Results 221 to 230 of about 3,055,660 (264)
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The absolute configuration of physostigmine
Tetrahedron, 1969Abstract Physostigmine, the toxic alkaloid of the Calabar bean, has been degraded systematically to (+)-1,3-dimethyl-3-ethyloxindole (Chart 1), which contains only one of the original asymmetric centers. The enantiomorph of this oxindole was then synthesized from (R)-(−)-2-methyl-2-phenylbutyric add, a substance of known configuration, allowing the ...
R K, Hill, G R, Newkome
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The absolute configuration of (−)-Aspidospermine
Experientia, 1968Die absolute Konfiguration von (−)-Aspidospermin-N(b)-jodemthylat wurde rontgenographisch unter Anwendung der anomalen Streuung bestimmt. Dadurch ist die absolute Konfiguration von (−)-Aspidospermin festgelegt.
B M, Craven, D E, Zacharias
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Absolute Stereochemical Configuration of Morphine
Nature, 1952THE morphine molecule contains five asymmetric carbon atoms and five interlocking ring systems, and constitutes a complicated three-dimensional structure the stereochemistry of which has recently attracted considerable interest. The initial suggestions of Schopf1 concerning the relative orientations at the asymmetric carbons 5, 9, 13 and 14 were ...
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Absolute configuration of fucoxanthin
Tetrahedron Letters, 1976Abstract The common natural isomer of the allenic carotenoid fucoxanthin has the 3S,5R,6S,3′S,5′R,6′R configuration.
K. Bernard +3 more
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Absolute configuration of neostenine
Journal of Molecular Structure, 2010Abstract Heavy atoms bromine and iodine were incorporated into the neostenine ( 1 ) skeleton through reductive cleavage of the lactone ring, followed by acylation with 4-bromobenzoyl chloride, and salt formation with methyl iodide, respectively. The absolute configuration of the seven chiral centers C1, C9, C9a, C10, C11, C1 and C13 in 1 were ...
Ren-Wang Jiang +4 more
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Absolute configurations of isoflavans
Phytochemistry, 1978Abstract The absolute configurations of isoflavans and isoflavanquinones isolated from Cyclolobium, Dalbergia and Machaerium species were established by comparison of their ORD curves with that of (3S)-5,7,3′,4′-tetra-methoxyisoflavan and (3S)-7,4′-dimethoxyisoflavan-2′,5′-quinone, respectively.
Kazu Kurosawa +5 more
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Absolute configuration of aleuriaxanthin
Phytochemistry, 1976Abstract The chirality of aleuriaxanthin ex Aleuria aurantia has been shown to be 2′ R by means of the modified Horeau method. Other carotenoids with terminal methylene in an acylic end group were not detected in A. aurantia .
Richard Bucheckert +2 more
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Absolute Configuration of Gilmaniellin
Helvetica Chimica Acta, 1984AbstractThe absolute configuration of dechlorogilmaniellin (2) could be determined from its chiroptical data by applying coupled‐oscillator theory to the CD couplet around 272 nm and from the sign of its n →π* Cotton effect. Gilmaniellin (1) has the same absolute configuration.
GÜNther Snatzke, Christoph Tamm
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Absolute configuration of isocurcumenol
Acta Crystallographica Section C Crystal Structure Communications, 1999The absolute configuration of isocurcumenol, C 15 H 22 O 2 was determined as (3α,3aα,6α,8aβ). The C=C double bonds in the 5-isopropylidene and 8-methylene groups were confirmed. The molecules are arranged by intermolecular hydrogen bonds between the hydroxyl groups to form helices about 3 2 screw axes.
J. W. Bats, S. H. Öhlinger
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Absolute configuration of conhydrine
Canadian Journal of Chemistry, 1969Catalytic hydrogenation of optically active 2-pyridyl ethylcarbinol (1) formed the alkaloid conhydrine (2) stereospecifically. Application of the von Braun reaction gave conversion of (+)-conhydrine into R-(−)-3-octyl benzoate and of (−)-conhydrine into the S-(+)-antimer.
G. Fodor +2 more
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