301,035 research outputs found
The Aldol Addition of 1,3-Dicarbonyl Compounds to 2-Cyanobenzaldehyde in the Synthesis of Novel 3-Substituted Isoindolinones
No full textActive methylene compounds in a very effective approach to 3-substitutedisobenzofuranones through tandem aldol/lactonization reactions
No full textIn this article we describe a new accessible methodology for the synthesis of isobenzofuran-1(3H)-ones. In
this process we exploited an effective, economic, useful and environmentally benign K2CO3 catalyzed,
solvent-free one-pot tandemaldol-lactonization reaction between activemethylene compounds andmethyl
2-carboxy benzaldehyde. A particularly simple work-up and purification procedure are additional advantages
addressed to a general green chemistry approach to this important class of heterocyclic compounds
The aldol addition of readily enolizable 1,3-dicarbonyl compounds to 2-cyanobenzaldehyde in the synthesis of novel 3-substituted isoindolinones
No full textThe aldol addition of readily enolizable 1,3-dicarbonyl compounds to 2-cyanobenzaldehyde in the presence of a tertiary amine led to a series of new 3-substituted isoindolinones. Despite the instability of the related aldols, this synthesis was possible because of the intramolecular trapping of the adducts with the cyano group due to a tandem process of cyclization-rearrangement. Simple decarboxylation of some derivatives gave access to some very useful compounds
The first organocatalytic asymmetric synthesis of 3-substituted isoindolinones
No full textHerein we describe the first asymmetric organocatalytic
synthesis of 3-substituted isoindolinones in a convenient aldolcyclization-
rearrangement tandem reaction of malonates with 2-
15 cyanobenzaldehyde. Bifunctional thiourea-cinchona catalysts proved to
be particularly effective, giving the title compounds in high yields and
moderate to good enantiomeric excesses. Moreover an efficient process of
reverse crystallization led to a further enrichment up to >99% ee
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Some Europeans are more equal than others
No full textThe position of Roma migrants in the EU presents an anomaly which challenges the foundations of European Union law. As Union citizens, European migrants are entitled to freedom of movement and residence in Member States. Yet the rights intended to secure this position have been routinely and selectively denied to Roma migrants, leading to forced evictions and collective expulsions without regard t o European Law. As has been evidenced in the UK, Roma arrivals are viewed with particularly acute suspicion; a response which reflects their double stigmatization as both immigrant and Roma. At the same time, Roma migration from new Member States has expo sed a contradiction inherent in the citizenship project which strikes at the heart of the Union ’s human rights credentials. The degree of exclusion and inequality faced by Europe’s largest minority in all Member States is the most pressing internal human rights issue facing the EU. Yet the European institutions continue to lack a coherent response and defined strategy. The current European framework demanding National Action Plans is commendable in that it prevents individual states from abdicating responsibility for the situation of their Roma citizens. Nevertheless, the absence of clear targets, Roma engagement and European leadership, suggest that this strategy is doomed to failure offering little more than a distraction. In a Union predicated on, inter alia, the rule of law, respect for human rights and the protection of minorities, this detached position undermines the legitimacy of the entire citizenship project
The design and synthesis of novel N-heterocyclic compounds, and their evaluation of anti-cancer and anti-viral activity
No full text2010 - 2011The thesis entitled “The design and synthesis of novel N-heterocyclic compounds, and their evaluation of anti-cancer and anti-viral activity" is divided into three chapters.
The title of the thesis clearly reflects the importance of nitrogen heterocycles compounds: in fact they are extremely pivotal structural motifs responsible for eliciting various biological activities in natural products and synthetic medicines. This has attracted the medicinal chemists towards the synthesis of various compounds having nitrogen heterocycles as useful medicines to treat various diseases. It is also evident by a large number of marketed pharmaceutical products possess nitrogen heterocycles. In each chapter different heterocycle moieties belonging to β-carboline, indoles and isoindolinones nucleus respectively are presented.
In the first chapter we presented β-carboline derivatives and their anticancer activity on different cell lines. Our lead compound was harmine, which is the most representative β-carboline alkaloid endowed with antitumor properties showing high cytotoxicity both in vitro against different human tumor cell lines and in vivo. It also exhibited remarkable DNA intercalation capacity and significant Topo I inhibition activity. We designed and synthesized novel β-carbolines derivatives with the aim to evaluate their antiproliferative properties, to acquire more information about the structural requirements for the possible improvement of the cytotoxic potential and to elucidate SARs between substituent properties and antitumor activities. Most of the compounds were evaluated for Topo I inhibitory activity and compaired to harmine. Almost all compounds demonstrated interesting cytotoxic activities in particular against prostate cancer cells PC-3 with IC50 in low micromolar range. Compound X was found to be the most potent one with IC50 value of 8 µM.
In the second chapter we reported the design and synthesis of new arbidol derivatives as antiviral agents: arbidol is an indole compound launched in the Russian Federation for the prophylaxis and treatment of influenza A and B and other acute respiratory viral infections, but due to its relatively high CC50 value, a clinical application is forbidden. So in order to reduce its toxicity and improve its antiviral properties, we carried out some structural modifications at position 2, 4, 5 and 6 on indole nucleus and we evaluated their effect on in vitro, anti- influenza virus (HA), hepatitis C virus (HCV) and chikungunya virus (CHIKV) activities. Viral infections are in fact the most common illnesses experienced by people of all ages and they are also one of the major causes of morbidity and mortality in elderly people and young children throughout the world. Currently, treatments are limited and the increasing prevalence of drug-resistant pathogens highlighted the need for new anti-viral drugs with novel mechanisms of action. Biological evaluation led us to discovery of a new potent influenza virus replication inhibitor, identified in compound 15. Particularly it showed activity against all the tested viruses, both A and B type; moreover it seemed to lead to a better inhibition of some viruses in comparison to Arbidol. This compound was also found to be a promising lead compound for the design of new HCV virus replication inhibitors. Actually, biological study are in course to better study mechanism underwent the action of compound 15, which could act non only as virus replication inhibitor but also as fusion inhibitor. Then a focused analysis on the interaction of this compound with the HA protein will be carried out.
The third chapter is divided into two sections.
Section A provided a brief introduction about aldol addition to 1,3-dicarbonyl compounds and described a simple and effective multicomponent regioselective one pot aldol addition/protection reaction of β-ketoesters to a series of aldehydes in the presence of Me3SiCl and i-Pr2EtN. The analysis of the scope and application of reaction revealed a dramatic dependence of the reactivity on the used substrates.
Section B described a simple and general access to a series of new phthalimidines derivatives, (mentioned in Section A) in the presence of tertiary amines under very mild conditions exploiting the aldol addition of readily enolizable 1,3 dicarbonyl compounds to 2-cyanobenzaldehyde. Recently, it has been recognized that 3-substituted isoindolinones possess a variety of biological activity, consequently, considerable effort has been devoted to the synthesis of this nitrogen heterocycle, which also act as useful synthetic building blocks and intermediates in organic synthesis.
The obtained 3-substituted isoindolinones were preliminary tested on two different virus strains (HCV and CHIKV virus) to evaluate potential activity on the virus replication, but unfortunately it was found that all compounds were not active. However further studies are desirable focusing on activities like hypnothic, anti-schizophrenia etc, for which isoindolinone moiety also shows important applications. [edited by author]X n.s
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Multi-component, regio-selective aldol addition of b-ketoesters to aldehydes: scope and applications
No full textSimple and effective multi-component one-pot aldol addition/protection reactions of b-ketoesters to a series of aldehydes in the presence Me3SiCl and i-Pr2EtN have been described. The analysis of the scope of the reaction revealed a dramatic dependence of the reactivity on the substrates used. Thus the effect of a catalytic amount of DMF and different reaction conditions was widely investigated. Further transformations of the aldol adducts were particularly useful to give valuable diols and compounds with quaternary stereocenters, while X-ray structural analysis gave also important stereochemical information about this challenging reaction
- …
