1,720,963 research outputs found
Green methodologies for the synthesis and use of isocyanides and their application in medicinal chemistry
No full textThe isocyanide stands out as an intriguing entity, owing to its chameleonic reactivity that has made it a widely utilized reactant in organic synthesis, especially in multicomponent reactions (MCRs). Despite its pivotal role in the biological activity of natural compounds, isocyanides have historically been overlooked by medicinal chemists due to misconceptions about their toxicity, reactivity, and metabolic instability. Additionally, the structural complexity and limited availability of natural isocyanides have contributed to this neglect. However, our recent investigations have revealed that, under specific molecular contexts, the isocyanide group can resist human metabolism and show promise as a pharmacophoric group in medicinal chemistry. Therefore, the aim of this PhD was to systematically utilize the isocyanide as a pharmacophoric group, integrating it into chemically straightforward and expeditiously synthesized structures, with the goal of deploy them in medicinal chemistry screening campaigns, particularly within the domains of antimicrobial and oncological research. Another goal was to develop environmental friendly synthetic procedures for the synthesis and use of isocyanides
Exploiting the Different Nucleophilicity of the Isocyano Group: A Strategy for the Isocyanide Functionalization
No full textBy exploiting the different nucleophilicity of aromatic and aliphatic isocyanides, we selectively react aliphatic isocyano groups while preserving aromatic ones in Passerini and Ugi multicomponent reactions. This simple approach allows the synthesis of alpha-acyloxy carboxamides or alpha-acylamino carboxamides possessing one or two isocyanide groups, which are challenging to achieve through traditional formylation and dehydration protocols. These analogues have the potential to serve as valuable building blocks with diverse applications
Each Interruption is an Opportunity: Novel Synthetic Strategies Explored Through Interrupted Click Reactions
No full textThe particular and unique mechanism of the copper-catalyzed reaction between azides and alkynes (CuAAC) has not only allowed for the efficient synthesis of 1,2,3-trisubstituted 1,4-triazoles in excellent yields and under mild conditions, becoming the quintessential click reaction, but it has also enabled the straightforward formation of a metallocycle intermediate, the copper triazolyl. This, under suitable reaction conditions able to suppress its protonolysis, can be used either for the creation of new bicyclic triazolyl structures or for the generation of novel three or four-component reactions. The aim of this review is to rationalize and unify all these transformations, which are collectively referred to as "interrupted click reactions".The copper-catalyzed reaction between azides and alkynes, known as CuAAC, has allowed for the efficient synthesis of 1,2,3-trisubstituted 1,4-triazoles and the formation of a metallocycle intermediate. This intermediate can be used for creating new structures or generating multi-component reactions, collectively referred to as "interrupted click reactions" imag
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
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
I quaderni di scuola fra ricerca, didattica e terza missione. Riflessioni a margine in vista di una scheda catalografica.
No full textIl saggio affronta il tema della necessità di progettare una scheda catalografica per i quaderni di scuola che appartengono al patrimonio della vita scolastica e che sono annoverabili fra i beni culturali demo-etno-antropologici
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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