Synthesis of Some [1,3]Benzodioxoles via the Reaction of o-Quinones with Phosphorus Ylides

3,5-Di(tert-butyl)benzo-1,2-quinone 1c, phenanthrene-9,10-quinone 11, and 1,2-naphthoquinone 18 react with 1-phenylethylidene(tri-phenyl)phosphorane 2j, cyclopentylidene(triphenyl)phosphorane 2k, cyclohexylidene(triphenyl)phosphorane 2l, and tetrahydro-2-furanyl-methylidene(triphenyl)phosphorane 8 to give the corresponding 2-substituted [1,3]benzodioxoles 5–7, 10, 12–14, 20–22 in low to high yields, instead of Wittig products, with exception of 11,12-dihydro-10H-cyclopenta[b]phenanthro[9,10-d]furan 17. A possible explanation for these reaction sequences is discussed.

     

Reactions Between 4-Hydroxycoumarins or 4-Hydroxy-1-Methylquinolinone and Dmad in the Presence of Phosphites. Synthesis of (Chromen-3-YL)- and (Quinolin-3-YL)-(Dialkoxyphosphoryl)Succinates

Abstract

Dimethyl (chromen-3-yl)-(dialkoxyphosphoryl)succinates are prepared from the reaction of 4-hydroxycoumarin with DMAD and P(OR)₃. 4-Hydroxy-1-methylquinolinone reacts with DMAD and P(OEt)₃ to give dimethyl (quinoline-3-yl)-(diethoxyphosphoryl)-succinate.

GRAPHICAL ABSTRACT      

Compatibility study between trandolapril and natural excipients used in solid dosage forms

Thermal analysis is an essential, analytic tool used in preliminary studies and preparation of new pharmaceutical formulations. This study was performed to investigate the possible interactions between trandolapril and three commonly used natural excipients, namely α-lactose monohydrate, microcrystalline cellulose, and pregelatinized starch. The compatibility studies were carried out using thermoanalytic along with other complementary techniques. Differential scanning calorimetry and thermogravimetric analysis have proved that trandolapril is fully compatible with all the studied excipients until 100 °C. The complementary techniques used in this study were X-ray powder diffraction, Fourier transform-infrared spectroscopy, and scanning electron microscopy which confirmed the findings of thermal analysis.     

A Novel One- and Zero-Dimensional Model for Turbulent Jet Ignition

Flow, Turbulence and Combustion - Turbulent jet ignition (TJI) is a promising combustion technology for burning highly diluted air-fuel mixtures. Computationally efficient models to assess the...     

Absolute metrology by phase and frequency modulation for multiwavelength interferometry

A fiber interferometer for absolute distance measurements is presented whereby wavelength variation is achieved via a sinusoidal strain modulation of a fiber Bragg grating to generate a series of beat wavelengths. The interferometer employs fiber laser sources where the design is based on the use of narrow-bandwidth fiber Bragg gratings. The accuracy of the beat wavelengths is improved compared to the use of multiple wavelengths measured with conventional optical spectrum analyzers or available wavemeters. Initial measurements are presented for beat wavelengths of 254.74 mm and 27.4 m over an optical path difference of 200 mm and 3.8 m, respectively. Combined with a two (or three) wavelength interferometer, this technique has the potential for ultrahigh dynamic range metrology ranging over several meters while preserving subfringe resolution and a low system complexity.     

Correlation between structure and thermal properties in 2-hydroxy-benzophenone Co(II) complexes

In this study, simultaneous TG/DTG–DTA technique was used for the simple cobalt(II) complex [Co(dpamH)₃]Br₂ (1) (dpamH = 2,2′-dipyridylamine) and the novel mixed-ligand complexes [Co(dpamH)₂(bpo)]Br (2) and [Co(dpamH)₂(opo)]Br (3), (bpo = the anion of 2-hydroxybenzophenone and opo = the anion of 2-hydroxy-4-methoxybenzophenone), in order to determine their thermal degradation in static air and dynamic nitrogen atmospheres. The cationic complexes were characterized by physicochemical methods, spectroscopy (FT-IR, UV–Vis), and single-crystal X-ray analysis, revealing octahedral coordination around cobalt(II) with chromophore CoN₄O₂, being chelated by one anionic 2-hydroxy-benzophenone ligand and two neutral dpamH molecules. The compounds crystallize as ethanol or ethanol/water solvates, with solvent molecules involved, to a different extent, in hydrogen bonding giving quite different packing modes and thus influencing their stability. The differences in crystal structures are reflected in thermal stabilities of the compounds. Thus, in the crystals of 3 ethanol is more weakly bound than in 2 and anticipate that the former one exhibit lower thermal stability, which is in agreement with the results found by TG–DTA. The thermal decomposition of the title complexes was found to be a multi-step decomposition related to the release of the solvent and ligand molecules, leading at 1,000 °C to pure metallic cobalt in nitrogen atmosphere, while in air atmosphere to the expected cobalt oxides.     

On categorical time series models with covariates

We study the problem of stationarity and ergodicity for autoregressive multinomial logistic time series models which possibly include a latent process and are defined by a GARCH-type recursive equation. We improve considerably upon the existing conditions about stationarity and ergodicity of those models. Proofs are based on theory developed for chains with complete connections. A useful coupling technique is employed for studying ergodicity of infinite order finite-state stochastic processes which generalize finite-state Markov chains. Furthermore, for the case of finite order Markov chains, we discuss ergodicity properties of a model which includes strongly exogenous but not necessarily bounded covariates.     

Spatial multicriteria decision support for robust land-use suitability: The case of landfill site selection in Northeastern Greece

Multicriteria spatial decision support systems (MC-SDSS) have emerged as an integration of geographical information systems (GIS) and multiple criteria decision aid (MCDA) methods for incorporating conflicting objectives and decision makers’ preferences into spatial decision models. In this paper, we present spatial UTASTAR (S-UTASTAR), a raster-based MC-SDSS for land-use suitability analysis. The multicriteria component of the system is based on the UTA-type disaggregation-aggregation approach. S-UTASTAR is applied in a raster-based case study concerning land-use suitability analysis to identify appropriate municipal solid waste landfill (MSW) sites in Northeast Greece. Moreover, robustness analysis tools are implemented to guarantee robust decision support results. More specifically, during the aggregation phase, the Stochastic Multiobjective Acceptability Analysis (SMAA) is used to indicate the frequency at which a site achieves the best ranking positions within a large set of alternative landfill sites.     

Length functions and Demazure operators for G(e,1,n), II

This note is the first part of consecutive two papers concerning with a length function and Demazure operators for the complex reflection group W = G(e, 1, n). In this first part, we study the word problem on W based on the work of Bremke and Malle [BM]. We show that the usual length function ?(W) associated to a given generator set S is completely described by the function n(W), introduced in [BM], associated to the root system of W.In the second part, we will study the Demazure operators of W on the symmetric algebra. We define a graded space H_W in terms of Demazure operators, and show that H_W is isomorphic to the coinvariant algebra S_W, which enables us to define a homogeneous basis on S_W parametrized by w?W.     

An infeasible (exterior point) simplex algorithm for assignment problems

The so called Modified Hung—Rom Algorithm, based upon theoretical considerations of Hirsch-paths, seems to be one of the most efficient algorithms for assignment problems. Since any two basic feasible solutions to a linear problem can always be connected with a short simplex path passing through the infeasible region, development of algorithms based upon theoretical considerations on infeasible paths seems to be of great practical interest. This paper presents an algorithm of this kind for assignment problems.