Synthesis of highly substituted 2,3-dihydro-1H-pyrrole derivatives via a tandem regioselective addition of nitrones to 1,3-enynes with subsequent rearrangement

A novel method for the synthesis of 1,3-enynes is described through oxidative cyclization of the semicarbazones of Michael adducts having potential nitrile functionality. Reaction of these 1,3-enynes with diaryl nitrones has yielded a diastereomeric mixture of highly substituted 2,3-dihydro-1H-pyrrole derivatives via a tandem regioselective addition with subsequent rearrangement.     

Facile one-pot,three-component synthesis of novel bis(heterocycles) incorporating thieno[2,3-b]thiophenes via Michael addition reaction

A synthesis of novel series of bis(2-amino-3-cyano-4H-chromene), bis(2-amino-3-cyanopyrano[3,2-c]chromene), bis(6-amino-5-cyano-1,4-dihydropyrano[2,3-c]pyrazole), and bis(2,7-diamino-3,4,6-tricyanopyrazolo[1,5-a]pyridine) derivatives linked to thieno[2,3-b]thiophene core via ether or ester linkages was reported. The formation of the target compounds presumably proceeds through a three component reaction of the appropriate bis(aldehyde) with 2 M of each of malononitrile and the corresponding active methylene compounds namely; dimedone, 4-hydroxycoumarine, 5-methyl-2,4-dihydro-3H-pyrazol-3-one, or cyanomethylpyrazole in dioxane at reflux in the presence of piperdine as a basic catalyst. The chemical structures of the new compounds were elucidated by several spectral tools.     

Synthesis and biological evaluation of some heterocyclic scaffolds based on the multifunctional N-(4-acetylphenyl)-2-chloroacetamide

The chloroacetamide derivative, 1 , was used as a versatile precursor for the synthesis of various types of N-aryl-2-(benzothiazol-2-ylthio)acetamide derivatives. The reaction of 1 with 2-mercaptobenzothiazole followed by condensation reaction of the produced sulfide with phenylhydrazine, 2-cyanoacetohydrazide, and/or thiosemicarbazide furnished the conforming condensation products, 4 , 7 , and 10 , respectively. Treatment of the phenylhydrazone product, 4 , with Vilsmeier formylation reagent (POCl₃/DMF) yielded the corresponding 4-formylpyrazole derivative, 5 . The thiosemicarbazone product, 10 , was reacted with ethyl bromoacetate to furnish the thiazolin-4-one derivative, 11 . The substitution reactions of chloroacetamide derivative, 1 , with 2-mercapto-4,6-dimethylnicotinonitrile and 6-amino-2-mercaptopyrimidin-4-ol, were explored to identify the sulfide products, 14 and 17 . Cyclization of 14 into its corresponding thieno[2,3-b]pyridine compound, 15 , was performed using sodium ethoxide. The thiosemicarbazone, 10 , and sulfide derivative, 14 , were found to be the most potent antibacterial compounds against Escherichia coli and Staphylococcus aureus, exhibiting growth inhibitory activities of 80.8% and 91.7%, respectively. Moreover, the thiosemicarbazone, 10 , displayed the most significant antioxidant activity with inhibitory activity of 82.6%, which comes close to the antioxidant activity of L-ascorbic acid.     

Synthesis of diverse novel compounds with anticipated antitumor activities starting with biphenyl chalcone

The chalcone as (E)-1-([1,1′-biphenyl]-4-yl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one ( 3 ) was reacted with various active methylene compounds via Michael addition reaction under different conditions. In one hand, chalcone 3 reacted with isatin and glycine in one pot reaction via 1,3-dipolar cycloaddition reaction. On the other hand, chalcone 3 was also reacted with different N-nucleophiles via direct addition on the carbonyl group to award cyclic and/or acyclic products. Meanwhile, the reaction of chalcone 3 with S-benzylthiuronium chloride afforded the thio-Michael addition product. Chalcone 3 and 10 novel synthesized compounds were screened against two cell lines (HepG2 and MCF-7). Among of them, thiosemicarbazone 16 , oxime 14 and pyrimidine-2(1H)-thione 19 derivatives revealed an excellent activity against both cell lines (IC₅₀ values = 6.79-12.91 μM), whereas thiosemicarbazone 16 (6.79 ± 0.5 and 7.58 ± 0.6 μM) showed the highest activity.     

Novel vic-dioxime ligands and their poly-metal complexes bearing 1,8-diamino-3,6-dioxaoctane: synthesis, characterization, spectroscopy and electrochemistry

Three novel vic-dioxime ligands containing the 1,8-diamino-3,6-dioxaoctane group, N,N′-(1,8-diamino-3,6-dioxaoctane)-p-tolylglyoxime (L¹SL¹H₄), N,N′-(1,8-diamino-3,6-dioxaoctane)-phenylglyoxime (L²SL²H₄), and N,N′-(1,8-diamino-3,6-dioxaoctane)-glyoxime (L³SL³H₄) have been prepared from 1,8-diamino-3,6-dioxaoctane with anti-p-tolylchloroglyoxime, anti-phenylchloroglyoxime or anti-monochloroglyoxime. Polynuclear complexes [M(L ^x SL ^x )] _n or [M(L ^x SL ^x )(H₂O)] _n (x = 1, 2 and 3), where M = Cu^II, Co^II, and Ni^II, have been obtained with 1:1 metal/ligand ratio. The Cu^II and Ni^II poly-metal complexes of these ligands are proposed to be square planar, while also the prepared Co^II complexes are proposed to be octahedral with two water molecules as axial ligands. The detection of H-bonding in the [Ni(L¹SL¹)] _n , [Ni(L²SL²)] _n and [M(L³SL³)(H₂O)] _n metal complexes by FT i.r. spectra revealed the square planar or octahedral [MN₄·H₂O)] _n coordination of poly-nuclear metal complexes. [MN₄] _n coordination of the [Ni(L¹SL¹)] _n and [Ni(L²SL²)] _n complexes were also determined by ¹H-n.m.r. spectroscopy. The ligands and poly-metal complexes were characterized by elemental analyses, FT-i.r., u.v.-vis., ¹H and ¹³C-n.m.r. spectra, magnetic susceptibility measurements, molar conductivity, cyclic voltammetry, and differential pulse voltammetric (DPV) techniques.     

Facile one-pot synthesis,butyrylcholinesterase and α-glucosidase inhibitory activities,structure–activity relationship,molecular docking and DNA–drug binding analysis of Meldrum’s acid derivatives

Research on Chemical Intermediates - Meldrum’s acid derivatives were facile synthesized by one-pot condensation process and characterized by NMR (1H, 13C, DEPT-90 and DEPT-135) and EI-MS. The...     

氨三乙酸、缬氨酸、亮氨酸的三元过渡金属配合物：合成和生物学应用

以氨三乙酸HNTA2-为主要配体,缬氨酸(valine)或亮氨酸(leucine)为次要配体在微酸性介质中合成了Ni(Ⅱ),Cu(Ⅱ),and Zn(Ⅱ)的三元配合物。用元素分析、热分析、FTIR,UV-Vis分光光度法,磁性测量和质谱法表征了合成的三元配合物。结果表明,三元配合物可在金属(M):氨三乙酸(HNTA)∶缬氨酸(valine)或亮氨酸(leucine)=1∶1∶1时制得,其分子结构为[M(HNTA)(valine)(H2O)2].1.5H2O and[M(HNTA)(leucine)(H2O)2].1.5H2O(其中M=Ni(Ⅱ)or Cu(Ⅱ))和H2[Zn(NTA)(valine)(H2O)]H2O。标题三元过渡金属配合物为八面体对称构型。同时研究了该三元配合物对大肠杆菌,金黄色葡萄球菌,白色念珠菌,黄曲霉菌(菌株从开罗大学理学院微分析中心获得)的抗菌活性。根据推荐的知名方法用标准的抗菌和抗真菌剂进行体外测试(in vitro)以评估我们的新制备的配合物对细菌和真菌物种的生长抑制活性。     

Hydrogen production by steam reforming of glycerol over Ni/Ce/Cu hydroxyapatite-supported catalysts

Hydroxyapatite-supported Ni-Ce-Cu catalysts were synthesised and tested to study their potential for use in the steam reforming of glycerol to produce hydrogen. The catalysts were prepared by the deposition-precipitation method with variable nickel, cerium, and copper loadings. The performance of the catalysts was evaluated in terms of hydrogen yield at 600°C in a tubular fixed-bed microreactor. All catalysts were characterised by the BET surface area, XRD, TPR, TEM, and FE-SEM techniques. The reaction time was 240 min in a fixed-bed reactor at 600°C and atmospheric pressure with a water-to-glycerol feed molar ratio of 8: 1. It was found that the Ni-Ce-Cu (3 mass %-7.5 mass %-7.5 mass %) hydroxyapatite-supported catalyst afforded the highest hydrogen yield (57.5 %), with a glycerol conversion rate of 97.3 %. The results indicate that Ni/Ce/Cu/hydroxyapatite has great potential as a catalyst for hydrogen production by steam reforming of glycerol.     

On the equivalence of acidic centers in H-beta zeolites tested by Fries rearrangement of phenyl acetate

The heterogeneously catalyzed liquid phase Fries rearrangement reaction of phenyl acetate was carried out on Beta zeolites reexchanged with different amounts of metal cations. The aim of this work was to determine the influence of the amount of Brønsted acid sites as the catalytic active centers on the conversion. Sodium and potassium ions as well as divalent calcium and zinc ions were used in the reexchange procedure. The conversion shows a linear dependency on the degree of ion reexchange following the theoretically expected values. So the results prove that the bridged hydroxyl groups are indeed the dominating active centers and that their strength seems to be independent of the degree of reexchange; consequently, their acidic strength should be identical. A special emphasis was placed on the reexchange with divalent metal ions. It was shown that one divalent ion is not able to replace two protons as is supposed to be necessary for the charge balance—so a 1:1 stoichiometry is needed to assume to explain the catalytic results.     

SERS-based sandwich immunoassay using antibody coated magnetic nanoparticles for Escherichia coli enumeration

A method combining immunomagnetic separation (IMS) and surface-enhanced Raman scattering (SERS) was developed to enumerate Escherichia coli (E. coli). Gold-coated magnetic spherical nanoparticles were prepared by immobilizing biotin-labeled anti-E. coli antibodies onto avidin-coated magnetic nanoparticles and used in the separation and concentration of the E. coli cells. Raman labels have been constructed using rod shaped gold nanoparticles coated with 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) and subsequently with a molecular recognizer. Then DTNB-labeled gold nanorods were interacted with gold-coated magnetic spherical nanoparticle-antibody-E. coli complex. The capture efficiency and calibration graphs were obtained and examined in different E. coli concentrations (10(1)-10(7) cfu mL(-1)). The correlation between the concentration of bacteria and SERS signal was found to be linear within the range of 10(1)-10(4) cfu mL(-1) (R(2) = 0.992). The limit of detection (LOD) and limit of quantification (LOQ) values of the developed method were found to be 8 and 24 cfu mL(-1), respectively. The selectivity of the developed immunoassay was examined with Enterobacter aerogenes, Enterobacter dissolvens, and Salmonella enteriditis which did not produce any significant response. The ability of the immunoassay to detect E. coli in real water samples was also investigated and the results were compared with the experimental results from plate-counting methods. There was no significant difference between the methods that were compared (p > 0.05). This method is rapid and sensitive to target organisms with a total analysis time of less than 70 min.