Sharif Digital Repository

A combination of solid acids, including Oxone®, HIO3, H 5IO6, and polystyrenesulfonic acid and sodium nitrite, in the presence of wet SiO2 were used as an effective oxidizing agents for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in good to excellent yields  

Hantzsch 1, 4-dihydropyridines (1,4-DHPs) can be oxidized to the corresponding pyridine derivatives by thallium triacetate in high yields  

Reaction of the zwitterions generated from isoquinoline or pyridine and dialkyl acetylenedicarboxylate with tetronic acid leads to 1,2- dihydroisoquinoline or 1,2-dihydropyridine tetronic acid derivatives without using any catalyst or activation at room temperature  

In this work, a calixarene based ionic liquid was successfully prepared and characterized by different techniques. This ionic liquid was used as an efficient catalyst for the synthesis of a series of polysubstituted pyridines from aldehydes, malononitrile, 1,3-diketones and arylamines in water as a green solvent. Also, for the first time, symmetric and unsymmetric polysubstituted bis-pyridines were obtained in high yields from diamines using this catalyst. Mild reaction conditions, high to excellent yields, easy work-up, excellent activity and reusability of the catalyst are the key features of this method which make it an interesting and novel alternative for the synthesis of the above... 

The interaction energies of 3,5 di-methyl pyridine (A) and 2,4 di-methyl pyridine (B) on the (100) surface of body-centered cubic (bcc) iron were determined via a cluster model and ab initio quantum chemical calculations at density functional theory level. The obtained energies were used to compare the inhibition behavior of these molecules for iron corrosion in hydrochloric acid solution. The iron surface and its adsorption sites (on-top, bridge, hollow) were considered as some clusters taken from two-layered 〈100〉 planes, i.e. Fe1(1), Fe4(2,2), and Fe5(4,1). So, the process for which quantum chemical calculations was carried out consists of adsorption of molecule A (B) on these clusters.... 

The transfer of pyridinium ion across the water/nitrobenzene interface has been studied by the methods of cyclic voltammetry and ac-impedance measurements. The diffusion coefficients of these species in both media, Dw,pyH+ = 4.4 × 10-5 and DNB,pyH+ = 2.16 × 10-5 cm2 s-1, as well as the diffusion coefficient of pyridine in the organic phase, DNB,py, 3.05 × 10-7 cm2 s-1, have been calculated. The standard potential of pyridinium ion transfer, and the corresponding free energy change and its distribution coefficient between the two phases, have been reported by means of cyclic voltammetry. Impedance measurements resulted in an arc in Nyquist diagrams representing the transfer of pyridinium ion... 

Four metal dithiocarbamate complexes (Zn, Ni, Hg and Sn) based on an amine containing pyridyl and nitrile groups, 3-((pyridin-2-yl)methylamino)propanenitrile, were prepared and characterized by their elemental analysis, spectroscopic data (such as IR, 1H and 13C NMR), TGA analysis and X-ray crystallography of the Ni(II) complex. The presence of a band in the 1000 cm-1 region in the IR spectra, without any splitting, confirms the symmetrical bidentate bonding mode of the dithiocarbamate ligand. Also, the short thioureide C=N distance in the X-ray analysis of the Ni complex confirms the delocalization of π electrons over the S2CN moiety and strong double bond character between the carbon and... 

The molecular behavior of some pyridine derivatives as corrosion inhibitors of iron and aluminum in acid media, were studied quantum electrochemically. The calculations were made for three conditions; isolated inhibitor molecule, metal cluster, and finally polarized continuum media. It is concluded that for aluminum the vertical adsorption through nitrogen atom is prevailing, while for iron both vertical and planar adsorptions (through π electrons of aromatic ring) are possible, but the vertical is predominant. The inhibitor chemical potential (μ) and the extent of charge transfer (ΔN) to the metal were determined. A linear correlation between each of these and the inhibition efficiencies... 

The electrophoretic mobilities of 31 isomeric alkyl- and alkenylpyridines in capillary electrophoresis were predicted using an artificial neural network (ANN). The multiple linear regression (MLR) technique was used to select the descriptors as inputs for the artificial neural network. The neural network is a fully connected back-propagation model with a 3-6-1 architecture. The results obtained using the neural network were compared with those obtained using the MLR technique. Standard error of training and standard error of prediction were 6.28 and 5.11%, respectively, for the MLR model and 1.03 and 1.20%, respectively, for the ANN model. Two geometric parameters and one electronic... 

The 2,6-bis(diphenylphosphino)pyridine/palladium catalytic system successfully catalyzes the Heck coupling reaction of less reactive aryl chlorides as well as aryl bromides with styrene to give the corresponding olefins in reasonable yields. TBAB (tetrabutylammoniumbromide) as an additive was found to be essential for these reactions. The results of Heck reaction exhibited a high selectivity (>99/1) favoring the trans product  

In the present work a pH responsive drug nanocarrier based on magnetic mesoporous silica nanoparticles (MMSN) and polyethylene glycol-co-polyvinyl pyridine (PEG-co-PVP) was prepared. The core-shell nanocarrier was formed due to electrostatic interaction between protonated polyvinyl pyridine and surface modified MMSN with carboxylate groups. This carrier was used for pH-controllable doxorubicin release. The maximum release was occurred at pH 5.5 (pH of endosomes). This carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-Vis spectrophotometer, scanning electron microscope, and high-resolution transmission electron microscope techniques. Also the... 

In this work, the inhibitory activity of pyridine N-oxide derivatives against human severe acute respiratory syndrome (SARS) is predicted in terms of quantitative structure-activity relationship (QSAR) models. These models were developed with the aid of multivariate adaptive regression spline (MARS) and adaptive neuro-fuzzy inference system (ANFIS) combined with shuffling cross-validation technique. A shuffling MARS algorithm is utilized to select the most important variables in QSAR modeling and then these variables were used as inputs of ANFIS to predict SARS inhibitory activities of pyridine N-oxide derivatives. A data set of 119 drug-like compounds was coded with over hundred calculated... 

Indole-2(3H)thiones were cyclized under the action of 2-fluorobenzoyl chlorides to give thiochromeno[2,3-b]indol-11(6H)-ones or under the action of 2-chloronicotinoyl chlorides to give pyrido[3′,2′:5,6]thiopyrano[2, 3-b]indol-5(10H)-ones. The reaction of cyclization proceeds regioselectively in DMF and does not require transition metals for completion. Obtained heterocycles are isosteric analogues of various tetracyclic indole derived alkaloids  

An efficient, highly chemoselective and simple synthesis of secondary amines via reductive amination of aldehydes, aromatic amines and inexpensive and easily accessible Diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate (DHP) in the presence of catalytic amounts of p-toluenesulfonic acid (PTSA) in water in good to excellent yields is reported  

The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts  

Conformational diseases have been investigated extensively in recent years; as a result, a number of drug candidates have been introduced as amyloid inhibitors; however, no effective therapies have been put forward. RS-0406 with pyridazine as its core chemical structure has so far shown promising results in inhibiting amyloid formation. In the present work, using molecular dynamics, we undertook the investigation of RS-0406 interactions with U-shaped Aβ1−42 and Aβ1−40 pentamers, Aβ1−42 monomers, and double-horseshoe-like Aβ1−42. To set better parameters for the small molecule, experimental and computational log P values were obtained. In addition, an analogue of RS-0406 was also simulated... 

C14H11ClN2O, triclinic P1̄ (no. 2), a = 9.380(2) Å, b = 17.238(4) Å, c = 17.735(5) A&ring, α = 118.456(4)°, β = 98.935(5)°, γ = 92.811(5)°, V = 2465.5 Å3, Z = 8, Rgt(F) = 0.104, wRref(F 2) = 0.205, T = 200 K. © by Oldenbourg Wissenschaftsverlag