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1.
Christophe Hardouin Eric Doris Bernard Rousseau Charles Mioskowski Martine Nierlich 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):225-226
The crystal structure of a methanol–water solvate ofleurosine methiodide, (leurosine‐CH3)+I?·3CH3OH·2H2O (C47H59IN4O9·3CH3OH·2H2O), is described. The piperidine ring of the upper part of the molecule adopts a sofa conformation. An intramolecular hydrogen bond between the tertiary N and the hydroxyl group of the vindoline moiety of the molecule is present. 相似文献
2.
Straightforward access to anhydrovinblastine starting from the parent alkaloid leurosine is reported. The key deoxygenation step was first optimized on a model substrate. However, applied to leurosine, only the low-valent Cp2TiCl gave satisfactory results. 相似文献
3.
James P. Kutney Barbara Aweryn Lewis S. L. Choi Pawel Kolodziejczyk Wolfgang G. W. Kurz Kenneth B. Chatson Friedrich Constabel 《Helvetica chimica acta》1982,65(4):1271-1278
Biotransformation studies of 3′,4′-anhydrovinblastine (1) in Calharanthus roseus cell suspension cultures are reported. A detailed study of one cell line, coded at ?916”?, has revealed that 1 is transformed to the natural bisindole alkaloids leurosine ( 2 ) and Catharine ( 3 ) in approximately 25–30 and 9–16% yield, respectively. In 24–48 h, about 40% of 1 is utilized by the cells. Conditions for biotransformation of 1 have not been optimized so the above yields quoted are not final. 相似文献
4.
James P. Kutney Lewis S. L. Choi Toshio Honda Norman G. Lewis Toshitsugu Sato Kenneth L. Stuart Brian R. Worth 《Helvetica chimica acta》1982,65(7):2088-2101
Cell-free systems from Catharanthus roseus plants are utilized for various studies relating to the biosynthesis of indole alkaloids. Tryptamine ( 5 ) and secologanin ( 6 ), two fundamental building units, are shown to be incorporated into the alkaloid vindoline ( 7 ). In another study, catharanthine ( 18 ) and vindoline ( 7 ) are utilized by this enzyme system and coupled to the important bisindole biointermediate 3′,4′-anhydrovinblastine 1 The previously [20] used name for 17 , 3′, 4′-dehydrovinblastine, is incorrect. ( 17 ). The latter substance is, in turn, incorporated and converted to the natural alkaloids leurosine ( 8 ), Catharine ( 9 ) and vinblastine ( 10 ), thereby providing information about the biosynthesis of these complex molecules. High pressure liquid chromatography assay of the enzymic mixture sheds light on the enzymes involved in the coupling of 18 and 7 . 相似文献
5.
[reaction: see text] The Cp(2)TiCl-mediated deoxygenation of leurosine (1) afforded anhydrovinblastine (4) in good yield. Furthermore, as the reaction proceeded via a carbon-centered radical intermediate, this transient was also trapped by a hydrogen-atom donor to afford selectively reduced alkaloid 10. 相似文献
6.
Carl Th. Pedersen Erik G. Frandsen Kjeld Schaumburg 《Magnetic resonance in chemistry : MRC》1977,9(9):546-552
1H and 13C n.m.r. studies of a series of twelve 1,2-dithiole-3-ylidene ketones and aldehydes have shown that the geometry of the carbon backbone is the same as found in 1,6,6aλ4-trithiapentalenes. No evidence has been found which favours a bicyclic structure for the system. A linear correlation of observed 13C chemical shifts with calculated charge densities is found to be valid. The observations are in agreement with a structure which is a hybrid between a true ketonic structure and a true mesoionic structure. By using the difference in the 13C chemical shifts of ortho and meta carbon atoms in substituent phenyl groups it is possible to qualify the degree of coplanarity of the phenyl groups with the backbone of the molecule. 相似文献
7.
Macrocyclic Spermidine Alcaloids from Pleurostylia africana LOES . The structure of pleurostyline, a new macrocyclic spermidine alkaloid from Pleurostylia africana (Celastraceae), has been elucidated mainly by 1H- and 13C-NMR.-spectroscopy. Pleurostyline represents a new structure type in which spermidine is incorporated in a 13-membered lactam ring to which an additional cinnamoyl residue is fused to yield a 7-membered ring. The same plant contains also the spermidine alkaloids celacinnine and cellallocinnine of which 13C- and high field 1H-NMR.-measurements have been carried out for the first time. Both alkaloids are interconvertible by UV.-irradiation. In addition the existence of rotational isomerism of one amide group of these alkaloids has been demonstrated by NMR.-spectroscopy. 相似文献
8.
Karna Wijaya Oliver Moers Peter G. Jones Armand Blaschette 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):167-169
The crystal structure of the title compound, C5H7N2+·C12H10NO4S2−, consists of two independent cation–anion pairs, A and B. Within each pair, the H—N—C—N*—H grouping (N*—H is the pyridinium function) and one N—S—O moiety of the anion are linked by N*—H⃛N and N—H⃛O hydrogen bonds to form an antidromic ring motif of type R22(8). The remaining amino donors give rise to N—H⃛O hydrogen bonds, connecting the ion pairs into A–B–A–B– chains. The structure testifies to the persistence of the R22(8) motif in question, which was previously detected as a highly robust supramolecular synthon in a series of onium di(methanesulfonyl)amidates. The structure is pseudosymmetric; the anion positions correspond to space group P21/n, but those of the cations do not. 相似文献
9.
The 1-NH structure for 3-azidoindazole has been demonstrated by the observation of 1H? 1H and 13C? 1H couplings involving the hydrogen atom attached to nitrogen. A comparison between 3-azidoindazole and indazole shows that both compounds have the same tautomeric structure. 相似文献
10.
The structure factor of a number of silica suspensions in cyclohexane, with concentrations ranging from 0.01 to 0.714 gcm–3, has been determined with small angle x-ray scattering, using a Kratky camera. The experimental structure factor is compared with a theoretical one for which polydispersity effects on the particle scattering factor and on the structure are explicitly taken into account.Analysis of the scattered intensity at a scattering angle=0 shows that the particles in the suspension interact like hard spheres, with a specific hard sphere volume of 0.61 cm3g–1. A comparison of the experimentally determined structure factor with the structure factor found by a model calculation for a polydisperse system, using the experimental particle size distribution, showed a general agreement. The height of the first maximum agreed well for all concentrations, however its position varied stronger with concentration in the experimental curves. A possible explanation of this effect is given. 相似文献
11.
Gerhard Buchbauer Hanspeter Kählig Helmut Spreitzer Walpurga Wegscheider 《Monatshefte für Chemie / Chemical Monthly》1991,122(12):1089-1095
Summary The separation of a complex mixture of a fragrance material into its isomers is described. Instead of an odour of sandalwood the mixture exhibits mainly a mushroom odour but also the pure isomers show other organoleptic qualities. The structure of two isomers could be ascertained mainly by13C- and1H-NMR-measurements, for two isomers a structure proposal is given.
Herrn Prof. Dr. Wilhelm Fleischhacker mit den besten Wünschen zum 60. Geburtstag gewidmet 相似文献
12.
New Compounds with Garnet Structure. VI. Vanadates The preparation of vanadate-garnets of the following three types is reported: (I) {Na3}[B2III](V3)O12 (BIII = Cr, Sc), (II) {LiCa2}[B2II](V3)O12 (BII = Mg), (III) {Ca2AIII}[Li2] (V3)O12 (AIII = In, Sc). The Cr-compound of type (I) decomposes above 690°C into a mixture of Cr2O3 and NaVO3. The analogous Fe-compound decomposes in a similar way already at 400°C; therefore the preparation by solid state reaction is not possible. Employing larger BIII-ions (Y, Yb, Lu) no garnets of type (I), but mixtures of BIIIVO4 (zircon structure) and Na3BIIIV2O8 are formed. Garnets of type (II) do not exist, when BII are Co and Ni. Mixtures of {Ca3}[LiBII](V3)O12 (garnet structure), LiBIIVO4 (spinel structure) and B3II(VO4)2 are formed. With type (III) for AIII = Y reaction occurs forming a mixture of YVO4, Ca3(VO4)2 and Li3VO4. 相似文献
13.
Sardool S. Ghumman Rajender Singh N. P. S. Sidhu H. S. Sahota 《Journal of Radioanalytical and Nuclear Chemistry》1987,118(6):433-436
The perturbed angular correlation /P.A.C./ technique is employed to investigate the structures of barium ferrite and barium hexaferrite using radioactive133Ba /10.7 Y/ as a probe. The quadrupole interaction frequencies /WQ'S/ are found to be 9.68 and 12.02 Mrad sec–1 for barium ferrite and barium hexaferrite, respectively, showing a drift from usual cubic structure. 相似文献
14.
The structure of single crystals of a substituted diacetylene polymer (pTS) has been investigated by using transmission electron microscopy. It has been found that edge dislocations with Burgers vector parallel to the chain direction are present at a density of up to 1013 m?2. It is suggested that the dislocations may be present first of all in the monomer crystals and become locked into the monomer structure during polymerization. It has been found that the dislocations have a tendency to line up in rows perpendicular to the chain direction and when the density of the dislocations in a row is sufficiently high a small?angle grain boundary can be formed. A possible structure for the dislocations on a molecular level is suggested and the effect of the presence of the dislocations upon the polymerization behavior, mechanical properties, and electric properties is discussed. 相似文献
15.
On Chalcogenolates. 102. Studies on Hemiesters of Monothiocarbonic Acid. 2. Crystal Structure of Rubidium Methyl Oxoxanthate Rb[SOC? OCH3] crystallizes with Z = 4 in the monoclinic space group P21/c with cell dimensions a = 4.332(3) Å, b = 11.349(5) Å, c = 10.673(5) Å, β = 92.9(5)°. The structure has been determined from single crystal X-ray data by means of Patterson and Fourier syntheses and refined to a final conventional R value of 0.045 using 983 independent reflexions. The structure consists of Rb+ and [SOC? OCH3]? ions. The rubidium ion is bonded to five oxygen and three sulfur atoms. The coordination polyhedron is a bicapped trigonal prism. 相似文献
16.
Carlo Castellari Fabio Comelli Stefano Ottani 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):437-438
In the solid‐state structure of the title compound, C4H12N+·C14H10Cl2NO2?·H2O, the asymmetric unit contains one cation, one anion and a water molecule. A complex network of hydrogen bonds is present. A comparison is made with the structure of the anhydrous salt. 相似文献
17.
Bagryanskaya I. Yu. Gatilov Yu. V. Ganbaatar J. Osadchii S. A. Shakirov M. M. Shults E. E. Tolstikov G. A. 《Russian Chemical Bulletin》2001,50(11):2092-2094
Oximation of songorine afforded a mixture of its Z- and E-oximes. The crystal and molecular structure of the Z-isomer was established by X-ray diffraction analysis. Its structure was also confirmed by the spectral data (2D 1H—1H and 13C—1H NMR spectroscopy and mass spectrometry). The structure of isomeric E-oxime was established by comparing its NMR spectroscopic data (1H and 13C) with the data for the Z-isomer. 相似文献
18.
A. B. Terent'ev V. I. Dostovalova R. Kh. Freidlina 《Magnetic resonance in chemistry : MRC》1977,9(6):301-307
13C n.m.r. spectra have been measured for 39 compounds with branched structures including carboxylic acids, their methyl and ethyl esters, nitriles and chlorinated esters. The results obtained indicate that the 13 C n.m.r. technique is applicable to structure assignment of acids and their derivatives containing various numbers of substituents on the chain. The dependence of the carboxylic carbon chemical shift on the number and structure of α-positioned substituents has been determined. Calculation of the chemical shifts for branched carboxylic acids, esters and nitriles from the corresponding increments using the additivity scheme is shown to be possible in principle. 相似文献
19.
Jalilian MR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):976-978
Acetone and n-hexane form an azeotrope with the mole ratio 2:1. As a result of this phenomenon, some characteristic vibrational modes in FT-IR and some chemical shifts in 1H NMR spectra changes. The amount of these changes is an indication of the extension of interaction between two components and their orientation in unit structure of the cluster. FT-IR and 1H NMR spectra of pure substances and their azeotrope were recorded and spectral changes analyzed. Based on mole ratio of constituents, boiling point depressions, spectral changes in fundamental frequencies, and chemical shifts, unit structure of the azeotrope were deduced. 相似文献
20.
The new triterpenoid cycloartane cycloorbigenin C, the structure of which is 23ξ,24ξ-cycloartan-3β,6α,16β,23,24,25-hexaol, was obtained from the aerial part of Astragalus orbiculatus Ledeb. (Leguminosae). The structure of cycloorbigenin C was proved using chemical transformations, IR spectroscopy, electron-impact mass spectrometry, and PMR and 13C NMR spectra interpreted using J-modulation and the 2D NMR spectroscopies: 1H-1H COSY, TOCSY, ROESY, HSQC, and HMBC. 相似文献