1,720,980 research outputs found
Introducing Deep Eutectic Solvents in Enolate Chemistry: Synthesis of 1-Arylpropan-2-ones under Aerobic Conditions
No full textAlkoxide-mediated enolization of 1-arylpropan-2-ones and their fluorinated derivatives, followed by α-functionalization with nucleophilic addition and substitution reactions, has been accomplished in the enviromentally friendly eutectic mixture choline chloride/urea, under aerobic conditions. The usefulness of this new protocol has also been exemplified through the synthesis of a small selection of building-block like molecules through Pd-catalyzed α-arylation reaction
Unexpected lateral-lithiation-induced alkylative ring opening of tetrahydrofurans in deep eutectic solvents: synthesis of functionalised primary alcohols
No full textAdvances in Deep Eutectic Solvents and Water: Applications in Metal- and Biocatalyzed Processes, in the Synthesis of APIs, and other Biologically Active Compounds
Full text linkOwing to a growing awareness towards environmental impact, the search for “greener”, safer, and cost-effective solvents able to replace petroleum-derived solvents has never been greater today. In this context, the use of environmentally responsible solvents like water and the so-called Deep Eutectic Solvents (DESs), constructed from bio-based compounds, has recently experienced important growth in several fields of sciences. This short review highlights the key features of the chemistry of water and (hydrated) DESs when applied to metal- and biocatalyzed transformations as well as to the synthesis of Active Pharmaceutical Ingredients (APIs) and other biologically relevant compounds by providing, through discussion of all relevant literature over the past five years, a comparison of the outcomes of the reactions when carried out in one or the other solvent
“The Great Beauty” of organolithium chemistry: a land still worth exploring
No full textThis Frontier highlights and analyses, from the authors’ perspective, the impact on organic synthesis of some recent contributions from the organolithium field, also discussing the opportunities that are on the horizon
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Regioselective desymmetrization of diaryltetrahydrofurans via directed ortho-lithiation: an unexpected help from green chemistry
No full textAn efficient functionalization of diaryltetrahydrofurans via a regioselective THF-directed ortho-lithiation is first described. This reaction can be successfully carried out in cyclopentyl methyl ether as a ‘‘greener’’ alternative to Et2O, with better results in terms of yield and selectivity and, surprisingly, also in protic eutectic mixtures competitively with protonolysis
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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