Synthesis of Some Biologically Active Cyclopente-Nones using New Organophosphorus Reagents

Abstract

The use of organic phosphorus and sulfur compounds in the general synthesis of biologically active functionalized cyclopentenones is presented.     

New Procedure of Kinetic Resolution of t-Butylphenylphosphine Oxide

Abstract

The title compound optically active t-butylphenylphosphine oxide 1 is widely used as a key substrat for the synthesis of other optically active derivatives such as α-hydroxyphosphine oxides, vinylphosphine oxides Till now, it has been obtained by a few rather laborious procedures¹     

Compatibility study of the acetylsalicylic acid with different solid dosage forms excipients

This study is part of a research project aimed to find and optimize methods by which drug-excipient compatibility can be reliably and quickly assessed. The objective of the present study was to evaluate the compatibility of the acetylsalicylic acid (ASA), an non-steroidal anti-inflammatory drug, with pharmaceutical excipients of common use including diluents, binders, disintegrants, lubricants and solubilising agents. In order to investigate the possible interactions between ASA and eleven excipients differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry analysis completed by Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction were used for compatibility study. The DSC has proven to be, among the selected analytical techniques, the most sensitive and specific in assessing the compatibility. The samples, as physical mixtures, were prepared by mixing the analyte and excipients in a proportion of 1:1 (w:w). On the basis of thermal results (especially DSC), confirmed by FT-IR and X-ray analysis, a possible chemical interaction was found between the ASA with polyvinylpyrrolidone K30 (PVP) and magnesium stearate, respectively a possible physical interaction with colloidal silicon dioxide and stearic acid (Ac. St.).     

An Improved Method for Oxidation of Sulfides to Sulfoxides with Hydrogen Peroxide in Methanol

A variety of oxidative methods have been used for the preparation of sulfoxides from the corresponding sulfides². However, only few of them permit the oxidation in a selective manner. These methods involve for example sodium metaperiodate³, dichloroiodobenzene⁴ and t-butyl hypochlorite⁵ as oxidising agent. It should be noted that it is necessary to use them in equivalent amounts in respect to sulfide in order to avoid the over-oxidation or α-halogenation reaction.     

The sila-Pummerer reaction of γ-silyl substituted cycloalkanoyl sulfoxides: the first examples and a new approach to 3-substituted cycloalk-2-enones

The thermal decomposition of 3-(α-trimethylsilyl)alkyl substituted 2-(phenylsulfinyl)cycloalkanones occurs via the γ-sila-Pummerer reaction, affording 3-substituted cycloalk-2-enones and unstable trimethylsilyl benzenesulfenate as an elimination by-product. The starting γ-silyl substituted cycloalkanoyl sulfoxides were obtained through the conjugate addition reaction of nucleophilic reagents to 2-(phenylsulfinyl)cycloalk-2-enones. The tandem conjugate addition/γ-sila-Pummerer reaction investigated here provides a new route to 3-substituted cycloalk-2-enones.     

Reliability and performances of a high-purity gamma spectrometry system used for environmental measurements

Proficiency testing is among the most methods to assess the accuracy of the analytical data produced by laboratories. The results presented in this paper show the performance of the laboratory for three intercomparisons organized by Radionuclide Metrology Laboratory (RML) and by IAEA, in which SALMROM laboratory have participated in three consecutive years. The feedbacks from the final reports from RML and IAEA demonstrate the performance of the laboratory where 34 out of 39 pass all acceptance criteria of the test. The rest of five results which failed served to improve the laboratory analysis and to optimize accuracy measurements. The overall results of the proficiency tests point out the reliability and traceability of the gamma spectrometry system used for environmental measurements.     

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.     

Nucleophilic Substitution at Tetracoordinate Phosphorus. Stereochemical Course and Mechanisms of Nucleophilic Displacement Reactions at Phosphorus in Diastereomeric cis- and trans-2-Halogeno-4-methyl-1,3,2-dioxaphosphorinan-2-thiones: Experimental and DFT Studies

Geometrical cis- and trans- isomers of 2-chloro-, 2-bromo- and 2-fluoro-4-methyl-1,3,2-dioxaphosphorinan-2-thiones were obtained in a diastereoselective way by (a) sulfurization of corresponding cyclic P^III-halogenides, (b) reaction of cyclic phosphorothioic acids with phosphorus pentachloride and (c) halogen–halogen exchange at P^IV-halogenide. Their conformation and configuration at the C₄-ring carbon and phosphorus stereocentres were studied by NMR (¹H, ³¹P) methods, X-ray analysis and density functional (DFT) calculations. The stereochemistry of displacement reactions (alkaline hydrolysis, methanolysis, aminolysis) at phosphorus and its mechanism were shown to depend on the nature of halogen. Cyclic cis- and trans-isomers of chlorides and bromides react with nucleophiles (HO⁻, CH₃O⁻, Me₂NH) with inversion of configuration at phosphorus. DFT calculations provided evidence that alkaline hydrolysis of cyclic thiophosphoryl chlorides proceeds according to the S_N2-P mechanism with a single transition state according to the potential energy surface (PES) observed. The alkaline hydrolysis reaction of cis- and trans-fluorides afforded the same mixture of the corresponding cyclic thiophosphoric acids with the thermodynamically more stable major product. Similar DFT calculations revealed that substitution at phosphorus in fluorides proceeds stepwise according to the A–E mechanism with formation of a pentacoordinate intermediate since a PES with two transition states was observed.     

Selenium Alleviates the Adverse Effect of Drought in Oilseed Crops Camelina (Camelina sativa L.) and Canola (Brassica napus L.)

Drought poses a serious threat to oilseed crops by lowering yield and crop failures under prolonged spells. A multi-year field investigation was conducted to enhance the drought tolerance in four genotypes of Camelina and canola by selenium (Se) application. The principal aim of the research was to optimize the crop yield by eliciting the physio-biochemical attributes by alleviating the adverse effects of drought stress. Both crops were cultivated under control (normal irrigation) and drought stress (skipping irrigation at stages i.e., vegetative and reproductive) conditions. Four different treatments of Se viz., seed priming with Se (75 μM), foliar application of Se (7.06 μM), foliar application of Se + Seed priming with Se (7.06 μM and 75 μM, respectively) and control (without Se), were implemented at the vegetative and reproductive stages of both crops. Sodium selenite (Na₂SeO₃), an inorganic compound was used as Se sources for both seed priming and foliar application. Data regarding physiochemical, antioxidants, and yield components were recorded as response variables at crop maturity. Results indicated that WP, OP, TP, proline, TSS, TFAA, TPr, TS, total chlorophyll contents, osmoprotectant (GB, anthocyanin, TPC, and flavonoids), antioxidants (APX, SOD, POD, and CAT), and yield components (number of branches per plant, thousand seed weight, seed, and biological yields were significantly improved by foliar Se + priming Se in both crops under drought stress. Moreover, this treatment was also helpful in boosting yield attributes under irrigated (non-stress) conditions. Camelina genotypes responded better to Se application as seed priming and foliar spray than canola for both years. It has concluded that Se application (either foliar or priming) can potentially alleviate adverse effects of drought stress in camelina and canola by eliciting various physio-biochemicals attributes under drought stress. Furthermore, Se application was also helpful for crop health under irrigated condition.