1,720,956 research outputs found
Efficient Synthesis of Spirooxindole-Fused 3-Thiazoline Derivatives by a One-Pot Asinger-Type Reaction
No full textA one-pot, three-component reaction has been developed and successfully employed for the synthesis of biologically relevant, highly functionalized spirooxindole-fused 3-thiazoline derivatives. Starting from ammonia, three mercapto carbonyl components and a series of substituted isatins, products were obtained in good yields (24 examples), by following a simple and rapid protocol. The obtained thiazolines proved to be optimal substrates for further transformations, including the three-component Ugi–Joullié reaction
Joining MCRs, Drug Discovery and Organocatalysis: Synthesis of Novel 3,3-Spirooxindoles Fused with Thiazolidines as New Potentially Bioactive Molecules
No full text2-Oxindoles, especially 3,3-disubstituted or spiro-fused derivatives, are recognized as highly relevant compounds for drug discovery. In particular, a great interest appeared towards oxindole-based thiazolidine compounds1 as antitumor agents, for the inhibition of the p53-MDM2 protein-protein interaction.
As part of our interest2 in multicomponent reactions (MCRs), we turned our attention to the almost unexplored Asinger reaction3 to form a thiazoline ring fused to the oxindole scaffold. Subsequently, this intermediate was subjected to a Joullié-Ugi 3-CR to give the target products in a highly efficient sequence. This combination of two sequential MCRs allowed us to synthesize a highly diverse library of spiro[indoline-3,2'-thiazolidin]-2-one derivatives.
Finally, to enhance our work, we are developing an asymmetric organocatalytic approach for the synthesis of Asinger intermediates.
References
1 Bertamino A.; Soprano M.; Musella S.; Rusciano M.R.; Sala M.; Vernieri E.; Di Sarno V.; Limatola A.; Carotenuto A.; Cosconati S.; Grieco P.; Novellino E.; Illario M.; Campiglia P.; Gomez-Monterrey I. J. Med. Chem., 2013, 56, 5407-5421.
2 Stucchi M.; Lesma G.; Meneghetti F.; Rainoldi G.; Sacchetti A.; Silvani A. J. Org. Chem., 2016, 81, 1877-1884.
3 Asinger F. Angew. Chem., 1956, 68, 377
Joining Drug Discovery and MCRs: New Spiro[indoline-3,2'-thiazolidin]-2-one Derivatives as Potentially Bioactive Anticancer Compounds
No full text2-Oxindoles, especially 3,3-disubstituted and spiro-fused derivatives, are widely recognized as highly relevant compounds for drug discovery. In particular, spirooxindole-fused thiazolidines have recently aroused great interest as promising anticancer agents, acting by inhibition of the p53-MDM2 protein-protein interaction.
1. As part of our interest in multicomponent reactions (MCRs) applied to the synthesis of oxindole-based compounds,2 we report a novel synthetic approach towards the title compounds based on two sequential MCRs. Starting from isatin derivatives 1, ammonia (2) and mercaptoacetaldehyde (3), spirooxindole-fused 3-thiazolines 4 were easily obtained by means of the underutilized Asinger reaction.3 Intermediates 4 were then subjected to a diastereoselective Joullié-Ugi reaction, which afforded products 7 in high yields, the diastereoisomers being readily separable by flash chromatography. Both MCRs display a broad substrate scope, allowing us to quickly generate a diverse library of compounds 7, for which R1-R4 substituents could be varied extensively.
Evaluation of the antiproliferative activity and p53-MDM2 protein-protein interaction inhibition of the entire library is currently underway, as well as docking studies to understand the binding mode of the most promising representatives of this novel class of lead compounds.
1. Bertamino A.; Soprano M.; Musella S.; Rusciano M.R.; Sala M.; Vernieri E.; Di Sarno V.; Limatola A.; Carotenuto A.; Cosconati S.; Grieco P.; Novellino E.; Illario M.; Campiglia P.; Gomez-Monterrey I. J. Med. Chem., 2013, 56, 5407-5421.
2. Stucchi M.; Lesma G.; Meneghetti F.; Rainoldi G.; Sacchetti A.; Silvani A. J. Org. Chem., 2016, 81, 1877-1884; de Graaff C., Ruijter E., Orru R., Chem. Soc. Rev., 2012, 41, 3969-4009.
3. Asinger F. Angew. Chem., 1956, 68, 377
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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