Das dynamische Verhalten des 1-Methyl-1-benzothiepinium-Ringsystems/The Dynamic Behaviour of the 1-Methyl-1-benzothiepinium Ring System

1981 ◽  
Vol 36 (8) ◽  
pp. 974-977 ◽  
Author(s):  
Hans Hofmann ◽  
Franz Dickert
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
Dynamic Behaviour ◽  
Ring System ◽  
Membered Ring ◽  
Ring Inversion ◽  
Methyl Group ◽  
H Nmr ◽  
Pyramidal Inversion ◽  
Mutual Conversion

Abstract By 1H NMR spectroscopy the stereochemistry of the 1-methyl-1-benzothiepinium ring system was investigated both in thermodynamic and kinetic respects. It was shown that in solution a rapid mutual conversion of the boat shaped seven membered ring system with exo-respectively endo-S-methyl group occurs via a ring inversion and not by a pyramidal inversion at the sulfonium ion. At room temperature predominantly the conformation with the exo-S-methyl group is present.

scholarly journals Photochemische Reaktionen von Übergangsmetall-Olefin-Komplexen, V [1]. Die Umsetzung von Tricarbonyl-η-6.6-dimethylfulven-chrom(0) mit 7-Methyl- und 7-Methoxycycloheptatrien / Photochemical Reactions of Transition Metal Olefin Complexes, V [1]. The Reactions of Tricarbonyl-η-6,6-dimethylfulvene-chromium(0) with 7-Methyl- and 7-Methoxycycloheptatriene

1982 ◽  
Vol 37 (10) ◽  
pp. 1322-1326 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Hans Kurz
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Column Chromatography ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Membered Ring ◽  
Reaction Products ◽  
Methyl Group

Abstract The stereochemistry of the photo reaction products of tricarbonyl-η-6,6-dimethyl-fulvene-chromium(O) (1) with 7-methyl-and 7-methoxycycloheptatriene was studied by NMR-spectroscopy. Both trienes add to 1, displace a CO ligand, and form substituted dicarbonyl-η3-2-cycloheptadienylene-η5-2-cyclopentadienylidene-propane-chromium(0) complexes. With C7H7CH3 only one isomer (3) is formed with the methyl-group in endo-position and the enyl system encompassing C(1′)-C(3′) of the seven membered ring. C7H7OCH3 yields 3 isomers which were separated by column chromatography. 5 has the same constitution as 3. The isomers 4 and 5 bear the OCH3-group in e^o-position. The enyl system of 4 is located on C(1′)-C(3′), that of 6 on C(3′)-C(5′). 6 rearranges at room temperature to 4.

Reactions of 7-azaindole with niobium and tantalum pentachlorides and coupling to the azaindolyl-azaindolium cation

1994 ◽  
Vol 72 (7) ◽  
pp. 1675-1683 ◽  
Author(s):  
Jacques Poitras ◽  
André L. Beauchamp
Keyword(s):  
Infrared Spectroscopy ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Infrared Spectra ◽  
Oxidative Coupling ◽  
Room Temperature ◽  
H Nmr ◽  
Counter Ion ◽  
Distorted Octahedral ◽  
Complex Salts

The reaction of NbCl5 and TaCl5 with 7-azaindole (Haza) at room temperature in benzene or dichloromethane yielded MCl5(Haza) addition compounds. Under more severe conditions, the same compound was obtained with TaCl5. For NbCl5, some reduction to Nb(IV) was observed and NbCl5(Haza), NbCl4(Haza)2, and the (H2aza)+ ion were identified in the reaction mixture by infrared spectroscopy. Oxidative coupling of two azaindole units via N7—C6 also took place during the reaction, since the 7-(azaindol-6-yl)azaindolium cation was found as counter-ion in the crystal structures of two complex salts. In the crystals of (H2aza-aza)[NbOCl4(Haza)]•0.5CH2Cl2([Formula: see text]a = 7.255 Å, b = 12.412 Å, c = 14.277 Å, α = 89.03°, β = 85.60°, γ = 76.66°, Z = 2, R = 0.062), the anion is the roughly octahedral [NbOCl4(azaindole)]− species containing a neutral N7-coordinated azaindole trans to the Nb=O bond. The [NbOCl5]2− salt ([Formula: see text]a = 7.527 Å, b = 10.168 Å, c = 10.467 Å, α = 66.41°, β = 84.07°, γ = 85.51°, Z = 1, R = 0.037) contains the distorted octahedral [NbOCl5]2− ion disordered over two orientations. The infrared spectra suggest monomeric octahedral structures for the MCl5(Haza) and NbCl4(Haza)2 complexes. 1H NMR spectroscopy shows that NbCl5(Haza) is not dissociated in CD2Cl2.

scholarly journals The photoisomerization of cis,trans-1,2-dideuterio-1,4-diphenyl-1,3-butadiene in solution. No bicycle-pedal

2019 ◽  
Vol 18 (9) ◽  
pp. 2174-2179
Author(s):  
Jack Saltiel ◽  
Christopher E. Redwood ◽  
Ratheesh Kumar V. K.
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
H Nmr

cis,trans-1,2-Dideuterio-1,4-diphenyl-1,3-butadiene (ct-DPBd2) was synthesized and its cis–trans photoisomerization in cyclohexane-d12 (C6D12) at room temperature was monitored by 1H NMR spectroscopy.

Übergangsmetall-substituierte Phosphane, Arsane und Stibane, XXX Redoxreaktionen zwischen Triorganodibromphosphoranen oder -arsoranen und Ubergangsmetall -Anionen / Transition-Metal Substituted Phosphanes, Arsanes and Stibanes, XXX Redox Reactions between Triorganodibromophosphoranes or -arsoranes and Transition Metal Anions

1982 ◽  
Vol 37 (7) ◽  
pp. 845-850 ◽  
Author(s):  
Angelika Meyer ◽  
Anna Hartl ◽  
Wolfgang Malisch
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Redox Reactions ◽  
Dynamic Behaviour ◽  
Elevated Temperatures ◽  
Chiral Complexes ◽  
H Nmr ◽  
Analogous Manner ◽  
Metal Anions

Abstract The reaction of the sodium carbonyl metalate Na[W(CO)3Cp] with the phosphorane (Me3SiCH2)3PBr2 results in the formation of (Me3SiCH2)3PandCp(CO)3WBr or [Cp(CO)3W]2, respectively, depending on the solvent used. The redox reactions between Na[Mo(CO)3Cp] and the arsenic analogue (RCH2)3AsBr2 (R = Ph, Me3Si) yield the products Cp(CO)sMoBr and (RCH2)3As. A mechanism involving radicals is discussed. At elevated temperatures the products react further to give the square pyramidal complexes cis-Cp(CO)2[As(CH2R)3]MBr (1, 2a, b) with loss of CO. In an analogous manner Cp(CO)3MBr (M = Mo, W) and (RCH2)3E (E = As, Sb) afford compounds cis-Cp(CO)2[E(CH2R)3]MBr (2c, 3). The dynamic behaviour of the chiral complexes 1, 2a, b, was investigated by 1H NMR spectroscopy.

Cyclische Schwefeldiimide des Siliciums. 15N-NMR-Spektroskopie und die Röntgenstrukturanalyse des Achtrings tBu2Si(NSN)2SitBu2 / Cyclic Sulfur Diimides of Silicon. 15N NMR Spectroscopy and the X-Ray Analysis of the Eight-Membered Ring tBu2Si(NSN)2SitBu2

1993 ◽  
Vol 48 (8) ◽  
pp. 1041-1050 ◽  
Author(s):  
Max Herberhold ◽  
Silke Gerstmann ◽  
Wolfgang Milius ◽  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Pulse Sequences ◽  
Ring System ◽  
Membered Ring ◽  
Coupling Constants ◽  
Primary Amines ◽  
15N Nmr ◽  
Monoclinic Space Group ◽  
Small Magnitude ◽  
X Ray

Various six-membered cyclic sulfur diimides (3a—f) were prepared by aminolysis of the bis(chloro-dimethylsilyl)sulfur diimide (2) using NH3 (a) and primary amines RNH2 [R = Me (b), Et (c), nPr (d), nBu (e), iPr (f)]. Except for R = H, non-cyclic intermediates, the Si-monoamino- (7) and Si,Si′-diamino derivatives of 2 (8), were detetected for all groups R, including R = tBu (g). The reaction between R2SiCl2 and the sulfur diimide anion K[(NSN)SiMe3] gave non-cyclic silanes (9,10) and the eight-membered rings of the type R2Si(NSN)2SiR2 [R = Me (4), tBu (5)] of which 5 was studied by X-ray analysis (monoclinic, space group P21/c; planar ring system) and solid-state 15N and 29Si CP/MAS NMR spectroscopy. The ten-membered ring system 6 was obtained from the reaction between 1,2-dichlorotetramethyldisilane and bis(trimethylstannyl)sulfur diimide. All compounds were studied by 1H,13C, 15N and 29Si NMR. The δ15N NMR data proved useful to distinguish between fluxional systems with fast E/Z—Z/E isomerization (non-cyclic compounds 8 and the ten-membered cycle 6). Hahn-Echo-extended (HEED) polarization transfer (INEPT) pulse sequences served to measure coupling constants 1J(29Si15Namine) for the compounds 3 and 8. This also proved that the magnitude of 1J(29Si15NNSN) must be small (< 1 Hz). In the case of the compounds 3, the rather small magnitude of both 1J(29Si15Namine) and 1J(15N1H) (3a) indicated that the aminonitrogen atom adopts a pyramidal environment.

scholarly journals Stereochemistry of Two Hydroxybiflavanonols from Garcinia cola Nuts

1987 ◽  
Vol 42 (7-8) ◽  
pp. 855-857 ◽  
Author(s):  
Johann Sonnenbichler ◽  
Ifeanyi Madubunyi ◽  
Hugo Scheer
Keyword(s):  
Nmr Spectroscopy ◽  
Absolute Configuration ◽  
Room Temperature ◽  
H Nmr ◽  
The Absolute

The absolute configuration of two hydroxybiflavanonols from Garcinia cola nuts have been determined by CD and 500 MHz 1H NMR spectroscopy. Additionally the occurrence of atrop-isomers at room temperature as the consequence of rotational hindrance in the molecules could be demonstrated.

scholarly journals Crystal structure of ethyl 2-[2-(4-methylbenzoyl)-5-p-tolyl-1H-imidazol-1-yl]acetate

2016 ◽  
Vol 72 (3) ◽  
pp. 347-349
Author(s):  
E. Arockia Jeya Yasmi Prabha ◽  
S. Suresh Kumar ◽  
Anil K. Padala ◽  
Qazi Naveed Ahmed ◽  
S. Athimoolam
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Ethyl Acetate ◽  
Imidazole Ring ◽  
Ring System ◽  
Membered Ring ◽  
Dihedral Angles ◽  
Methyl Group ◽  
Compound C ◽  
Phenyl Rings

In the title compound, C22H22N2O3, the plane of the five-membered ring is oriented at dihedral angles of 45.4 (1) and 52.5 (1)° to the phenyl rings. Furthermore, this ring makes an angle of 85.2 (2)° with the plane of the ethyl acetate substituent. The molecular structure is affected by an intramolecular C—H...O hydrogen bond between an H atom from thep-tolyl group and the carbonyl O atom of the acetate. The methyl group of the ethyl acetate residue is disordered over two sites with equal occupancies. The crystal structure features intermolecular C—H...O and C—H...N interactions. One of the C—H...O hydrogen bonds forms aC(5) chain motif extending along theaaxis. In addition, C—H...N contacts form inversion dimers withR22(12) ring motifs, linking the imidazole ring system to the benzene ring of thep-tolyl substituent.

Dynamic Behaviour of Tetramethylethylene Diamine (TMEDA) Ligands in Solid Organolithium Compounds: A Variable Temperature 13C and I5N CP/MAS NMR Study

1995 ◽  
Vol 50 (4-5) ◽  
pp. 429-438 ◽  
Author(s):  
Wolfgang Baumann ◽  
Yuri Oprunenko ◽  
Harald Günther
Keyword(s):  
Nmr Spectroscopy ◽  
Energy Barrier ◽  
Dynamic Behaviour ◽  
Variable Temperature ◽  
Mas Nmr ◽  
Organometallic Complexes ◽  
Dynamic Processes ◽  
Ring Inversion ◽  
Nmr Study ◽  
Cp Mas Nmr

Abstract The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)μ-Ph]2 (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS 13C and 15N as well as 7Li MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol-1, respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA ligands or a ring inversion of the central four-membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180° ring flips of the Li-TMEDA groups, which are characterized by an energy barrier ΔG" (317) of 64 kJ mol-1

X+ transfer from the halonium ions of adamantylideneadamantane to acceptor olefins. The possibility of chiral induction in the transfer process

1997 ◽  
Vol 75 (12) ◽  
pp. 1844-1850 ◽  
Author(s):  
Alexei A. Neverov ◽  
Theresa L. Muise ◽  
R.S. Brown
Keyword(s):  
Nmr Spectra ◽  
Room Temperature ◽  
Reaction Rate ◽  
Methyl Groups ◽  
Kinetic Behavior ◽  
Methyl Group ◽  
Chiral Induction ◽  
H Nmr ◽  
Group 12 ◽  
Kinetics Of

The bromonium ion of adamantylideneadamantane (Ad=Ad-Br+) has been used to induce the bromocyclization of a 4-pentenyl glycoside (10) and a 5-hexenyl glycoside (11) in dichloroethane. The kinetics of these processes have been studied at 25 °C in the presence of varying [Ad=Ad] and, in the case of the transfer to 10, in the presence of pentanol. The second-order rate constants for bromocyclization of these two alkenes are (1.04 ± 0.06) × 10−1 M−1 s−1 and (5.34 ± 0.2) × 10−1 M−1 s−1, respectively, and in no case does added Ad=Ad or pentanol alter the reaction rate. The kinetic behavior is interpreted in terms of cyclization occurring directly from a 1:1 complex of Ad=Ad-Br+ and 10 or 11. The chiral induction for the bromocyclization of 10 promoted by AdAd-Br+ was measured at 20% e.e., the (−)-(S)-tetrahydrofurfuryl bromide being the dominant stereoisomer. Ad=Ad molecules substituted at one of the homoallylic carbons by an axial methyl group (12), or by two methyl groups (axial and equatorial), were synthesized and the 1H NMR spectra of their bromonium ions is given. These materials are not stable for prolonged times at room temperature. A limited kinetic study of the reaction of 12-Br+ and 4-pentenol indicated that the Br+ transfer is 500 times faster than the comparable transfer from Ad=Ad-Br+ to 4-pentenol. The possibility of using these materials to induce chiral bromocyclization is discussed. Keywords: bromonium ion, halonium, transfer, chiral, adamantylideneadamantane.

Studies in Vilsmeier-Haack reaction. Application to quinoxalinones

1990 ◽  
Vol 55 (11) ◽  
pp. 2715-2721 ◽  
Author(s):  
Ibrahim M. A. Awad ◽  
Khairy M. Hassan
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Antimicrobial Activities ◽  
Heterocyclic Amines ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Methyl Group ◽  
H Nmr ◽  
Quinoxalinone Derivatives

The 3-methyl group in quinoxalinones I and II has been found to undergo diformylation by Vilsmeier reagent to give the corresponding aminoacrolein derivatives (III, IV). Condensation and/or interaction of III or IV with some secondary heterocyclic amines and/or with hydrazine, phenylhydrazine and hydroxylamine affords the related 3-methyl-N-(1H)-2-quinoxalinone and 1,3-dimethyl-2-quinoxalinone derivatives (VII-XVIII), some with pronounced fluorescence activities. All synthesized compounds have been screened in vitro for their antimicrobial activities against Gram-positive and Gram-negative bacteria. The structures of these compounds were confirmed by elemental analysis, IR and 1H NMR spectroscopy.

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