Studies on 2-Aminothiophenes: Synthesis,Transformations, and Biological Evaluation of Functionally-Substituted Thiophenes and Their Fused Derivatives

Abstract

Heterocyclic enamines1 reacted with ethyl acetoacetate to afford the corresponding amide derivatives2. Treatment of2 with carbon disulphide yielded the dipotassium salts3which reacted in-situ with a variety of α -haloketones to give the respective substituted thiophenes5,8, and13. The reactivity of the latter products towards various chemical reagents was studied to yield their fused thiophene derivatives7,10,12, and14, respectively. Some representative compounds were tested for antimicrobial activity.     

Efficient synthesis and molecular docking of novel antibacterial pyrimidines and their related fused heterocyclic derivatives

3-(Benzo[d][1,3]dioxol-5-yl)-1-(thiophen-2-yl)prop-2-en-1-one reacted with each of thiourea and 6-amino-2-thioxo-2,3-dihydropyrimidin-4(1H)-one to give the corresponding pyrimidine-2(1H)-thiones. Then, these compounds reacted with the appropriate hydrazonyl chlorides in dioxane in the presence of triethylamine to afford the corresponding [1,2,4]triazolo[4,3-a]pyrimidines and their related fused pyridines. Moreover, chalcone was cyclocondensed with 2-cyanothioacetamide to give pyridine-2(1H)-thione and taken as a key synthon to novel 2-(methylthio)pyridothienopyrimidin-4(3H)-one derivative. The above derivative reacted with the appropriate hydrazonyl chlorides in dioxane in the presence of triethylamine to yield the corresponding pyridothieno[3,2-d][1,2,4]triazolo[4,3-a]pyrimidines. Study of the in vitro antimicrobial activities of the newly pyrimidines were performed. Pyridothienopyrimidine 24a showed the highest inhibitory activity against all bacteria with MIC values of 3.9, 7.81, 7.81, and 15.62 μg/mL, respectively, against Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus mutans, respectively, as compared to reference drugs. Molecular docking was studied to predict of the optimized conformation of pyrimidines as active ligands against the Escherichia coli alkaline phosphatase. The structures of the hybrid molecules were elucidated by IR, Mass, ¹H NMR, and ¹³C NMR spectra as well as elemental analyses.     

Slip at the surface of a sphere translating perpendicular to a plane wall in micropolar fluid

The Stokes axisymmetrical flow caused by a sphere translating in a micropolar fluid perpendicular to a plane wall at an arbitrary position from the wall is presented using a combined analytical-numerical method. A linear slip, Basset type, boundary condition on the surface of the sphere has been used. To solve the Stokes equations for the fluid velocity field and the microrotation vector, a general solution is constructed from fundamental solutions in both cylindrical, and spherical coordinate systems. Boundary conditions are satisfied first at the plane wall by the Fourier transforms and then on the sphere surface by the collocation method. The drag acting on the sphere is evaluated with good convergence. Numerical results for the hydrodynamic drag force and wall effect with respect to the micropolarity, slip parameters and the separation distance parameter between the sphere and the wall are presented both in tabular and graphical forms. Comparisons are made between the classical fluid and micropolar fluid.      

Hyperfine magnetic field on Cd-111 in heusler alloys Co2MnZ (Z=Si,Ga, Ge,Sn)

The time differential perturbed angular correlation method has been used to measure, as a function of temperature, the hyperfine magnetic field at Cd sites in the Heusler alloys Co₂MnZ (Z=Si, Ga, Ge, Sn). The hyperfine fields, normalized to the total magnetic moment per formula unit, show an approximately linear trend toward more positive values with increasing lattice parameter.     

Determination of trace elements in Egyptian cane sugar (Deshna Factories) by neutron activation,atomic absorption spectrophotometric and inductively coupled plasma-atomic emission spectrometric analysis

Multielemental instrumental neutron activation (INAA), inductively coupled plasmaatomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses are utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P. Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth.     

A new synthesis for 1,2,4-triazolo[1,5-a]-pyridines and 1,2,4-triazolo[1,5-a]isoquinolines

Summary Condensation of cyano acid hydrazide1 with cyclopentanone in refluxing ethanolic piperidine yields hydrazone2. With mixtures of aliphatic aldehydes and different active methylene reagents,2 reacts to 1,2,4-triazolo[1,5-a]pyridines (8a–f). Compound2 also reacts with arylidenes9a–g to give triazolopyridines10a–g. Reaction of2 with aromatic aldehydes affords compounds13a–c. Diazotation of2 with aryldiazonium chloride in ethanol at 0 °C leads to the azo adducts15a–d. The thieno-1,2,4-triazolopyridine16 is obtained by reaction of8a with elementary sulfur.16 undergoes cycloaddition with -nitrostyrene, maleic anhydride, N-arylmalemide, and acrylonitrile yielding the isoquinolines21–24. All new compounds have been characterized by their IR,¹H NMR, and mass spectra.

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Ein neuer Syntheseweg für 1,2,4-Triazolo[1,5-a]pyridine und 1,2,4-Triazolo[1,5-a]isochinoline

Zusammenfassung Kondensation des Cyanohydrazids1 mit Cyclopentanon in ethanolischem Piperidin bei Rückflußtemperatur ergibt das Hydrazon2. Mit Gemischen aus aliphatischen Aldehyden und verschiedenen Verbindungen mit aktiven Methylengruppen reagiert2 zu 1,2,4-Triazolo[1,5-a]pyridinen (8a–f). Verbindung2 reagiert außerdem mit den Arylidenen9a–g zu den Triazolopyridinen10a–g. Umsetzung von2 mit aromatischen Aldehyden führt zu den Verbindungen13a–c. Diazotierung von2 mit Aryldiazoniumchloriden in Ethanol bei 0°C ergibt die Azoaddukte15a–d. Das Thieno-1,2,4-triazolylpyridin16 erhält man durch Reaktion von8a mit elementarem Schwefel.16 geht it -Nitrostyrol, Maleinsäureanhydrid, N-Arylmaleimid und Acrylnitril eine Cycloaddition zu den Isochinolinen21–24 ein. Alle neuen Verbindungen wurden durch ihre IR-,¹H-NMR- und Massenspektren charakterisiert.

     

Synthesis and mass spectral fragmentation patterns of some nitrogen heterocycles with antimicrobial activity

5-(P-tolyl)-2-[(3-bromo-4-methoxy benzylidene) hydrazino]-thiazole 3, 3-[(3-bromo-4-mehtoxy benzylidine) amino]-2-thiohydantion 5, and 4,6-disubstituted-3-[(3-bromo-4-methoxybenzyliden) amino]-2-thioxo pyrimidines 10 have been prepared via cyclization of 3-bromo-4-methoxy benzaldehyde thiosemicarbazone 2 with 4-methyl phenacyl bromide, ethyl chloroacetate, and dicarbonyl compounds in different conditions. Acetylation of 3 and 5 with acetic anhydride gave the corresponding monoacetyl derivatives 4 and 6, while the acetylation of 5 with acetic anhydride in the presence of fused sodium acetate gave diacetyl derivative 7. Condensation of compound 5 with benzaldehyde in the presence of piperidine yielded the corresponding 3-substituted-5-benzylindene 2-thiohydation 8. Acetylation of compound 8 with acetic anhydride gave the corresponding 1-acetyl-3-substituted-5-benzylidene-2-thiohydantion 9. The mass spectral fragmentation patterns of some prepared compounds are investigated in order to elucidate the structure of the synthesized nitrogen heterocycles.     

Synthesis and in vitro study of new coumarin derivatives linked to nicotinonitrile moieties as potential acetylcholinesterase inhibitors

The appropriate pyridine-2(1H)-thiones were reacted with an equivalent amount of 5-(chloromethyl)-2-hydroxybenzaldehyde in ethanol in the presence of potassium hydroxide to give the corresponding 2-hydroxybenzaldehyde derivatives in excellent yields. The latter derivatives were taken as key synthons for the preparation of the target hybrids. Therefore, 2-hydroxybenzaldehydes were reacted with benzoylglycine in acetic anhydride in the presence of fused sodium acetate at 100°C for 6 hours to afford a new series of nicotinonitrile-coumarin hybrids. The in vitro acetylcholinesterase inhibitory activities were estimated for the new coumarins. The results were expressed as the inhibition percentage of the tested hybrids at concentration of 25 nM, compared to donepezil as a reference (inhibition percentage of 70.5). Coumarin hybrids linked to 6-(4-nitrophenyl) or 6-(4-chlorophenyl)-4-phenylnicotinonitrile exhibited more effective inhibitory activities than donepezil with inhibition percentages of 94.1 and 72.3, respectively. The new coumarins were tested for their free radical-scavenging capabilities against DPPH. Furthermore, some new coumarins were tested for in vitro cytotoxic activity against each MCF-10A, MCF-7, Caco2, and HEPG2. The new hybrids showed cytotoxicity in micromolar range (IC₅₀ of 3.5-13.9 μM) against all tested cell lines. These results clearly demonstrated that the hybrids being tested are not cytotoxic at the concentration required to inhibit acetylcholinesterase effectively.     

Ion-exchange chromatography using citrate buffer,EDTA and α-HIBA for improving the separation of no-carrier-added <Superscript>139</Superscript>Ce from La<Subscript>2</Subscript>O<Subscript>3</Subscript> target irradiated with 14.5 MeV protons

The adsorption behaviour of La/Ce system on Dowex 50W-X8 in different media, namely, nitric acid, acetate buffer and citrate buffer was studied as a function of the concentration of nitric acid and buffer pH. In addition, in cation-exchange column chromatography experiments, three different eluants, namely, citrate buffer of pH 5.5, 0.1 M EDTA and 0.2 M α-HIBA, were employed for separation of Ce(III) from La(III). The optimum conditions for improvement of radiochemical separation of no-carrier-added ¹³⁹Ce from proton irradiated lanthanum were applied using the most suitable chelating agent 0.2 M α-HIBA. The purification of ¹³⁹Ce from macro amount of La(III) was done using two columns in a sequence. The target was prepared by pressing. The production of high radionuclidic and chemical purity ¹³⁹Ce via irradiation of lanthanum oxide target at MGC-20 cyclotron of proton energy 14.5 MeV was described. The experimental yield was found to be 200 kBq/μA h.