Structure de l'opigénine: triterpène pentacyclique isolé d'Opilia celtidifolia

The structure of opigenin, an aglycone from the glycosidic fraction of Opiliaceltidifolia, has been established by study of the genin and its derivatives by means of ir, mass spectroscopy, and 1H and 13C nmr spectroscopy. This is a new triterpene whose skeleton resembles that of 3β-hydroxy lupane but with an isopropyl group in position 20 and an oxymethylene bridge in position 20–28.

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Synthesis, Characterization and Complexation Studies with K + and Ca2+ Cations of trans-1.2-Cyclohexanedioxydiacetamides

Zeitschrift für Naturforschung B ◽

10.1515/znb-1988-0206 ◽

1988 ◽

Vol 43 (2) ◽

pp. 165-170 ◽

Cited By ~ 2

Author(s):

Whei Oh Lin ◽

Maria C. B. V. de Souza ◽

Helmut G. Alt

Keyword(s):

Nmr Spectroscopy ◽

Mass Spectroscopy ◽

H Nmr ◽

Coordination Sites ◽

Complexation Studies ◽

Ir And Nmr Spectroscopy ◽

Elemental Analyses ◽

C Nmr

The synthesis of trans-1.2-cyclohexanedioxydiacetamides starting with trans-1.2-cyclohexane-diol is described. Eleven of these compounds are characterized by IR, 1H NMR, 13C NMR and mass spectroscopy as well as elemental analyses. Most of these compounds are suitable ionophors for the cations K+ and Ca2+. The coordination sites of these ligands in the 1:2 complexes were determined by IR and NMR spectroscopy

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Formation and Identification of Bis[bis(trimethylsilyl)amino]triand tetrachalcogenides

Zeitschrift für Naturforschung B ◽

10.1515/znb-1995-1101 ◽

1995 ◽

Vol 50 (11) ◽

pp. 1575-1582 ◽

Cited By ~ 6

Author(s):

Jari Siivari ◽

Arto Maaninen ◽

Esa Haapaniemi ◽

Risto S. Laitinen ◽

Tristram Chivers

Keyword(s):

Nmr Spectroscopy ◽

Mass Spectroscopy ◽

Elemental Sulfur ◽

Main Product ◽

Elemental Selenium ◽

Analogous Reaction ◽

Reaction Products ◽

Reduced Pressure ◽

Cyclocondensation Reaction ◽

C Nmr

The reaction of (Me3Si)2NLi with SCl2 and elemental sulfur or with Se2Cl2 and elemental selenium leads to the formation of mixtures of bis[bis(trimethylsilyl)amino]suIfides and selenides [(Me3Si)2N]2Ex (E = S or Se; x = 1 - 4 ). The reaction products were identified by mass spectroscopy as well as by 77Se and 13C NMR spectroscopy. The reaction of (Me3Si)2NH with S2Cl2 produces [(Me3Si)2N]2S3 as the main product with only traces of other aminosulfides. [(Me3Si)2N]2S3 was purified by distillation under reduced pressure and identified by elem ental analysis, mass spectroscopy, and by 1H, 13C, and 14N NMR spectroscopy. The successful cyclocondensation reaction of [(Me3Si)2N]2S3 with SCl2 and SO2Cl2 produces S4N2 in 72% yield and provides further verification of the identity of bis[bis(trimethylsilyl)amino]trisulfide. While the analogous reaction of (Me3Si)2NH with Se2Cl2 also leads to the formation of [(Me3Si)2N]2Se3 (48 mol %) as the main product, the reaction mixture contains [(Me3Si)2N]2Se2 and [(Me3Si)2N]2Se4 in significant amounts (17 and 35 mol %, respectively). Attempts to purify the mixture by distillation under reduced pressure resulted only in the formation of a 83:17 mixture of [(Me3Si)2N]2Se2 and [(Me3Si)2N]2Se3.

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Titan- und Vanadiumkomplexe mit 4-[1-(N′-Benzoylhydrazino)-l-phenylmethyliden]- 3-methyl-1-phenyl-pyrazol-5-on. Röntgenkristallstruktur von 4-[1-(N′-Benzoylhydrazino)-1-phenyl-methyliden]-3-methyl-1-phenyl- pyrazol-5-on / Titanium- and Vanadium Complexes of 4-[1-(N′-Benzoylhydrazino)-1-phenylmethylidene]-3-methyl-1-phenyl-pyrazol-5-one. Structure of 4-[1-(N′-Benzoylhydrazino)-1-phenyl-methylidene]-3-methyl-1-phenyl-pyrazol-5-one

Zeitschrift für Naturforschung B ◽

10.1515/znb-1996-0905 ◽

1996 ◽

Vol 51 (9) ◽

pp. 1240-1244 ◽

Cited By ~ 1

Author(s):

Heide Kraudelt ◽

Uwe Schilde ◽

Heike Hefele ◽

Eberhard Ludwig ◽

Erhard Ludwig

Keyword(s):

Molecular Structure ◽

Nmr Spectroscopy ◽

Mass Spectroscopy ◽

Chemical Bonding ◽

Vanadium Complexes ◽

Crystal Data ◽

Space Group ◽

X Ray ◽

Vanadium Ions ◽

C Nmr

By reaction of 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one with benzoylhydrazine the tridentate diacidic ligand 4-[1-(N′-benzoylhydrazino)-1-phenyl-m ethylidene]-3-m ethyl-lphenyl-1-pyrazol-5-one (H2L) is formed which gives complexes ML2 with tetravalent titanium and vanadium ions. The ligand and its complexes were characterized by mass spectroscopy. The vanadium(IV) complex can be oxidised and reduced electrochemicallv. The chemical bonding in the titanium(IV) complex and in the ligand was studied by IR and 13C NMR spectroscopy.The molecular structure of 4-[1-(N′-benzoylhydrazino)-1-phenyl-methylidenel-3-m ethyl-lphenyl- pyrazol-5-one was determined by X-ray analysis. Crystal data: a = 9.159(3) Å, b = 11.014(4) Å, c = 11.136(5) Å, a = 90.11 (2)°, β = 101.84(3)°, γ = 113.01 (2)°; space group P1̄, Z = 2.

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The mechanism of formation of 2,7-dimethyl-2,6-octadiene in the synthesis of 3-methylene-7-methyl-1,6-octadiene

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19831864 ◽

1983 ◽

Vol 48 (7) ◽

pp. 1864-1866

Author(s):

Jan Bartoň ◽

Ivan Kmínek

Keyword(s):

Mass Spectrometry ◽

Nmr Spectroscopy ◽

Alkali Metal ◽

Chromatographic Analysis ◽

Solid Phase ◽

Reaction Pathway ◽

Mechanism Of Formation ◽

Gas Chromatographic Analysis ◽

C Nmr ◽

Visual Observations

2,7-Dimethyl-2,6-octadiene is formed in the catalytic solution for the dimerization of 2-methyl-1,3-butadiene to β-myrcene (3-methylene-7-methyl-1,6-octadiene), as revealed by mass spectrometry and 13C NMR spectroscopy. Visual observations together with the results of gas chromatographic analysis of the catalytic solution suggest that the formation of 2,7-dimethyl-2,6-octadiene is associated with the transition of the alkali metal (sodium) from the solid phase into the solution. A reaction pathway is suggested accounting for the formation of 2,7-dimethyl-2,6-octadiene in the system.

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Non-cyclol (lactame) ergot alkaloids

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19823312 ◽

1982 ◽

Vol 47 (12) ◽

pp. 3312-3317 ◽

Cited By ~ 6

Author(s):

Josef Stuchlík ◽

Alois Krajíček ◽

Ladislav Cvak ◽

Jiří Spáčil ◽

Petr Sedmera ◽

...

Keyword(s):

Nmr Spectroscopy ◽

Ergot Alkaloids ◽

C Nmr

Two new alkaloids were isolated from the field ergot. Their structures, N-(D-lysergyl-L-valyl)cyclo(L-valyl-D-prolyl) (IV) and N-(D-lysergyl-L-valyl)cyclo(L-leucyl-D-prolyl) (V), were assigned by mass, 1H and 13C NMR spectroscopy.

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An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19912917 ◽

1991 ◽

Vol 56 (12) ◽

pp. 2917-2935 ◽

Cited By ~ 1

Author(s):

Eva Klinotová ◽

Václav Křeček ◽

Jiří Klinot ◽

Miloš Buděšínský ◽

Jaroslav Podlaha ◽

...

Keyword(s):

Acetic Acid ◽

Nmr Spectroscopy ◽

Acetic Anhydride ◽

Spectral Methods ◽

X Ray Diffraction ◽

X Ray ◽

Mild Conditions ◽

Condensation Products ◽

Unsaturated Lactones ◽

C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

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A New Dimeric Derivative of Ethoxyquin from Its Reaction with Alkylperoxy Radicals

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19931914 ◽

1993 ◽

Vol 58 (8) ◽

pp. 1914-1918 ◽

Cited By ~ 3

Author(s):

Jaroslav Kříž ◽

Luděk Taimr

Keyword(s):

Mass Spectrometry ◽

Nmr Spectroscopy ◽

Peroxy Radicals ◽

Methyl Group ◽

Alkylperoxy Radicals ◽

C Nmr

The structure of a new compound formed in the reaction of ethoxyquin with alkylperoxy radicals was resolved by 1H and 13C NMR spectroscopy (including COSY, NOESY, HHC RCT and SSLR INEPT techniques) and confirmed by mass spectrometry. The structure suggest participation of 4-methyl group of ethoxyquin in the deactivation of peroxy radicals. A mechanism of this reaction is proposed.

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Reactivity of Sodium Hexaethyl-2,4-dicarba-nido-hexaborate(1-)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19990977 ◽

1999 ◽

Vol 64 (6) ◽

pp. 977-985 ◽

Cited By ~ 17

Author(s):

Bernd Wrackmeyer ◽

Hans-Jörg Schanz ◽

Wolfgang Milius ◽

Catherine McCammon

Keyword(s):

Mössbauer Spectroscopy ◽

Nmr Spectroscopy ◽

Structural Analysis ◽

Hydrogen Atom ◽

Mossbauer Spectroscopy ◽

Sandwich Complex ◽

X Ray ◽

Bromo Derivative ◽

Boron Tribromide ◽

C Nmr

Sodium hexaethyl-2,4-dicarba-nido-hexaborate(1-) (6), available from hexaethyl-2,4-dicarba- nido-hexaborane(8) (4) by deprotonation, reacts with deuterated methanol, CD3OD, to give back 4 without H/D exchange of the B-H-B hydrogen atom. The reaction of 6 with diethylboron chloride, Et2BCl, affords hexaethyl-2,4-dicarba-closo-hexaborane(6) (7), the first example of a peralkylated carborane of this type. In contrast, the reaction of 6 with boron tribromide, BBr3, leads mainly to 2,3,4,5,6,7-hexaethyl-2,4-dicarba-closo-heptaborane(7) (8), together with the corresponding 1-bromo derivative (9) and the closo-carborane 7 as side products. The reaction of two equivalents of 6 with FeCl2 gives the air-stable sandwich complex bis[hexaethyl-2,4-dicarba-nido-hexaborate(1-)]iron 10 which was characterised by X-ray structural analysis. All products were characterised by 1H, 11B and 13C NMR spectroscopy, and 57Fe Mössbauer spectroscopy was used to study 10.

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Formation of spiro adduct from N-methyl-N-(2,4,6-trinitrophenyl)glycine anion

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19890440 ◽

1989 ◽

Vol 54 (2) ◽

pp. 440-445 ◽

Cited By ~ 1

Author(s):

Vladimír Macháček ◽

Alexandr Čegan ◽

Miloš Sedlák ◽

Vojeslav Štěrba

Keyword(s):

Nmr Spectroscopy ◽

Dimethyl Sulfoxide ◽

Equilibrium Constant ◽

Mole Fraction ◽

Nucleophilic Addition ◽

Adduct Formation ◽

First Case ◽

C Nmr

The intramolecular nucleophilic addition of N-methyl-N-(2,4,6-trinitrophenyl)glycine anion in methanol-dimethyl sulfoxide mixtures produces spiro[(3-methyl-5-oxazolidinone)-2,1'-(2',4',6'-trinitrobenzenide)]. The spiro adduct has been identified by means of 1H and 13C NMR spectroscopy. This is the first case when the formation of a Meisenheimer adduct with carboxylate ion is observed. Logarithm of the equilibrium constant of adduct formation increases linearly with the mole fraction of dimethyl sulfoxide in its mixture with methanol.

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