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ALLYLSTANNATION .13. NEW SYNTHESIS OF UNREPORTED ETHERS FROM 4-NORMAL-BUTYLDICHLOROSTANNOXY-HEPTA-1,5-DIENE, 3-METHYL-4-NORMAL-BUTYLDICHLOROSTANNOXY-HEPTA-1,5-DIENE AND 4-NORMAL-BUTYLDICHLOROSTANNOXY-NONA-1,5-DIENE
No full textALLYLSTANNATION .11. A NEW CONVENIENT METHOD FOR THE SYNTHESIS OF 9-CHLORO-2,4-DIETHYL-CIS-3-OXABICYCLO [3.3.1] NONANE
No full textALLYLSTANNATION .12. NEW APPROACH TO ALKENYL-N-ALKYL AND ALKYNYL-N-ALKYL CARBAMATES BASED ON THE SELECTIVE INSERTION OF ALDEHYDES INTO THE ALKENYL-N-ALKYL AND ALKYNYL-TIN BONDS
No full textGAS-LIQUID-CHROMATOGRAPHY, THIN-LAYER CHROMATOGRAPHY AND C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROMETRY IN THE ANALYSIS OF DIASTEREOMERIC MIXTURES OF R-CH(OH)-CH(CH3)-CH=CH2 ALCOHOLS
No full textGas-liquid chromatography, thin-layer chromatography and 13C NMR spectrometry have been employed to identify and analyse diastereomeric mixtures of the β-methylalcohols RCH(OH)-CH(CH3)-CHCH2 where R = CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, iso-C3H7, sec.-C4H9, tert.-C4H9. The existence of a relationship between the analytical data and diastereomeric configuration of the alcohols is pointed out for all the three methods adopte
THE PREPARATION OF 4-CHLORO-2,6-DIALKYL-, 4-BROMO-2,6-DIALKYL-, (E/Z)-4-CHLORO-2,6-DIALKYL-3-METHYL-AND (E/Z)-4-BROMO-2,6-DIALKYL-3-METHYL-TETRAHYDROPYRANS BY CONDENSATION OF ALDEHYDES WITH DI-HALIDES AND TRI-HALIDES OF ALLYLTIN .9.
No full textThe reaction recently discovered leading to tetrahydropyrans (THP): has been more extensively investigated by using various allyltin systems, alternate incremental additions of two aldehydes, and scrambling organotin reagents. Unsymmetric halotetrahydropyrans containing various R groups can be readily prepared in this way.
The thermal breakdown of the 12-dichloro adducts, namely (E/Z)1-alkyl-1-butyldichlorostannoxy, 1-alkyl-3-pentyl ethers and the (threo/erythro)-1-alkyl-1-butyldichlorostannoxy, 1-alkyl-2-methyl-3-butenyl ethers, is a stereospecific reaction which affords (E/Z)-halotetrahydropyrans, where the isomerism is at the CHClCH(CH3) bon
HYDRATED SIGMA-BONDED ORGANOMETALLIC CATIONS IN ORGANIC-SYNTHESIS .1. ALLYL-STANNATION, CROTYL-STANNATION, 1-METHYLALLYL-STANNATION, CYCLOHEX-2-ENYL-STANNATION, AND CINNAMYL-STANNATION OF CARBONYL-COMPOUNDS IN WATER
No full textHomoallylic alcohols can be prepared in water by allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, or cinnamyl-stannation of such carbonyl compounds as aldehydes, dialdehydes, and ketones, as well as acetals. The procedure is based on: Bu2RSnCl + R′COR′′ + 12H2O → R(HO)CR′R′′ + 12(Bu2SnCl)2O ↓ where R = allyl, crotyl, 1-methylallyl, cyclohex-2-enyl, or cinnamyl group, R′ = H or alkyl group, R′′ ≠ R′ = alkyl group. In most cases, the reaction products are obtained rapidly in high yields (80–100%). Hydrated organometallic cations Bu2RSn+(aq) are partly involved. These results, together with those already published on 2-propynyl- and allenyl-stannation, indicate the value of this procedure
THE CRYSTAL-STRUCTURE OF TRIPHENYLALLYLTIN
No full textThe crystal structure of (C6H5)3SnCH2CHCH2 has been determined. The asymmetric unit consists of two molecules of triphenylallyltin having virtually the same conformation. Their geometrical parameters exclude pπ-dπ bonding between the metal and the allyl double bond, and seem to be in a better agreement with a σ-π conjugation effec
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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