A Facile and Efficient Synthesis of Arylsulfonamido‐Substituted 1,5‐Benzodiazepines and N‐[2‐(3‐Benzoylthioureido)aryl]‐3‐oxobutanamide Derivatives

A facile and efficient synthesis of 1,5‐benzodiazepines with an arylsulfonamido substituent at C(3) is described. 1,5‐Benzodiazepine, derived from the condensation of benzene‐1,2‐diamine and diketene, reacts with an arylsulfonyl isocyanate via an enamine intermediate to produce the title compounds of potential synthetic and pharmacological interest in good yields (Scheme 1). In addition, reaction of benzene‐1,2‐diamine and diketene in the presence of benzoyl isothiocyanate leads to N‐[2‐(3‐benzoylthioureido)aryl]‐3‐oxobutanamide derivatives (Scheme 2). This reaction proceeds via an imine intermediate and ring opening of diazepine. The structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 3).     

Amperometric detection of ultra trace amounts of Hg(I) at the surface boron doped diamond electrode modified with iridium oxide

Iridium oxide (IrOx) films formed electrochemically on the surface boron doped diamond electrode by potential cycling in the range −0.2 to 1.2 V from a saturated solution of alkaline iridium(III) solution. A strongly adherent deposit of iridium oxide is formed after 5–10 potential scans. The properties, stability and electrochemical behavior of iridium oxide layers were investigated by atomic force microscopy and cyclic voltammetry. The boron doped diamond (BDD) electrode modified with electrodeposition of a thin film, exhibited an excellent catalytic activity for oxidation of Hg(I) over a wide pH range. The modified electrode shows excellent analytical performance for Hg(I) amperometric detection. The detection limit, sensitivity, response time and dynamic concentration ranges are 3.2 nM, 77 nA μM⁻¹, 100 ms and 5 nM–5 μM. These analytical parameters compare favorably with those obtained with modern analytical techniques and recently published electrochemical methods.     

The interaction between ketamine and some crown ethers in common organic solvents studied by NMR: the effect of donating atoms and ligand structure

1H NMR spectroscopy was used to investigate the stoichiometry and stability of the drug ketamine cation complexes with some crown ethers, such as 15-crown-5 (15C5), aza-15-crown-5 (A15C5), 18-crown-6 (18C6), aza-18-crown-6 (A18C6), diaza-18-crown-6 (DA18C6), dibenzyl-diaza-18-crown-6 (DBzDA18C6) and cryptant [2,2,2] (C222) in acetonitrile (AN), dimethylsulfoxide (DMSO) and methanol (MeOH) at 27 degrees C. In order to evaluate the formation constants of the ketamine cation complexes, the CH3 protons chemical shift (on the nitrogen atom of ketamine) was measured as function of ligand/ketamine mole ratio. The formation constant of resulting complexes were calculated by the computer fitting of chemical shift versus mole ratio data to appropriate equations. A significant chemical shift variation was not observed for 15C5 and 18C6. The stoichiometry of the mono aza and diaza ligands are 1:1 and 1:2 (ligand/ketamine), respectively. In all of the solvents studied, DA18C6 formed more stable complexes than other ligands. The solvent effect on the stability of these complexes is discussed.     

Combinatorial Algorithms for Some Variants of Inverse Obnoxious Median Location Problem on Tree Networks

This paper concerns with some variants of the inverse obnoxious median location problem on tree networks, where the aim is either to augment or to reduce the edge lengths at the minimum total cost such that a prespecified subset of vertices becomes an obnoxious multi-facility median location with respect to the perturbed edge lengths. For both augmentation and reduction models, under the rectilinear norm and the sum-type Hamming distance, we develop novel combinatorial algorithms with polynomial time complexities. Particularly, if the underlying tree is an extended star graph, then the problems can be solved in linear time.     

Selective homogeneous liquid-liquid extraction and preconcentration of copper(II) into a micro droplet using a benzo-substituted macrocyclic diamide, and its determination by electrothermal atomic absorption spectrometry

A fast and reliable method was developed for the selective separation and preconcentration of Cu²⁺ ions using homogeneous liquid-liquid extraction using a novel benzo-substituted macrocyclic diamide, 5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioatriazacyclo-pentadecine-3,11(4 H,12 H)-dione, as a selective complexing agent. An aqueous solution of Zonyl FSA (FSA) was used as a phase-separation agent at pH 4.5. Electrothermal atomic absorption spectrometry was used for Cu²⁺ determination after preconcentration. The influences of pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the ligand and the effect of diverse ions were investigated. Factorial design and response surface methods were used for the optimization purposes. Under the optimum experimental conditions, 50 ng of Cu²⁺ in 5 mL aqueous sample could be extracted quantitatively into 76 µL of the sediment phase. The maximum preconcentration factor was 65. The calibration curve was linear in the concentration range 0.2 to 4.0 µg L^?1. The detection limit and relative standard deviation were 4 ng L^?1 and 4.6%, respectively. The method was successfully applied to the extraction and determination of Cu²⁺ in natural water samples.     

Spectrophotometric determination of aqueous acidity constants of three azo dyes

The two successive steps acidity constants of three azo dye derivatives D1–D3, were determined by a spectrophotometric method using 0.10 M KNO₃ as supporting electrolyte in water solvent. The electronic spectra of the compounds were recorded in the course of their pH-metric titration with a standard base solution. The protolytic equilibrium constants can be solved very satisfactorily from absorbance data, by combining the data obtained in the spectrometric determinations with graphic methods as the absorbance diagrams. An A-diagram shows the relative absorbance changes at two wavelengths as a function of the pH. For a one-step system, the absorbance at any wavelength must be proportional to the absorbance at any other wavelength, so an A-diagram for all wavelength combinations for such a system must be linear (rank, s=1). However, if a system is governed by two or more equilibria, the A-diagrams corresponding to multi-step titrations will change direction every time a new equilibrium becomes dominant in the system. Analysis of the each uniform sub-region can then be used in evaluating of the corresponding equilibrium. A-diagrams for all wavelength combinations suggest that these systems have the rank two(s=2). The results revealed that the K_a(1) and K_a(2) values of different azo dyes follow the order D3>D2>D1.      

A practical and versatile approach toward a one-pot synthesis of 2,3-disubstituted 4(3H)-quinazolinones

Abstract  

An effective one-pot three-component route to 4(3H)-quinazolinones from commercially available starting materials is reported. Thus, isatoic anhydride reacted with ammonium acetate or primary amines and aldehydes in the presence of iodine to produce the corresponding quinazolinone derivatives in moderate to good yields.     

The odd log-logistic Topp–Leone G family of distributions: heteroscedastic regression models and applications

We introduce a new class of distributions and provide a comprehensive treatment of its mathematical properties. The maximum likelihood method is discussed to estimate the parameters of the new model by means of Monte-Carlo simulation study. The heteroscedastic regression models with long-term survival are introduced to model data sets with the non homogeneity of the error variances in the presence of cured individuals. The potentiality of the proposed models is illustrated by means of four real data sets.     

One-pot and stereoselective synthesis of 2,3-dihydro-1,5-benzodiazepin-2-one with a phosphanylidene or phosphono-succinate substituent

The one-pot synthesis of 2,3-dihydro-1,5-benzodiazepins-2-one bearing phosphanylidene (ylide) or phosphono-succinate substituent is described. In this four-component reaction, benzodiazepine derived from condensation of o-phenylenediamine and diketene is trapped with the trialkyl phosphite-dialkyl acetylenedicarboxylate zwitterion. In the presence of H₂O, the ylide functional group is hydrolyzed to the corresponding phosphonate. The configuration of the products is selective and only one of the two possible rotamers or diastereomers is formed exclusively in high yield.