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Natalie Rosenfelder Patrizia Ostrowicz Liangfeng Fu Gordon W. Gribble Sheryl A. Tittlemier Wolfgang Frey Walter Vetter 《Journal of chromatography. A》2010,1217(13):2050-2055
Hexahalogenated 1,1′-dimethyl-2,2′-bipyrroles (HDBPs) are a group of marine halogenated natural products (HNPs) that have been detected in environmental samples from all over the world. The most frequently described congener is the 5,5′-dichloro-1,1′-dimethyl-3,3′,4,4′-tetrabromo-2,2′-bipyrrole (DBP-Br4Cl2, BC-10). This compound is axially chiral, by virtue of hindered rotation about the interannular pyrrole–pyrrole bond forming stable atropisomers. This effect was proven by the separation of synthesized racemic DBP-Br4Cl2 by enantioselective high performance liquid chromatography (HPLC). Pure enantiomers were isolated using enantioselective HPLC. Crystallization led to white crystals studied by X-ray analyses to determine the absolute configuration. Subsequent polarimetric measurements verified the first eluting enantiomer on HPLC as Ra-(+)-DBP-Br4Cl2 and the second as Sa-(−)-DBP-Br4Cl2. We also investigated the gas chromatography (GC) enantioseparation of DBP-Br4Cl2. However, too high temperatures in the injector port led to partial racemization at temperatures >150 °C. GC coupled to mass spectrometry was used to study DBP-Br4Cl2 in marine mammal samples. All samples contained both atropisomers of the natural product DBP-Br4Cl2 with enrichment of the levo (−) enantiomer. This led to the assumption that both enantiomers of DBP-Br4Cl2 were already produced in the environment. 相似文献
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The 1R and 13C NMR spectra of the title compound () reveal through-space couplings between the fluorine and the C-4 methylene group 1H and 13C), as well as coupling between the fluorine and the C-3 methine carbon and the C-2 methylene carbon. 相似文献
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Lothar Bore Tadashi Honda Gordon W. Gribble Enno Lork Jerry P. Jasinski 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o199-o200
The title compound, C32H43NO4·CH4O·H2O, has a nearly planar cyano‐enone A ring in an otherwise normal oleanane triterpenoid. Rings A, B and C are non‐chairs, but rings D and E adopt essentially cyclohexane chair conformations. The structure clearly establishes the C‐D‐E ring stereochemistry as trans‐syn‐cis, as predicted from a nuclear Overhauser effect (NOE) NMR measurement. 相似文献
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Wendy M. Simon Hernando A. Trujillo Erin T. Pelkey Gordon W. Gribble Jerry P. Jasinski 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):461-462
Crystal structure determination of the title molecule, C30H24N2O2S, reveals that the pyrrole ring in this fused heterocycle, although presumably strained and reactive in cycloaddition reactions, does not differ appreciably from N‐methylpyrrole except for a shorter C—C single bond [1.409 (4) Å] in the pyrrole ring. 相似文献
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An efficient synthesis of bruceolline E was completed in three steps from the known ethyl indole-1-carboxylate (9d) in 60% overall yield, via a tandem acylation/Nazarov cyclization with 3,3-dimethyl acrylic acid followed by selenium dioxide oxidation to install the α-diketone functionality. 相似文献
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