign.
摘要 (
)
可视化
收藏
One pot synthesis of amidoalkyl naphthols by reaction of aromatic aldehydes, 2-naphthol and amide/urea using nano-sulfated zirconia as a catalyst is reported. The reaction was carried out under solvent-free conditions. The method gave good yields of amidoalkyl naphthols in short reaction time. The catalyst is recycled for five consecutive times without loss of activity.
摘要 (
)
可视化
收藏
A series of some new quinoline based imidazole-5-one derivatives have been synthesized by the fusion of oxazol-5-ones, various p-substituted anilines and zeolite in pyridine. All the derivatives were subjected to an in vitro antimicrobial screening against a representative panel of bacteria and fungi and results worth further investigations.
摘要 (
)
可视化
收藏
Stereoselective approach for preparation of α-difluoromethyl α-propargylamines has been developed. 1, 2-Addition of lithium acetylides to diverse chiral difluoromethylated (S)-N-tert-butanesulfinyl ketimines by using Ti(OiPr)4 as catalyst and THF as solvent afforded N-tert-butanesulfinamides in good to excellent yields (51−93 %) and good diastereoselectivities (dr.85:15 to 93:7). The N-tert-butanesulfinyl group can be readily cleaved under mild acidic condition (4 mol/L HCl in dioxane) to provide the corresponding α-difluoromethyl α-propargylamine in excellent yields (90−95 %).
摘要 (
)
可视化
收藏
Thiazoles including five 2-arylbenzothiazoles and two 2-arylnaphthothiazoles were synthesized using a simple synthetic strategy in this work. 2-Arylbenzothiazoles and 2-arylnaphthothiazoles can be prepared by the reaction of methylaromatics with aniline or naphthylamine in the presence of elemental sulfur, respectively. All the seven thiazoles were characterized by the melting point measurement, FT-IR, 1H NMR, 13C NMR and GC-MS analysis.
摘要 (
)
可视化
收藏
An efficient and water tolerant method for the synthesis of β-haloamines is described utilizing hydrated nickel (II) halides (NiX2.nH2O X= Cl, Br, I) and aziridines as starting materials. N-Tosylaziridines reacted with NiCl2.6H2O or NiI2.6H2O giving β-chloro- or β-iodoamines in high yields (73~99 %) within a short time, but 10 mol% of n-Bu4NBr should be added in the reactions of N-tosylaziridines with NiBr2.3H2O in order to obtain the high yields of corresponding β-bromoamines. Solvent played an important role in the reactions. The proper solvent for the reaction of NiCl2.6H2O was DMF, while NiBr2.3H2O or NiI2.6H2O proceeded well in 1, 4-dioxane.
摘要 (
)
可视化
收藏
(R)-2-Chloro-1-(m-chlorophenyl)ethanol, a precursor of (R)-3-chlorostyrene oxide which is the key chiral intermediate for the preparation of several β3-adrenergic receptor agonists was prepared in 40% yield and 99% ee by the Lipozyme TL IM-catalyzed second resolution of the corresponding racemate in the presence of vinyl acetate.
摘要 (
)
可视化
收藏
Thirteen thiomorpholine-bearing compounds were designed and synthesized as dipeptidyl peptidase IV (DPP-IV) inhibitors, with natural and non-natural L-amino acids as the starting materials. Their structures were characterized by 1H NMR, 13C NMR and HR-MS. The target compounds were screened for the DPP-IV inhibition, and the preliminary SAR result was obtained. Particularly, compounds 4c, 4d and 4f with good DPP-IV inhibition in vitro were further evaluated through a mouse oral glucose tolerance test (OGTT). The preliminary result showed the potential value for further studies on those thiomorpholine-bearing compounds as DPP-IV inhibitors.
摘要 (
)
可视化
收藏
Click chemistry was applied to immobilize three kinds of alkyne-carboxylic acids onto azide-modified silica gel to prepare three novel stationary phases for weak cation exchange chromatography (WCX). The developed protocol combines the benefits of operational simplicity, exceptionally mild conditions and high surface loadings. Six kinds of standard proteins were separated completely on the novel packings. Compared with commercial WCX columns, the three kinds of novel WCX packings prepared by click chemistry approach have better resolution and selectivity. Lysozyme was purified successfully from egg white with the novel WCX column by one step. The purity was more than 97 % and a high specific activity was achieved to be 81435 U/mg. The results illustrate the potential of click chemistry for preparation stationary phase for IEC.
摘要 (
)
可视化
收藏
Cross double Mannich reaction and tandem cyclization were achieved under iodine catalyzed conditions, yielding a series of highly substituted 4-piperidones. Among the possible diastereomers, only one diastereomer was isolated, which could be ascribled to the chair-like transition state in six-membered ring, in which all of the hindered groups are located in the pseudoequatorial orientation.
摘要 (
)
可视化
收藏
Canrenone (1) was biotransformed into 11α-hydroxycanrenone (2) and a main byproduct (3) by Aspergillus ochraceus SIT34205. Compound 3 was separated and purified using silica gel column chromatography, and its structure was characterized via MS and NMR methods. These results indicated that 3 was 1β,11α-dihydroxycanrenone and the product of further hydroxylation of 2. Thus, investigating the structure and synthesis of 3 may be a promising method to improve the efficiency and purity of 2.
摘要 (
)
可视化
收藏
A new isocoumarin, tenuissimasatin (1), was isolated from metabolites from the endophytic fungus Alternaria tenuissima (Nees & T. Nees Fr.) Wiltshire which was isolated from the bark of Erythrophleum fordii Oliver, together with 11 known compounds (2−12). The structure and absolute configuration of 1 was determined by means of NMR and CD analysis. Compound 3 shows selective cytotoxic activity on human colon cancer cell HCT-8 (IC50 = 1.78 ?mol/L) by MTT test in vitro. Other compounds show no such activities (IC50 > 10 μmol/L).
摘要 (
)
可视化
收藏
Sinomenine is a clinically available drug for the treatment of rheumatoid arthritis (RA). In a continuous research aiming at discovery of sinomenine derivates with better bioactivity, a cross-coupling reaction of sinomenine and 1, 2-dihydroxybenzene catalyzed by a fungus Coriolus unicolor afforded an unique C-C cross-coupled compound 2, together with (S)-disinomenine and (R)-disinomenine. The structure of 2 was elucidated by MS and NMR spectroscopy. Compound 2 was further assayed for the inhibitory activity on IL-6 overproduction in SW982 cells and exhibited a much more potent activity on IL-6 (96 % inhibition) compared with those of (S)-disinomenine and sinomenine (17 % and 12 % inhibition, respectively).
摘要 (
)
可视化
收藏
Two new triterpenoid saponins named lonimacranthoide IV (1) and lonimacranthoide V (2) were isolated from the flower buds of Lonicera macranthoides Hand.-Mazz. (Caprifoliaceae). They have hederagenin as aglycone. Lonimacranthoide IV (1) is a rare chlorogenic acid ester acylated on the C-23 of hederagenin. Lonimacranthoide V (2) is a new sulfated triterpenoid saponin. The structures of the saponins were established by chemical and spectral methods.
摘要 (
)
可视化
收藏
The G-quadruplexes formed from G-rich strands in the telomere and oncogene-promoter regions are regarded as new promising targets in the cancer therapy. A G-quadruplex in the downstream flanking region of the signal transducer and activator of transcription 3 (STAT3) gene was explored. Its folding patterns were proposed to be 3:2:2 and 3:3:1 loop isomers by the mutation analysis by CD spectroscopy. The structures were constructed and refined by molecular modeling method.
摘要 (
)
可视化
收藏
A rapid and practical method for direct detection of lisinopril in anion exchange chromatography (AEC) has been developed with integrated pulsed amperometric detection (IPAD). Dionex AS18 (250 mm × 2 mm) and AG18 (50 mm × 2 mm) columns and 40 mmol/L NaOH solution were used for separation. Multi-step potential waveform parameters were optimized to maximize the signal-to-noise ratio(S/N). Utilizing the optimized waveform, the repeatability (intra-day) precision and intermediate (inter-day) precision were obtained with relative standard deviation (RSD) of 0.74, 0.93, respectively. The limit of quantification (LOQ) and limit of detection (LOD) were found to be 0.37, 0.12 ng/mL, respectively, with the correlation coefficient of 0.9998 over concentration range 0.01−1 µg/mL.The present method was successfully applied to the determination of lisinopril in human plasma. The recoveries of plasma sample spiked by 0.2 µg/mL, 0.8 µg/mL lisinopril were 98.31 % – 103.23 % with relative standard deviation (RSD) of 1.41 %, 0.61 %, respectively.
摘要 (
)
可视化
收藏
A reliable method for simultaneous determination of three antibiotic drugs (Levofloxacin, Gatifloxacin and Lomefloxacin) by differential pulse stripping voltammetry (DPSV) in Britton-Robinson buffer (pH=7.96) was presented. The method is based on adsorptive accumulation of the antibacterial drugs on a hanging mercury dropping electrode (HMDE), followed by the reduction of the adsorptive species by the technique of DPSV. Optimal conditions, the deposition time of 80 s, the deposition potential of −1250 mV, and the scan rate of 25 mV/s, were obtained. The linear concentration ranges of 0.010 – 0.080 ?g/mL were obtained for all these three antibiotic drugs, while the detection limits were 2.38, 3.20 and 1.60 ng/mL for Levofloxacin, Gatifloxacin and Lomefloxacin, respectively. In this work, chemometrics methods, such as classical least squares (CLS), partial least squares (PLS), principle component regression (PCR) and radial basis function-artificial neural networks (RBF-ANN), were used to quantitatively resolve the overlapping signals. It was found that PCR gave the best results with total relative prediction error (RPET) of 7.71 %. The proposed method was applied to determine these three drugs in several commercial food samples with spiked method and yielded satisfactory recoveries.
摘要 (
)
可视化
收藏
A derivative of thiazole (AAT) have been explored as a sensing material for preparation a selective Lu(III) PVC-based membrane sensor. The proposed sensor exhibits a Nernstian response over a wide concentration range from 1.0×10-6 to 1.0×10-1 mol/L of Lu(III) and the detection limit is 5.7×10-7 mol/L. The sensor response is independent of pH of the solution in the range 3.2–8.8 and possesses the advantages of fast response time (~6) and in particular, good selectivity to the lutetium ions with regard to most common metal ions, and especially all lanthanide ions.
摘要 (
)
可视化
收藏
A novel graft copolymer consisting of polyisoprene backbone and hydrophilic side chain with carbamic acid ester functional group was prepared via thiol-ene “click” reaction and alcohol-isocyanate reactions. Polyisoprene was synthesized by anionic polymerization using n-butyl lithium as initiator, and the pendant hydroxyl groups were introduced by the thiol-ene reaction of mercaptoethanol with the double bond of 1, 2-addition units of PI backbone in the presence of radical initiator azobisisobutyronitrile. Isocyanate end group capped poly(ethylene glycol) (mPEG-NCO) was grafted onto the PI backbone through alcohol-isocyanate reaction between the pendant hydroxyl groups and isocyanate group of mPEG-NCO. The structure of the graft copolymer were characterized and confirmed by means of size-exclusion chromatography, 1H NMR and FTIR spectroscopy.
摘要 (
)
可视化
收藏
Poly(lactic acid)-based ternary blends consisting of poly(lactic acid) (PLA), cellulolytic enzyme lignin (CEL), and polyolefine grafting maleic anhydride (PGMA) were prepared by extrusion blending and the mechanical properties and the morphology of the ternary blends were investigated. It was found that the mechanical properties varied with various loading of the components in the blends. Compared to neat PLA, the tensile strength and the Young’s modulus of the ternary blends were decreased, but the elongation at break and the impact strength were effectively improved. Scanning electron microscope observations revealed that the CEL plays a bridging role between PLA and PGMA, enhancing the miscibility between them and resulting in the improvement of ductility and toughness of the ternary blends. Considering the cost and performance, we obtained the optimal blend PLA/CEL/PGMA (80/20/20, w/w/w), of which the impact strength and the elongation at break were doubled as that of neat PLA, and the tensile strength remained moderate.
摘要 (
)
可视化
收藏
A pure inorganic porous framework based on the tungstoferrate [FeW12O40]5−, Fe(H2O)6H[Na6FeW12O40]2•44H2O (1) was obtained by the conventional aqueous solution method and characterized by elemental analysis, TG, FT-IR, UV-vis spectroscopy. Single-crystal X-ray diffraction analyses reveal that compound 1 crystallizes in the space group Fm-3m, which is composed of a porous inorganic framework [Na6FeW12O40]n with two kinds of pores A and B, accommodating Fe(H2O)6 units in pore A, which was observed rarely in the pure inorganic framework.
摘要 (
)
可视化
收藏
An aqueous synthetic route has been developed for the preparation of mercaptosuccinic acid (MSA)-capped CdTe quantum dots (QDs) using TeO2 as tellurium source and sodium borohydride as reductant. The size and the emission color of CdTe QDs can be tuned by varying the reflux time. The obtained QDs were characterized by photoluminescence (PL) spectroscopy, X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The results show that the CdTe QDs were of zinc-blende crystal structure in a sphere-like shape.
摘要 (
)
可视化
收藏
Carbon nanotubes(CNT) were successfully synthesized through chemical vapor deposition(CVD) method over cobalt catalysts using scrap tyre rubber as carbon source. The CNT as produced was investigated by means of X-ray diffraction, thermogravimetric analysis, scanning electron microscope, transmission electron microscopy and raman spectrum techniques. It was found that the obtained carbon material mainly existed in the form of CNTs.
摘要 (
)
可视化
收藏
12 % Acrylamide (AM) was grafted onto the surface of nanocellulose whiskers (NCW), which was self-assembled to be the chiral nematic suspension at 3 % content. The acrylamide grafted NCW (AM-g-NCW) was characterized with Fourier transform infrared spectroscopy (FTIR). The grafting ratio was measured by elemental analysis. The degrees of crystallinity of the AM-g-NCW were measured by X-ray diffraction (XRD). The liquid crystalline properties of the AM-g-NCW were investigated by the polarizing optical microscopy (POM). The AM-g-NCW was found to self-assembly to be a lyotropic state.
摘要 (
)
可视化
收藏
To enhance the cycling stability of Pt-based catalysts, the anti-corrosion property of support and the attachment of Pt with support should both get improved. For this purpose, a novel method is presented for in-situ preparing Pt/SnO2. The structure of Pt/SnO2 is characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), confirming the homogeneous deposition of Pt on SnO2. The high resolution TEM (HRTEM) shows the large interfaces between Pt and SnO2. The TEM photos recorded after accelerated durability tests with Pt/SnO2 show that the agglomeration and size increment of Pt particles is not severe, indicating the good stability of Pt/SnO2. The electrochemical active surface area (EAS) of Pt/SnO2 keep increasing during the 1000 cycles of cyclic voltametric (CV) sweeping in H2SO4, while the EAS decayed by 35 % when mixing Pt/SnO2 with carbon nanotubes(CNTs), indicating the superior anti-corrosion property of SnO2 in contrast to CNTs.
摘要 (
)
可视化
收藏
A new crown ether appended Fe(III) porphyrin complex was prepared by sulfuryl chloride appended benzo-15-crown-5 to the meso position of meso-5, 10, 15, 20-tetra(4-hydrophenyl)-porphyrin, and it was applied to catalytic oxidation of cyclohexene with molecular oxygen without reductant, showing a remarkable catalytic activity (conversion is up to 94 %) and selectivity for 2-cyclohexen-1-ol (73 %).
