Explicit group USSOR method for solving elliptic partial differential equations

This paper presents a new 4-points Explicit Group Unsymmetric Successive Overrelaxation (USSOR) iterative method to approximate the solution of the linear systems derived from the discretisation of self-adjoint elliptic partial equations. Several studies have been carried out by many researchers on the USSOR iterative method, for example, the analysis of its convergence [1], an upper bound for its error [2] and recently a special case of the USSOR, namely the SSOR method has been used to approximate the solution of augmented systems [4] and [8]. The computational behaviour of this new method and a comparison with its point version is presented

A Multiple Criteria Framework to Evaluate Bank Branch Potential Attractiveness

Remarkable progress has occurred over the years in the performance evaluation of bank branches. Even though financial measures are usually considered the most important in assessing branch viability, we posit that insufficient attention has been given to other factors that affect the branches’ potential profitability and attractiveness. Based on the integrated used of cognitive maps and MCDA techniques, we propose a framework that adds value to the way that potential attractiveness criteria to assess bank branches are selected and to the way that the trade-offs between those criteria are obtained. This framework is the result of a process involving several directors from the five largest banks operating in Portugal, and follows a constructivist approach. Our findings suggest that the use of cognitive maps systematically identifies previously omitted criteria that may assess potential attractiveness. The use of MCDA techniques may clarify and add transparency to the way trade-offs are dealt with. Advantages and disadvantages of the proposed framework are also discussed.

NMR in the epoxidation of (E,E)-Cinnamylideneacetophenones

The epoxidation of cinnamylideneacetophenones have been already performed with hydrogen peroxide as an oxidant in Julia's method [1] and with dimethyldioxirane [2], however no studies were performed using salen Mn(III) complexes as catalysts.The epoxidation of cinnatnylideneacetophenones have been already performed with hydrogen peroxide as oxidant in Julia's method [1] and with dimethyldioxirane [2], however no studies were performed using salen Mn(lll) complexes as catalysts. On these basis, we developed a study on the epoxidation of cinnamylideneacetophenones 1, catalyzed by coinmercially available Jacobsen's catalyst [salen Mn(IIl)] and using iodosy I benzene and hydrogen peroxide as oxidants. The structure of the epoxidation products 2-5, their stereochemistry and the regiochemistry of the monoepoxides 2 fotmation were established by ID and 2D NMR spectroscopy. These studies will be presented and discussed

Novel Hydroxy-9H-xanthen-9-ones derivatives: synthesis and bioactive properties

9H-Xanthen-9-ones commonly referred as xanthones are a large group of natural heterocyclic compounds with significant bioactive properties (e.g. anti-inflammatory, antibacterial, antimalarial, cytotoxicity and radical scavenging activity).1 In order to explore some of these biological assessments, we developed two methodologies for the synthesis of novel hydroxylated 2,3-diarylxanthone derivatives. The first synthetic route is based on the Heck reaction of the 3-bromochromone 2 followed by aldol condensation and electrocyclisation/oxidation processes to afford the 2,3-diaryl-9H-xanthen-9-ones 1. An efficient and more general approach is the Heck reaction of 3-bromo-2-styrylchromones 3 with styrenes as olefins followed by the in situ electrocyclisation/oxidation processes.2 Pharmacological studies involving the hydroxy-9H-xanthen-9-ones 1,3 which are obtained after cleavage of the methyl group, will also be presented and discussed

Synthesis and transformation of halochromones

Chromones (4H-1-benzopyran-4-ones) are one of the most abundant groups of naturally occurring oxygen containing heterocyclic compounds possessing a benzo-γ-pyrone framework, 1a. The significance of these widely spread and highly diverse compounds is far beyond the important biological functions they assume in nature [1, 2]. Natural and synthetic chromone derivatives have been assigned as lead structures in drug development with some already being marketed [3]. The majority of the naturally occurring chromones are 2- and 3-aryl derivatives, called flavones 1b and isoflavones 1c, respectively. However, other types of chromones have also been found in the plant kingdom, such as 3-methylchromones 1d and 2- styrylchromones 1e (Fig. 1).University of Aveiro, Fundação para a Ciência e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the QOPNA Research Unit

A 31P nuclear magnetic resonance study of phosphate levels in roots of ectomycorrhizal and nonmycorrhizal plants of Castanea sativa Mill.

31P-Nuclear Magnetic Resonance (NMR) was used to assess phosphate distribution in ectomycorrhizal and nonmycorrhizal roots of Castanea sativa Mill. as well as in the mycorrhizal fungus Pisolithus tinctorius in order to gain insight into phosphate trafficking in these systems. The fungus P. tinctorius accumulated high levels of polyphosphates during the rapid phase of growth. Mycorrhizal and nonmycorrhizal roots accumulate orthophosphate. Only mycorrhizal roots presented polyphosphates. The content in polyphosphates increased along the 3 months of mycorrhiza formation. In mycorrhizal roots of plants cultured under axenic conditions, the orthophosphate pool decreased along the culture time. In nonmycorrhizal roots the decrease in the orthophosphate content was less pronounced. The level of orthophosphate in mycorrhizal roots was significantly lower than in nonmycorrhizal ones, which indicates that this system relies upon the fungal polyphosphates as a major source of phosphate

Synthesis of 2-{2-[5(4)-aryl-2H-[1,2,3]-triazol-4(5)-yl]vinyl}chromen-4-ones

Chromones are a family of oxygen-containing heterocyclic compounds that have been shown particular relevant biological activity. In what concerns to 2-methylchromones, their reactivity is well-known and allowed to exploit many different kinds of chemical reactions. The acidic character of the 2-methyl group, due to the low electron density at C-2 caused by carbonyl group enable this class of compounds to undergo oxidation, photolysis, cycloaddition and condensation reactionsUniversity of Aveiro, Funda9ao para a Ciencia e Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the QOPNA Research Unit (project PEst-C/QUI/UI0062/2011) and the Portuguese National NMR Network. Hello Albuquerque also thanks FCT for his fellowship (SFRH/Bl/51556/2011 )

Nitromethane conjugate addition to 2-[(1E,3E)-4-arylbuta-1,3-dien-1-yl]-4Hchromen- 4-ones

Chromone are a group of oxygen-containing heterocycles, which are often associated to important biological activities.1 Chromone derivatives are also seen as interesting scaffolds to input further functionalizations,2 most of them through chemical transformations such as oxidation, condensation, Diels-Alder or conjugate addition. Conjugate addition of carbon nucleophiles to electron-deficient alkenes is one of the most important methods available for carbon–carbon bond-forming reactions. A wide range of carbon nucleophiles easily undergo conjugate addition with various substrates such as chalcones, cinnamylideneacetophenones or styrylchromones. Following previous work of our research group involving the 1,6-conjugate addition of nitromethane to (E)-2- styrylchromones,3 herein we report the first reactivity studies in the nitromethane conjugate addition to the extended unsaturated π-system of 2-[(1E,3E)-4-arylbuta-1,3-dien-1-yl]-4H-chromen-4-ones 1 (Scheme 1). The DBU catalyzed nitromethane addition reaction afforded the corresponding β-(nitromethyl)chromones 2 (1,6-conjugate addition) as major products. (E)-5'-(Nitromethyl)-3'-styryl-[1,1'-biphenyl]-2-ol 3 and 3'-aryl-2'-nitro-5'-(nitromethyl)spiro [chromane- 2,1'-cyclohexan]-4-one 4 derivatives were also isolated as minor products, which result from the addition of two nitromethane molecules, through tandem processes.info:eu-repo/semantics/publishedVersio

Synthesis and structure elucidation of novel pyrazolyl-2-pyrazolines obtained by the reaction of 3-(3-aryl-3-oxopropenyl)chromen-4-ones with phenylhydrazine

Novel 3-aryl-5-{4-[5-(2-hydroxyphenyl)-1-phenylpyrazolyl]}-2-pyrazolines 2a-g have been prepared by the treatment of 3-(3-aryl-3-oxopropenyl)chromen-4-ones 1a-g with phenylhydrazine in refluxing acetic acid. NMR studies on deuteriochloroform solutions of pyrazolyl-2-pyrazolines 2a-g at different temperatures showed that at room temperature a mixture of diastereomers are present. This diastereoselectivity arises from the combination of the pyrazoline C-4 stereocenter and two planar chiral subunits due to internal steric hindrance. The energy barriers of this steric hindrance were overcome in DMSO-d6 solutions at 60oC. The acetylation of some pyrazolyl-2-pyrazoline derivativess 2a-c,e helped to confirm the presence of the referred mixture of diastereomers

Chalcones as versatile synthons for the synthesis of 5- and 6-membered nitrogen heterocylces

Chalcones belong to the flavonoid family which constitutes one of the major classes of naturally occurring oxygen heterocyclic compounds. The alpha,beta-unsaturated carbonyl system of chalcones possesses two electrophilic reactive centers allowing them to participate in addition reactions via attack to the carbonyl group (1,2-addition) or involving the beta-carbon (1,4-conjugate addition), leading to the synthesis of promising bioactive heterocyclic compounds. The purpose of this review is to present a systematic survey of the most recent literature that uses chalcones in the synthesis of biologically active 5- and 6-membered nitrogen heterocycles such as pyrroles, indoles, isoxazoles, imidazoles, pyrazoles, indazoles, triazoles, tetrazoles, pyridines and pyrimidines. Efficiency, easy-to-handle and cheap reagents, alternative heating conditions and greener protocols will be highlighted. In this review we will cover the literature since the beginning of the 21st century in more than 400 publications.PEst-C/QUI/UI0062/2013 FCOMP-01-0124-FEDER-03729