scholarly journals Selektive Metallierung von BicycIo[3.2.1]octa-2,6-dien, II Distannylierte Derivate und stannylierte tricyclische Sekundärprodukte / Selective Metalation of Bicyclo[3.2.1]octa-2,6-diene, II Distannylated Derivatives and Stannylated Tricyclic Secondary Products

1988 ◽  
Vol 43 (11) ◽  
pp. 1405-1415 ◽  
Author(s):  
N. Hertkorn ◽  
F. H. Köhler
Keyword(s):  
Nmr Spectroscopy ◽  
Low Temperature ◽  
Nmr Spectra ◽  
Considerable Change ◽  
Coupling Constants ◽  
Secondary Products ◽  
Starting Compound ◽  
Derivatives Of ◽  
C Nmr ◽  
Dibromo Derivative

Abstract Distannylated bicyclo[3.2.1]octa-2,6-diene (1) with (CH3)3 Sn groups in positions exo-4 and 7 (7a), endo-4 and 7 (7b), exo-4 and 6 (7c), and probably exo-4 and endo-4 (7d) are obtained when 1 is treated first with an excess of n-BuLi/t-BuOK in alkane and then with (CH3)3 SnCl. Byproducts are monostannylated derivatives of 1 and l,4-bis(trimethylstannyl)but-2-ene (3). The formation of 7a/b/c is best understood when the two possible bicyclo[3.2.1]octa-2,6-dienyl dianions are generated as intermediates. 3,exo-4-Bis(trimethylstannyl)bicyclo[3.2.1]octa-2,6-diene (7e) is ob-tained from the corresponding dibromo derivative of 1 and (CH3)3SnLi with 3-bromo-exo-4-trimethylstannylbicyclo[3.2.1]octa-2,6-diene (9) as an intermediate. The bicyclic stannyl com-pounds are susceptible to a 1,5-homopentadienyl shift of a (CH3)3Sn group at relatively low temperature when the starting compound has the stannyl group in position 4 of 1 and when positions 6 or 7 are unsubstituted. Tricyclo[3.2.1.02.7]oct-3-enes with (CH3)3Sn groups in positions exo-6 (5a), endo-6 (5b), 3 and exo-6 (10a), and 3 and endo-6 (10b) are thus obtained. On further heating, 10b gives l-trimethylstannyl-3-vinylbenzene (11). All compounds have been studied systematically by NMR spectroscopy including δ(119Sn), δ(13C), δ(1H), 4/5J(119/117Sn-119Sn), nJ(119/117Sn-13C) , nJ(119/117Sn-1H), 1J(13C-1H ) , and nJ(1H-1H ). Among all nuclei, 119Sn gives the most simple spectra. From the 13C NMR spectra a series of useful increments of (CH3)3Sn groups emerges. The most interesting coupling constants are 5J(119/117Sn-119Sn), for which a considerable change with the dihedral angle is established, and nJ(119/117Sn-13C). For n = 3 and 4 the latter are especially useful because their angular dependence leads to unambiguous signal assignments.

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

Hochauflösungs-13C-NMR-Spektroskopie, VI [1]. Strukturabhängigkeit der 13C,H-Kopplungskonstanten in 6.6-disubstituierten Fulvenen / High Resolution 13C NMR Spectroscopy, VI [1]. Structure Dependence of the 13C,H Coupling Constants in 6,6-Disubstituted Fulvenes

1980 ◽  
Vol 35 (12) ◽  
pp. 1572-1574 ◽  
Author(s):  
Siegmar Braun ◽  
Ulrich Eiehenauer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
High Accuracy ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Structure Parameters ◽  
Structure Dependence ◽  
C Nmr

In order to study the structure dependence of the 13C,H couplings in the fulvene system the 1H-coupled 13C NMR spectra of 6,6-disubstituted fulvenes (R = R′ = C6H5, CH3, cyclopropyl and N(CH3)2) were recorded and the interesting couplings determined with high accuracy by complete analysis. They have values typical for unsaturated five membered rings with vastly localised double bonds like cyclopentadiene-1,3 and spiro[2.4]heptadiene- 4,6 and show characteristic correlations with structure parameters.

Pertrimethylsilylation as a method for improvement of chemical shift additivity through conformational homogenization. 1H and 13C NMR spectra of pertrimethylsilylated derivatives of methyl β-D-xylopyranosides

1983 ◽  
Vol 48 (7) ◽  
pp. 1829-1841 ◽  
Author(s):  
Jan Schraml ◽  
Eva Petráková ◽  
Otomar Pihar ◽  
Ján Hirsch ◽  
Václav Chvalovský
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Population Analysis ◽  
Coupling Constants ◽  
Proton Proton ◽  
1H And 13C Nmr ◽  
Proton Coupling ◽  
Derivatives Of ◽  
C Nmr

All possible mono-, di-, and tri- O-methyl, O-benzyl, O-benzoyl, and O-acetyl derivatives of methyl β-D-xylopyranoside were fully trimethylsilylated and their 1H and 13C NMR spectra measured in deuteriochloroform solutions. The spectra were analysed and the chemical shifts completely assigned on the basis of decoupling experiments. The proton-proton coupling constants vary only very little throughout the series. Conformer population analysis by the method of average coupling constants shows that trimethylsilylation increases the C1 conformer population and makes the series conformationally homogenous. Owing to this conformational homogeneity chemical shifts (both 1H and 13C) satisfy very well direct additivity rule. It is suggested that pertrimethylsilylation should be employed whenever deviations from chemical shift additivity are caused by conformational mobility of the investigated series of compounds and when bulky groups can stabilize one of the conformers.

(9H-Fluoren-9-ylidene)fluoromethyllithium, a Stabilized Fluoroalkenyl Carbanion. Preparation, Reactions, 13C and 19F NMR Spectra

2001 ◽  
Vol 66 (10) ◽  
pp. 1508-1520 ◽  
Author(s):  
Jaroslav Kvíčala ◽  
Andrew Pelter
Keyword(s):  
Nmr Spectroscopy ◽  
Low Temperature ◽  
Methyl Iodide ◽  
Nmr Spectra ◽  
19F Nmr ◽  
19F Nmr Spectra ◽  
13C And 19F Nmr ◽  
C Nmr

(9H-Fluoren-9-ylidene)fluoromethyllithium (1) was prepared by a low-temperature transmetallation of bromo(9H-fluoren-9-ylidene)fluoromethane (2). Whereas the synthesis of unlabeled bromofluoroalkene 2a was based on Wittig-Horner reaction of fluorenone (3) with ethyl (diethoxyphosphoryl)fluoroacetate (4), (1-13C)-labeled compound 2b was obtained via an addition of labeled lithium 1-ethoxy-2-fluoro(2-13C)ethen-1-olate (5) to ketone 3. Fluoroethenyllithium 1 was found by a low-temperature 19F NMR spectroscopy to be stable up to -40 °C; it was reacted with the series of electrophiles, e.g. benzaldehyde (6), methyl iodide (7) or chloro(trimethyl)silane (8). 13C NMR experiments with (1-13C)-labeled 1a proved that fluorocarbenoid 1 is probably monomeric in THF solution in analogy to other halocarbenoids.

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

1981 ◽  
Vol 46 (8) ◽  
pp. 1913-1929 ◽  
Author(s):  
Bohdan Schneider ◽  
Pavel Sedláček ◽  
Jan Štokr ◽  
Danica Doskočilová ◽  
Jan Lövy
Keyword(s):  
Ethylene Glycol ◽  
Vibrational Spectra ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Conformational Structure ◽  
Infrared And Raman Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Crystalline Forms ◽  
C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

E-Homolupane Derivatives Substituted in Position 17 and 22a. 1H NMR, 13C NMR and IR Spectra

1995 ◽  
Vol 60 (4) ◽  
pp. 619-635 ◽  
Author(s):  
Václav Křeček ◽  
Stanislav Hilgard ◽  
Miloš Buděšínský ◽  
Alois Vystrčil
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Coupling Constants ◽  
Side Chain ◽  
Oxidation Reactions ◽  
H Nmr ◽  
Complete Assignment ◽  
Nmr Techniques ◽  
Intramolecular Association ◽  
C Nmr

A series of derivatives with various oxygen functionalities in positions 17,22a or 19,20 was prepared from diene I and olefin XVI by addition and oxidation reactions. The structure of the obtained compounds was confirmed by 1H NMR, 13C NMR and IR spectroscopy. The kind of intramolecular association of the 17α-hydroxy group was studied in connection with modification of the side chain and substitution in position 22a. Complete assignment of the hydrogen signals and most of the coupling constants was accomplished using a combination of 1D and 2D NMR techniques. The 1H and 13C NMR spectra are discussed.

Preparation of 2,3-Dideoxy-2,3-epimino and 3,4-Dideoxy-3,4-epimino Derivatives of 1,6-Anhydro-β-D-hexopyranoses by Mitsunobu Reaction

1998 ◽  
Vol 63 (6) ◽  
pp. 813-825 ◽  
Author(s):  
Jiří Kroutil ◽  
Tomáš Trnka ◽  
Miloš Buděšínský ◽  
Miloslav Černý
Keyword(s):  
Nmr Spectra ◽  
Mitsunobu Reaction ◽  
Derivatives Of ◽  
C Nmr

A series of new 2-, 3- and 4-benzylamino-2-, 3- and 4-deoxy derivatives of 1,6-anhydro-β-D-hexopyranoses were prepared from 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexopyranoses by treatment with benzylamine and converted into 2,3-(N-benzylepimino)-2,3-dideoxy- and 3,4-(N-benzylepimino)-3,4-dideoxy-β-D-hexopyranoses of the D-allo, D-galacto and D-talo configuration by Mitsunobu reaction. The structures of benzylamino and benzylimino derivatives were confirmed by 1H and 13C NMR spectra.

Nuclear magnetic resonance studies on the anions [M(SnCl3)5Cl]4− (M = Ru, Os) and [Ru(SnCl3)5(MeCN)]3−: the X-ray crystal structure of [N(C2H5)4]4[Ru(SnCl3)5Cl]

1982 ◽  
Vol 60 (11) ◽  
pp. 1304-1316 ◽  
Author(s):  
Louis J. Farrugia ◽  
Brian R. James ◽  
Claude R. Lassigne ◽  
Edward J. Wells
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Octahedral Geometry ◽  
Coupling Constants ◽  
Order Effects ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
Crystallographic Study

The octahedral anions [M(SnCl3)5Cl]4− (M = Ru, Os) have been fully characterized by 119Sn FT nmr spectroscopy. For M = Ru, 117Sn and 115Sn nmr spectra were also recorded, and an X-ray crystallographic study was carried out on the tetraethylammonium salt, isolated as a disolvate from acetonitrile. The Ru—Sn bond lengths indicate some degree of dπ–dπ interactions. The slight distortions from octahedral geometry are discussed in connection with the packing of the chlorine atoms. The Sn nmr spectra reveal the first observed coupling to a 99Ru nucleus (I = 5/2, 12.7% natural abundance), very large 2J(119Sn—117Sn) coupling constants, and the first observed second-order effects on a heteronuclear system. The octahedral anion [Ru(SnCl3)5(MeCN)]3− was also synthesized as the tetraethylammonium salt and characterized spectroscopically.

Notizen: 13C-NMR an paramagnetischen Phenylmetallocenen1: Analogie zum Benzylradikal.

1976 ◽  
Vol 31 (8) ◽  
pp. 1153-1154 ◽  
Author(s):  
Frank H. Köhler ◽  
G. Matsubayashi
Keyword(s):  
Density Distribution ◽  
Spin Density ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Hyperfine Coupling ◽  
Spin Density Distribution ◽  
Coupling Constants ◽  
Methyl Radicals ◽  
Benzyl Radical ◽  
C Nmr

The 13C NMR spectra of seven phenylated paramagnetic metallocenes have been recorded. From the spectra the 13C hyperfine coupling constants A(13C) have been extracted and compared with corresponding A(1H). It is found that the phenyl A′s in nickelocenes and cobaltocenes behave as in benzyl radical being reduced by a factor of 27. This offers a new route to informations about spin density distribution in substituted methyl radicals.

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