1,721,280 research outputs found
Rural Business Ownership Transitions Study: Findings from surveys and interviews with new business owners
Full text linkThis archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu.Templin, Liz; Chazdon, Scott; Barroso, Felipe; Muske, Glenn; Craig, Wil; Procter, David. (2016). Rural Business Ownership Transitions Study: Findings from surveys and interviews with new business owners. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/197992
Sulfoxide-mediated oxidative cross-coupling of phenols
No full textA metal-free, oxidative coupling of phenols with various nucleophiles, including arenes, 1,3-diketones and other phenols, is reported. Cross-coupling is mediated by a sulfoxide which inverts the reactivity of the phenol partner. Crucially, the process shows high selectivity for cross-versus homo-coupling and allows efficient access to a variety of aromatic scaffolds including biaryls, benzofurans and, through an iterative procedure, aromatic oligomers.</p
Enantio- and diastereoselective synthesis of homopropargyl amines by copper-catalyzed coupling of imines, 1,3-enynes, and diborons
No full textAn efficient, enantio- and diastereoselective, copper-catalyzed coupling of imines, 1,3-enynes, and diborons is reported. The process shows broad substrate scope and delivers complex, chiral homopropargyl amines; useful building blocks on the way to biologically-relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single step.</p
Para-coupling of phenols with C2/C3-substituted benzothiophene S-oxides
No full textC2 and C3 substituted benzothiophenes are common structures in medicinal and materials chemistry. The cross-coupling of phenols with benzothiophenes is a useful route towards these important molecules. In this report we reveal an efficient C–H/C–H-type cross-coupling of benzothiophenes, activated as their S-oxides, with phenols to give C2/C3 arylated benzothiophenes. Whereas previous reports describe cross-coupling at the ortho-position between phenols and sulfoxides, this procedure allows para-functionalization of phenols that typically have their ortho positions blocked.</p
Radical C–C bond formation using sulfonium salts and light
Full text linkSulfonium salts are playing an increasingly significant role in contemporary organic synthesis. In particular, the generation of radicals from sulfonium salts is a fundamental process in Nature and has been the subject of investigation for over 50 years. However, general synthetic methods that use sulfonium salts as radical precursors are rare. The advent of photoredox catalysis has triggered an upsurge of interest in the radical chemistry of sulfonium salts and this review surveys recent applications of aryl and alkyl sulfonium salts in light‐mediated, radical C–C bond formation
Pummerer chemistry of benzothiophene S-oxides: Metal-free alkylation and arylation of benzothiophenes
No full textFunctionalized benzothiophenes are important constructs found in molecules with wide ranging biological activity and in organic materials. An efficient, metal-free approach to C3 and C2 arylated and alkylated benzothiophenes is summarized in this review. The strategy utilizes synthetically unexplored yet readily accessible benzothiophene S-oxides in an interrupted Pummerer/charge accelerated [3,3]-sigmatropic rearrangement cascade process to regioselectively install aryl, allyl or propargyl groups at C3 of benzothiophenes at the expense of C–H bonds. The intermediate sulfonium salts generated after the interrupted Pummerer reaction lack aromaticity and therefore allow the [3,3]-sigmatropic rearrangement, the key C–C bond-forming event, to occur under mild conditions. In addition, a previously unexplored 1,2-migration of substituents in benzothiophenium salts, generated during the cascade process, can be used to access C2 functionalized benzothiophenes
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
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