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Synthesis of various angular methylfurocoumarins
No full textA number of new methylfurocoumarins, in wich the furan, benzene and pyrone rings are annulate angularly with various arrangements, were synthesized. The synthesis were performed starting from the appropriate hydroxycoumarins on which the furan ring was built. According to this scheme, methyl groups could be introduced into positions which look most promising for enhancement of photoreactivity in the respect to the corresponding unmethylated compounds
Methyl derivatives of tetrahydrobenzo- and benzofurocoumarins, a new class of potential photoreagents toward DNA
No full textMETHYLTRIAZOLOCOUMARINS - NEW FUROCOUMARIN ISOSTERS AS POTENTIAL PHOTOCHEMOTHERAPEUTIC AGENTS
No full textA number of new methyltriazolocoumarins were synthesized. The synthesis was performed starting from the appropriate methylated 7-aminocoumarins which were nitrated, reduced and diazotized with concomitant cyclization to form the triazole ring
Difurocoumarins: Psoralen analogs as photochemotherapeutic agents
No full textNew tetracyclic psoralen-like compounds have been synthesized, which are characterized by two furan rings angularly condensed on the coumarin nucleus and are therefore called difurocoumarins. This structural feature may favour the intercalation into the DNA helix and then monofunctionally photoreaction with DNA bases. Their synthesis started from 5,7-dihydroxy-4-methylcoumarin, which was condensed with alpha -haloketones; the resulting ketoethers were then cyclized to give the title compounds
4',5'-Substituted methylangelicins: photocycloaddition with pyrimidine bases of DNA.
No full textThe isolation and characterization of photocycloadducts with pyrimidine bases from DNA samples irradiated (365 nm) in the presence of four 4',5'-substituted methylangelicins was performed. All these furocoumarins yielded mainly the cis-syn furan-side cycloadduct with thymine. For 4',5'-dimethyl-, 5,4',5'-trimethyl- and 6,4',5'-trimethylangelicin this adduct was accompanied by two pyrone-side adducts (cis-syn and cis-anti), whereas the 4,4',5'-trimethyl derivative gave the furan-side adduct with cytosine. The characterization of the regio- and stereochemistry of the adducts was accomplished by H-1 NOE (nuclear Overhauser effect) and H-1-C-13 HMBC (heteronuclear multiple-bond connectivity) spectroscopies. The formation of different cycloadducts in DNA by the various derivatives highlights the role of the methyl groups in determining the regio- and stereochemistry of the cycloaddition
Photoreaction between 4,7-dimethylallopsoralen and DNA: isolation of a fluorescent cycloadduct between the furocoumarin and thymine.
No full textSynthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins
No full textNew linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7-mercaptocoumarin, which were condensed with chloroketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins and thiopyranocoumarins
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
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