1,720,995 research outputs found
Synthesis of biologically interesting heteropolicyclic systems by palladium-catalyzed processes
No full textPalladium-catalyzed processes provide an efficient strategy for functionalization of arenes and heteroarenes with C-C and C-N bond formation and continue to offer new applications to obtain a wide range of polyfunctionalized compounds such as fused heteropolicyclic systems. The indole nucleus is the focus of the research interests but also other heterocycles such as pyrrole, furan and thiophene are examined and functionalized.
The palladium complexes exist in different oxidation states showing different reactivity. Pd(0)-complexes exhibit nucleophilic behaviour while Pd(II)-complexes react as electrophiles, thus different complexes are involved in different reaction typologies. The present thesis exploits the formation of new carbon-carbon and carbon-nitrogen bonds by using, among the known Pd-catalyzed reactions, Heck reaction, Buchwald-Hartwig reaction, oxidative coupling and amination reactions. All these reactions proceed under relative mild reaction conditions and tolerate a wide variety of functional groups, thus avoiding protection group chemistry.
Besides, some reaction typologies offer the possibility to use substrates without prefunctionalized C-X bonds (X = halogens, OTf, etc.) for the construction of complex structures, often poly-heterocyclic systems, as well as the possibility to attain the aim in few steps, and this goal is of considerable importance and not easily obtainable by other methods
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 Formation of Six- and Seven-Membered Ring by Intramolecular Pd-catalyzed Amination of N-allyl-anthranilamides
No full textA divergent synthesis of quinazolin-4-ones and l,4-benzodiazepin-5-ones by Pd(II)-catalyzed intramolecular amination of tosylated N-allyl-anthranilamides is described. Both kinds of products were available in high yields depending on the different reaction conditions
INTRAMOLECULAR HECK REACTION DIRECTED TO THE SYNTHESIS OF MEDIUM-SIZE LACTAMS FUSED TO INDOLE NUCLEUS
No full textPalladium-mediated approach to dibenzo[b,e][1,4]diazepines and benzopyrido-analogues. An efficient synthesis of tarpane
No full text—An original synthetic route toward dibenzo[b,e][1,4]diazepin-11-ones and analogues pyridobenzodiazepinones has been
developed. The method relies upon an intramolecular amination process between an (hetero)aryl halide and the appropriate aniline moiety
Diastereoselective synthesis of enantiopure (aR)-2-methyl-4-(a-phenylethyl)-1,2,3,4-tetrahydro-benzo[e][1,4]diazepin-5-ones
No full text(αR,2R)- and (αR,2S)-2-methyl-4-(α-phenylethyl)-1,2,3,4- tetrahydro-benzo[e][1,4]diazepin-5-ones 7 and 8 were synthesised by an intramolecular azide cycloaddition followed by stereoselective reduction of a bicyclic ketimine
Pd-catalyzed intramolecular cyclization of pyrrolo-2-carboxamides: regiodivergent routes to pyrrolo-pyrazines and pyrrolo-pyridines
No full textTreatment of N-alkyl-N-allyl-pyrrolo-2-carboxamides with catalytic amounts of palladium derivatives gave regioselectively intramolecular cyclizations to generate bicyclic pyrrolo-fused structures. Pyrrolo[1,2-a]pyrazin-1-ones were achieved in high yields by an amination reaction, while pyrrolo[2,3-c]pyridin-7- ones and pyrrolo[3,2-c]pyridin-4-ones were obtained by an oxidative coupling process
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
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