Conformational analysis of the bicyclo - [4.4.1]undecan-11-one ring system

2002 ◽  
Vol 80 (3) ◽  
pp. 245-249
Author(s):  
Masood Parvez ◽  
Ted S Sorensen ◽  
Fang Sun
Keyword(s):  
Conformational Analysis ◽  
Symmetry Plane ◽  
Ring System ◽  
Line Broadening ◽  
X Ray ◽  
The One ◽  
Effective Development ◽  
System 1 ◽  
C Nmr ◽  
Dibromo Derivative

The first conformational analysis of a bicyclo[4.4.1]undecan-11-one system (1) is presented. Based on low-temperature 13C NMR line-broadening measurements and an X-ray structure of the 1,6-dibromo derivative (2), this ketone adopts a chiral conformation with approximate C2 symmetry about an axis containing the >C=0 bond. The observed NMR line-broadening results are consistent with a dynamic interchange of M and P enantiomeric C2 conformations, or expressed another way, the "effective" development of an additional Cs symmetry plane bisecting the molecule at right angles to the plane containing the one carbon bridge (overall average C2v symmetry). This process has a ΔH‡ barrier of 42 kJ mol–1 for ketone 1 (43 kJ mol–1 for 2).Key words: bicyclo[4.4.1]undecan-11-one, conformational analysis, NMR line broadening, X-ray structure, enantiomers.

Zur Struktur des Enols von Benzoylaceton / On the Structure of the Enol of Benzoylacetone

1979 ◽  
Vol 34 (11) ◽  
pp. 1606-1611 ◽  
Author(s):  
W. Winter ◽  
K.-P. Zeller ◽  
S. Berger
Keyword(s):  
Structural Model ◽  
Chemical Shifts ◽  
Ring System ◽  
Coupling Constants ◽  
Spin Coupling ◽  
X Ray ◽  
Wide Range ◽  
Spin Coupling Constants ◽  
C Nmr ◽  
Oxygen Atoms

Abstract A low temperature X-ray study of the enol of benzoylacetone indicates fixed positions of the C and O atoms within the enolic ring system and an extensive bond delocalisation over these atoms. The distribution of electron density between the two oxygen atoms shows that the enolic hydrogen is spread over a wide range. This is in accordance with a structural model proposed by de la Vega, whereupon the C and O atoms are kept fixed in their average positions during a tunneling process of the hydrogen between the two oxygen atoms. With this conception, the chemical shifts in the 17O and 13C NMR spectra, the 13C13C spin coupling constants and the temperature independance of these values can be explained.

1,2-Bis(1-aryl-3-alkyltriazen-3-yl)ethanes and related compounds

1998 ◽  
Vol 76 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Donald L Hooper ◽  
Ian R Pottie ◽  
Marc Vacheresse ◽  
Keith Vaughan
Keyword(s):  
Nmr Spectroscopy ◽  
Line Broadening ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Ir And Nmr Spectroscopy ◽  
Diazonium Coupling ◽  
Significant Line ◽  
Related Compounds ◽  
C Nmr

A series of novel bistriazenes, the 1,2-bis(1-aryl-3-methyltriazen-3-yl)ethanes, Ar-N T N-NMe-CH2CH2-NMe-N T N-Ar, have been synthesized by diazonium coupling with N,N'-dimethylethylenediamine. These bistriazenes are stable crystalline compounds and have been unequivocally characterized by IR and NMR spectroscopy (1H and 13C), and elemental analysis. The structures of two compounds in the series have been confirmed by X-ray crystallography. The 1H NMR spectra show significant line broadening of the N-methyl resonances arising from the restricted rotation around the N2-N3 bond of the triazene units. The presence of strongly electron-withdrawing groups on the aryl ring restricts the rotation to the point where the N-methyl signals of the rotamers are distinct even at room temperature; four resonances of the N-methyl signal are clearly evident and these can be assigned to the anti-anti, syn-syn, and syn-anti conformations of the bistriazene. Diazonium coupling with N,N'-diethylethylenediamine affords the N,N'-diethyl homologues of the bistriazenes, which have been similarly characterized. As model compounds to assist in spectroscopic analysis, a series of related triazenes, the 1-(1-aryl-3-methyltriazen-3-yl)-N,N-dimethyl-2-ethanamines, were prepared by diazonium coupling with N,N,N'-trimethylethylenediamine. These dialkyltriazenes exist mainly as oils, but characterization was achieved by IR, 1H NMR, and 13C NMR spectroscopy, also showing the presence of two rotamers in solution when strongly electron-withdrawing substituents are bonded to the aryl moiety.Key words: triazene, bistriazene, diazonium, ethylenediamine, molecular dynamics, NMR.

Reaction of 6,11-dihydrodibenzo[b,e]thiepin-11-carbonitrile with 1,2-dibromoethane, a reinvestigation. Formation of 11,12-dihydro-6H-6,12-methanodibenzo[b,f]thiocin-12-carbonitrile

1987 ◽  
Vol 52 (9) ◽  
pp. 2281-2294 ◽  
Author(s):  
Karel Šindelář ◽  
Miloš Buděšínský ◽  
Tomáš Vaněk ◽  
Jiří Holubek ◽  
Emil Svátek ◽  
...  
Keyword(s):  
Tetrabutylammonium Bromide ◽  
Crystallographic Analysis ◽  
Preparative Hplc ◽  
Similar Reaction ◽  
X Ray ◽  
Cyanide Anion ◽  
Lithium Aluminium ◽  
The One ◽  
Benzyltriethylammonium Chloride ◽  
C Nmr

Reinvestigation of the minor product of reaction of 6,11-dihydrodibenzo[b,e]thiepin-11-carbonitrile (I) with 1,2-dibromoethane in the presence of tetrabutylammonium bromide or benzyltriethylammonium chloride and 50% sodium hydroxide by means of 1H and 13C NMR spectroscopy led to the formula XI named in the title, which was confirmed by X-ray crystallographic analysis. The product of a similar reaction, carried out in dimethyl sulfoxide in the presence of potassium carbonate at 100 °C was identified as the stereoisomeric mixture of 11,11'-ethylenebis(6,11-dihydrodibenzo[b,e]thiepin-11-carbonitriles) (XII) which was separated to the components by preparative HPLC. The title compound XI was oxidized to the sulfoxide XIII and the sulfone XIV, and was transformed by reduction and the following methylation to amines XV and XVI. The reduction of the vinyl nitrile III with lithium aluminium hydride is complicated on the one hand by allylic rearrangement, and with cyanide anion abstraction on the other, the products being (E,Z)-mixture of 3-(6,11-dihydrodibenzo[b,e]thiepin-11-ylidene)propylamines (XVII) and 11-vinyl-6,11-dihydrodibenzo[b,e]thiepin (X). The amine XVI is devoid of thymoleptic activity.

Reaktion von Imidodiphosphorsäuretetraphenylester mit Quecksilber(II)-oxid und Phenylquecksilberhydroxid / Reaction of Imidodiphosphoric Tetraphenylester with Mercury (II) Oxide and Phenylmercuryhydroxide

1980 ◽  
Vol 35 (5) ◽  
pp. 578-583 ◽  
Author(s):  
Horst Richter ◽  
Ekkehard Fluck ◽  
Wolfgang Schwarz
Keyword(s):  
Reaction Mechanism ◽  
Structural Data ◽  
Ring System ◽  
Membered Ring ◽  
X Ray ◽  
System 1

Abstract Reaction of imidodiphosphoric tetraphenylester with HgO yields the twelve-membered ring system 1, the properties, NMR and X-ray structural data of which are reported. A reaction mechanism is suggested. Reaction product from imidodiphosphoric tetraphenyl-ester and C6H5HgOH is N-phenylmercury-bis(phosphoric diphenylester)-imide (2).

Synthesis and X-ray powder diffraction data of cis-4-(4-methoxyphenyl)-3-methyl-6-nitro-2-phenyl-1,2,3,4-tetrahydroquinoline

2013 ◽  
Vol 28 (4) ◽  
pp. 307-311 ◽  
Author(s):  
M.A. Macías ◽  
J.A. Henao ◽  
Arnold R. Romero Bohórquez ◽  
Vladimir V. Kouznetsov
Keyword(s):  
Powder Diffraction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Gas Chromatography Mass Spectrometry ◽  
One Pot ◽  
X Ray ◽  
Cell Parameters ◽  
Diels Alder Reaction ◽  
The One ◽  
C Nmr

The 2,4-diaryl 1,2,3,4-tetrahydroquinoline derivative (1), described in the title (Chemical formula: C23H22N2O3), was synthesized via the “one-pot” three-component imino Diels–Alder reaction catalyzed by Cu(OTf)2. Molecular characterization was performed by 1H and 13C NMR, Fourier transform-infrared, and gas chromatography-mass spectrometry. The X-ray powder diffraction pattern for the title compound was analyzed and found to be crystallized in an orthorhombic system with space group P212121 (No. 19) and refined unit-cell parameters a = 8.6415(8) Å, b = 12.679(2) Å, c = 17.601(2) Å, and V = 1928.4(2) Å3.

X-Ray Structure Analysis and NMR Study of Sesquiterpene Lactone Hirsutolide

1995 ◽  
Vol 60 (2) ◽  
pp. 300-310 ◽  
Author(s):  
Urszula Rychłewska ◽  
Miloš Buděšínský ◽  
Halina Grabarczyk ◽  
Bohdan Drożdż ◽  
Miroslav Holub
Keyword(s):  
Crystal Structure ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Ring Conformation ◽  
X Ray ◽  
H Nmr ◽  
Nmr Study ◽  
Nmr Methods ◽  
The One ◽  
C Nmr

Hirsutolide, the C(8)-lactonized sesquiterpene of the heliangolide type has been studied by X-ray and NMR methods. In crystal the ten-membered ring conformation closely resembles the conformation observed in C(6)-lactonized heliangolides. This conformation, which can be described as a boat-chair is contrasted with the chair-chair conformation found in the crystals of other C(8)-lactonized heliangolide, scorpioidine. Broad signals in 1H and 13C NMR spectra indicated the conformation equilibrium in solution which was confirmed by observation of signals of two conformers (ca 3 : 1) in low temperature 1H NMR spectra. The major conformer is the one present in the crystal structure of hirsutolide and the minor conformer corresponds very likely to the one observed in the crystal structure of scorpioidine.

Structure in the solid state and conformational analysis in solution of 1,4-diacetyl-1,4-dihydro-2,3-diphenylpyrazine, a potential antiaromatic heterocyclic compound

1982 ◽  
Vol 60 (3) ◽  
pp. 349-354 ◽  
Author(s):  
Joseph Armand ◽  
Claudette Bois ◽  
Michèle Philoche-Levisalles ◽  
Marie-José Pouet ◽  
Marie-Paule Simonnin
Keyword(s):  
Solid State ◽  
Nitrogen Atom ◽  
Conformational Analysis ◽  
Nmr Spectra ◽  
Equilibrium Mixture ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nitrogen Bonds ◽  
Unambiguous Assignment ◽  
C Nmr

It is shown by X-ray crystallography that the 1,4-dihydropyrazine skeleton of 1,4-diacetyl-1,4-dihydro-2,3-diphenylpyrazine 2 has a boat shape. The C(2)–C(3) and C(5)–C(6) double bonds are localized; therefore 2 does not exist as an azahomoaromatic entity with 6 electrons delocalized on the ring and two electrons localized on one nitrogen atom. In the solid state 2 is in a Z, Z conformation. The 1H and 13C nmr spectra indicate that 2 exists as an equilibrium mixture of Z,E, E,E, and Z,Z conformers in CD2Cl2 at −80 °C. An unambiguous assignment of the different sets of signals has been obtained by nOe experiments performed at −80 °C. The conformer distribution is the following: 65% (Z,E), 22% (E,E), and 13% (Z,Z). The relatively low barrier to rotation about the carbonyl nitrogen bonds of the two amide groups [Formula: see text] is in line with a rather large C—N bond length (~1.375 Å) in the crystal.

Michael-Michael Aldol Reaction of Chalcones with Cyanoacetylurea and Cyanoacetylpiperidine

1995 ◽  
Vol 60 (4) ◽  
pp. 594-604 ◽  
Author(s):  
Hani D. Tabba ◽  
Nidal M. Yousef ◽  
Mohammad M. Al-Arab
Keyword(s):  
Room Temperature ◽  
Reaction Products ◽  
One Pot ◽  
X Ray ◽  
X Ray Crystallography ◽  
Anhydrous Alcohol ◽  
One Pot Condensation ◽  
The One ◽  
Sodium Alkoxide ◽  
C Nmr

Several highly substituted cyclohexane derivatives were synthesized by the one-pot condensation of chalcones and cyanoacetylurea (2 : 1) using sodium alkoxide in anhydrous alcohol at room temperature. The structure of the reaction products was established by infrared, 1H and 13C NMR spectroscopy as well as by their elemental analysis. Single crystal X-ray crystallography shows the presence of the cyclohexane moiety.

Nondestructive Inspection of Thin, Low-Z Samples using Multiplexed Compton Scatter Tomography

1997 ◽  
Vol 503 ◽  
Author(s):  
B. L. Evans ◽  
J. B. Martin ◽  
L. W. Burggraf
Keyword(s):  
Signal To Noise Ratio ◽  
Reconstruction Algorithm ◽  
Filtered Backprojection ◽  
Line Broadening ◽  
Compton Scatter ◽  
X Ray ◽  
Tomography System ◽  
Transmission Computed Tomography ◽  
High Purity Germanium ◽  
Scattered Energy

ABSTRACTThe viability of a Compton scattering tomography system for nondestructively inspecting thin, low Z samples for corrosion is examined. This technique differs from conventional x-ray backscatter NDI because it does not rely on narrow collimation of source and detectors to examine small volumes in the sample. Instead, photons of a single energy are backscattered from the sample and their scattered energy spectra are measured at multiple detector locations, and these spectra are then used to reconstruct an image of the object. This multiplexed Compton scatter tomography technique interrogates multiple volume elements simultaneously. Thin samples less than 1 cm thick and made of low Z materials are best imaged with gamma rays at or below 100 keV energy. At this energy, Compton line broadening becomes an important resolution limitation. An analytical model has been developed to simulate the signals collected in a demonstration system consisting of an array of planar high-purity germanium detectors. A technique for deconvolving the effects of Compton broadening and detector energy resolution from signals with additive noise is also presented. A filtered backprojection image reconstruction algorithm with similarities to that used in conventional transmission computed tomography is developed. A simulation of a 360–degree inspection gives distortion-free results. In a simulation of a single-sided inspection, a 5 mm × 5 mm corrosion flaw with 50% density is readily identified in 1-cm thick aluminum phantom when the signal to noise ratio in the data exceeds 28.

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