Quantitative structure-activity relationship analysis of β-amyloid aggregation inhibitors

Inhibiting the aggregation process of the β-amyloid peptide is a promising strategy in treating Alzheimer’s disease. In this work, we have collected a dataset of 80 small molecules with known inhibition levels and utilized them to develop two comprehensive quantitative structure–activity relationship models: a Bayesian model and a decision tree model. These models have exhibited high predictive accuracy: 87% of the training and test sets using the Bayesian model and 89 and 93% of the training and test sets, respectively, by the decision tree model. Subsequently these models were used to predict the activities of several new potential β-amyloid aggregation inhibitors and these predictions were indeed validated by in vitro experiments. Key chemical features correlated with the inhibition ability were identified. These include the electro-topological state of carbonyl groups, AlogP and the number of hydrogen bond donor groups. The results demonstrate the feasibility of the developed models as tools for rapid screening, which could help in the design of novel potential drug candidates for Alzheimer’s disease.     

Synthesis of 9-substituted tetrahydrodiazepinopurines: studies toward the total synthesis of asmarines

A methodology for the preparation of asmarine analogues has been developed. The asmarines are cytotoxic marine alkaloids with a unique tetrahydro[1,4]diazepino[1,2,3-g,h]purine (THDAP) structure. Three cyclization methods were applied for the preparation of the 9,9-disubstituted 10-hydroxy-THDAP system, namely, aminomercurization, iodocyclization, and acid-catalyzed cyclization. The DMPM group of the NOH functionality and cyanoethyl group of the N-9 atom were found to be the most suitable protecting groups. The structures of all compounds were mainly determined from NMR measurements including (15)N chemical shifts obtained from (15)NH HMBC spectra. The end products are at least about 1 order of magnitude less active than the natural product asmarine B.     

One-pot synthesis of thiazole-2-imine derivatives by CoFe2O4@SiO2-PA-CC-Guanidine-SA MNPs as an efficient and recyclable catalyst

A novel and atom-economic protocol for the synthesis of thiazole-2-imine derivatives was developed. Synthesis of thiazole-2-imine derivatives from primary amines, phenyl isothiocyanate and phenacyl bromide derivatives by the CoFe₂O₄@SiO₂-PA-CC-Guanidine-SA magnetic nanocatalyst in excellent yields was reported. This nanocatalyst is easily separated from the reaction mixture and can be reused for several times. For the characterization of the catalyst used of Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating-sample magnetometry (VSM) techniques.     

Chemoselective Oxidation of Benzylic Alcohols and Hydroquinones with bis-(2,4,6-Trimethylpyridinium) Dichromate (BTMPDC) as an Efficient and New Oxidizing Agent

A simple, efficient, and chemoselective oxidation of benzylic alcohols to the corresponding aldehydes and ketones and also hydroquinones to the benzoquinones using bis-(2,4,6-trimethylpyridinium) dichromate (BTMPDC) in acetonitrile is described. A good range of primary and secondary benzylic alcohols and a limited range of hydroquinones were selectively oxidized under reflux conditions in reasonable yields.     

Synthesis of new tripodal Hantzsch 1,4-dihydropyridines under solvent-free condition and their conversion to the corresponding tripodal pyridines

A mixture of β-ketoester and tri-aldehydes in the presence of ammonium fluoride was converted to their corresponding tripodal 1,4-dihydropyridines under solvent-free condition with good yields. The obtained tripodal 1,4-dihydropyridines were also aromatized with oxone^®/NaNO₂/wet SiO₂ system under mild and heterogeneous conditions quantitatively.     

Differential analysis of polarity: Polar Hamilton-Jacobi,conservation laws,and Monge Ampère equations

We develop a differential theory for the polarity transform parallel to that of the Legendre transform, which is applicable when the functions studied are “geometric convex”, namely, convex, non-negative, and vanish at the origin. This analysis establishes basic tools for dealing with this duality transform, such as the polar subdifferential map, and variational formulas. Another crucial step is identifying a new, non-trivial, sub-class of C ² functions preserved under this transform. This analysis leads to a new method for solving many new first order equations reminiscent of Hamilton–Jacobi and conservation law equations, as well as some second order equations of Monge–Ampère type. This article develops the theory of strong solutions for these equations which, due to the nonlinear nature of the polarity transform, is considerably more delicate than its counterparts involving the Legendre transform. As one application, we introduce a polar form of the homogeneous Monge–Ampère equation that gives a dynamical meaning to a new method of interpolating between convex functions and bodies. A number of other applications, e.g., to optimal transport and affine differential geometry are considered in sequels.     

A novel and easy route to 1,3,4-thiadiazine derivatives via the three-component reaction of phenylhydrazine, α-bromo aryl ketones and aryl isothiocyanates

The three-component condensation of phenylhydrazine, α-bromo aryl ketones and aryl isothiocyanates leading to 1,3,4-thiadiazine derivatives is described.     

Cathodic electrodeposition and characterization of nanostructured Y2O3 from nitrate solution. Part I: Effect of current density

Particle, plate and flaky-like nanostructures of Y(OH)₃ and Y₂O₃ were prepared via cathodic electrodeposition from nitrate bath by applying different current densities. In the first step, yttrium hydroxide precursors were cathodically grown on the cathode surface at the current densities of 2, 1, 0.5, 0.25 and 0.1 mA cm^?2. The obtained hydroxide powders were heat-treated at 600°C for 3 h. The products were characterized by means of carbon, hydrogen and nitrogen (CHN), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectroscopy. From the CHN, XRD and TG results, the mechanism of base electro generation at the applied conditions and the intercalation of nitrate ions in the deposit structure were proposed and confirmed. The results showed that the structural and morphological properties of the products are directly determined by the applied current density and it can be recognized as a main factor affecting in the cathodic electrodeposition of Y₂O₃.     

Microwave Assisted Amine Formylation by a Heterogeneous HCO2H/SiO2 System

A simple, fast and efficient procedure has been developed for the synthesis of formamides by treating a silica gel/formic acid mixture with amines under microwave irradiation.     

Synthesis and mass spectral fragmentations of new spiro heterocycles

The reaction of dichlorodiphenoxymethane (2) with ortho-functionlized benzoic acids 1a-c yielded the spiro derivatives of bezodioxinone 4a, benzoxazinone 4b and benzodioxepinone 4c. The same reaction with 1,8-diaminonaphthalene afforded the spiro perimidine 6, while with 1,1'-binaphthy1-2,2'-diol gave the semi-cyclized derivative 2,2-diphenoxydinaphthodioxepine 8.