Synthesis of Some New Heterocycles of Pharmaceutical Interest: Pyridinyl and Isoxazolyl Quinoxaline Derivatives

3‐(p‐Acetyl‐anilinomethyl)quinoxalin‐2(1H)‐one ( 3 ) was prepared by the reaction of 3‐bromomethyl‐quinoxalin‐2(1H)‐one ( 1 ) with p‐aminoacetophenone ( 2 ) in pyridine. Reaction of p‐acetylcompound ( 3 ) with aromatic aldehydes yield the corresponding chalcones ( 4a‐c ). Condensation of latter chalcones with malononitrile afforded cyanopyridines ( 5a‐c ). Also, the reaction of chalcones ( 4a‐c ) with hydroxylamine hydrochloride furnished isoxazoles ( 6a‐c ). The reaction of bromo compound ( 1 ) with p‐aminobenzophenone yield ( 8 ) which was condenced with hydrazine hydrate to get the corresponding hydrazone derivatives ( 9 ). Some of the synthesized compounds have been screened for their antimicrobial activity against various strains of bacteria and fungi.     

Synthesis of Certain S-Triazole and s-Triazolo[3,4-B] 1,3,4-Thiadiazole Derivatives of Expected Pharmacological Activity

Reaction of the newly prepared 3-(2-thienyl)-4-amino-s-triazole-5-thione (I) with different alkyl kalides and aromatic aldehydes afforded the corresponding thioethers and arylidene derivatives (II and III), respectively. Attempt ring closure of (I) with acetic anhydride produced the unexpected triacetyl derivative (IV). The synthesis of certain 3-(2-thienyl)-6-substituted-s-triazolo[3,4-b] 1,3,4-thiadiazoles (V and VII) was described. IR, NMR and mass spectral analyses of the prepared compounds were discussed.     

Cyanoacetamide in heterocyclic chemistry: Synthesis,antitumor and antioxidant activities of some new benzothiophenes

Cyanoacylation of 2‐amino‐tetrahydrobenzothiophene‐3‐carboxylate ethyl ester with 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐3‐oxopropanenitrile afforded cyanoacetamide 2 . The later was utilized as key intermediate for the synthesis of 3‐substituted 2‐iminocoumarins 3 , 4 , 5 , 6 and acrylamides 7a , b via Knoevenagel condensation with 2‐hydroxy‐1‐naphthaldehyde; 2‐hydroxybenzaldehyde; 1‐nitrosonaphthalen‐2‐ol; 7‐hydroxy‐5‐methoxy‐2‐methyl‐4‐oxo‐4H‐chromene‐6‐carbaldehyde; 4‐dimethylamino‐benzaldehyde; and 4‐piperidin‐1‐yl‐benzaldehyde in EtOH/piperidine. The derivatives 7a , b did not afford the pyrazoles 8a , b upon treating with phenyl hydrazine. Furthermore, coupling of 2 with 4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one and 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine afforded the hydrazone derivatives 9 and 10 , respectively. The later derivative 10 was cyclized in acetic acid to afford the pyridopyrazolotriazine 11 . Finally, 2 was treated with dimethylformamide‐dimethylacetal (DMF‐DMA) to afford the dimethylaminoacrylamide 12 which underwent transamination with 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine to afford the pyrazole 13 . Cyclization of compound 13 in acetic acid or pyridine was unsuccessful. The antitumor and antioxidant activities of the synthesized products were evaluated; several were found to exhibit promising antioxidant activities. J. Heterocyclic Chem., (2011).     

Threshold switching in V2O5-ZnO-SrO-FeO glasses

Density and current–field characteristics related to switching phenomenon in zinc-doped strontium iron vanadate glasses having the formula (70 ? x)%V₂O₅–x%ZnO–10%SrO–20%FeO, have been investigated over a wide composition range [0 ≤ x ≤ 15] at different thicknesses and temperatures. The samples are found to show threshold switching behavior. The switching fields are found to increase with the increase of zinc content while they decrease when the temperature is increased. The activation energy for switching was found to increase with the increase of ZnO content. Finally, the switching results are discussed in terms of the electrothermal model depending on the samples thicknesses and power calculus.     

Synthesis and Spectroscopic Studies of 3-(3 N-Arylidenehydrazino-1,2,4-triazol-5-yl)-coumarins and Their Biological Activities

The electronic absorption spectra of 3-(3 N-arylidenehydrazino-1,2,4-triazol-5-yl) coumarin III are investigated in organic solvents of varying polarities and buffer solutions of different PH. The behaviour of the latter is utilized in calculating pka values of these compounds. The important bands in the IR spectra and the main ¹H NMR signals are assigned and discussed in relation to molecular structure. The antimicrobial activity of these compound has been investigated.     

Spectrophotometric Studies and Analytical Applications of the Complexes of Fe(III), Ni(II) and Cu(II) with Some 4-Amino-Antipyrene Azo Derivatives

Extensive study of composition, stability constants and optimum conditions of Fe(III), Nl (II) and Cu(II) complexes with four azo compounds based on 4 - amlnoantlpyrene are done. The coloured complexes formed, at the optimum. conditions mentioned, can be successfully used In the mlcrodetermlnation of metal Ions In synthetic solutions as well as In Incoloy 800 alloy. The method described Is rapid, sensitive, highly accurate and reproducable.     

On the Feasibility of an In Vitro Noninvasive Absorbance-Based Cell Proliferation Analysis Technique,Using Cell Culture Media

The preliminary results of a study on the applicability of using spectrophotometry of the culture medium toward understanding of cells' response to different environments is reported. The cells are cultivated on polydimethylsiloxane (PDMS) substrates and physicochemically manipulated by varying the substrate stiffness and the dose of surface plasma treatment. By growing cervical cancer (HeLa) cells on PDMS with varying stiffness and plasma treatment levels, we tested the hypothesis that the influence of substrate stiffness and treatment can be detected through the spectrophotometry of a microvolume of cell culture medium. The results imply an opportunity of using the spectrophotometry of culture media with an integrated minimal sample retention system as a practical and noninvasive alternative to traditional bioassays requiring cells detachment.     

Tunneling Across an Inhomogeneous Delta-Barrier

The authors deal with the tunneling of electrons across an inhomogeneous delta-barrier defined by the potential energy (where 0$$ " align="middle" border="0"> and 0$$ " align="middle" border="0"> are two constants). In particular, the perpendicular incidence of an electron with a given value of the wave vector is considered. The electron is forward-scattered into the region behind the barrier (region 2: 0$$ " align="middle" border="0"> ), i. e. the wave function is composed of plane waves with all wave vectors such that and \left. 0 \right)} $$ " align="middle" border="0"> ) (where ). Therefore, if 0$$ " align="middle" border="0"> , the wave function of the electron is represented as , where . An approximate formula is derived for the amplitude . The authors pay a special attention to the flow density and calculate this function in two cases: 1. for the plane and 2. for high values of is the diffraction angle). The authors discuss the relevance of their diffraction problem in a prospective quantum-mechanical theory of the tunneling of electrons across a randomly inhomogeneous Schottky barrier.     

Induced Einstein-Hilbert-Yang-Mills action from quantum effects in generalized Kaluza-Klein theory

It is shown how the Einstein-Hilbert-Yang-Mills action may be induced from quantized matter fields on a non-abelian Kaluza-Klein background. General formulae are derived in the case of a quantized scalar field when the extra dimensions form a coset space. Explicit results are obtained in the special case of odd-dimensional spheres.