A novel crown ether generation containing the pyrilium heteroaromatic cation — Synthesis, characterization, and solid-phase 13C NMR

2004 ◽  
Vol 82 (12) ◽  
pp. 1716-1724 ◽  
Author(s):  
Abolghasem Moghimi ◽  
Majid Faal Rastegar ◽  
Mehdi Ghandi
Keyword(s):  
Crown Ether ◽  
Crown Ethers ◽  
Structural Characterization ◽  
Solid Phase ◽  
Condensation Reaction ◽  
Nmr Studies ◽  
Electrospray Mass Spectroscopy ◽  
Phenyl Rings ◽  
Heteroaromatic Cation ◽  
C Nmr

The synthesis and structural characterization of two members, 5 and 6, of a novel generation of crown ethers containing the pyrilium cation are reported. These two compounds contain two and three benzo-9-crown-3 (B9C3) units, respectively, connected to the 2 and 6 or 2, 4, and 6 positions of a central pyrilium cation. The crown ethers 5 and 6 were obtained from the condensation reaction of appropriate aldehydes and methyl ketones in the presence of POCl3. A variety of physicochemical methods including electrospray mass spectroscopy, solution 1H and 13C NMR, and solid-phase 13C NMR were applied for structural characterization. The 1H and 13C NMR studies indicate rapid rotation of the B9C3 unit about the C–C bond that connects the two units to each other. The solid-phase 13C NMR spectra of these two crown ethers reveal that there are deviations from planarity for the two phenyl rings attached at the 2 and 6 positions of the central pyrilium cation.Key words: crown ether, pyrilium, solid-phase NMR, crownpyrilium, heteroaromatic.

scholarly journals Novel O-C-C-O and C-O-C-C stereochemistry in crown ether analogs. X-ray crystal structure and NMR studies of dibenzo-20-crown-6

1995 ◽  
Vol 73 (1) ◽  
pp. 100-105 ◽  
Author(s):  
G.W. Buchanan ◽  
A. Moghimi ◽  
C. Bensimon
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
Crown Ethers ◽  
Nmr Studies ◽  
Trans Conformation ◽  
Torsion Angles ◽  
X Ray ◽  
Solid State Conformation ◽  
C Nmr

The X-ray crystal structure of the title material indicates that the molecule possesses a pseudo-centre of inversion. A pair of O-C-C-O bonds have a trans conformation in contrast to normal gauche stereochemistry for such units in crown ethers. For the C-O-C-C networks, which are normally transoid in crown ethers, all four such units involving methylene carbons of the 20-membered ring exhibit unusual geometries. Two units possess gauche conformations and the other two have torsion angles near 120°. Solution 1H and 13C NMR spectra have been recorded as a function of temperature and 13C solid state spectra are included. Keywords: crown ether, solid state conformation.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G W Buchanan ◽  
A B Driega ◽  
G PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
13C Nmr ◽  
Title Complex ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Large Amplitude Motion ◽  
C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS comple× of 1,4,7,11-tetrao×acyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G.W. Buchanan ◽  
A.B. Driega ◽  
G.P.A. Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ethers ◽  
Nmr Studies ◽  
X Ray ◽  
C Nmr

An example of conformational disorder in solids: X-ray crystallographic and 13C CPMAS NMR studies of dibenzo and dicyclohexano-13-crown-4 ethers and some lithium complexes

1990 ◽  
Vol 68 (1) ◽  
pp. 49-58 ◽  
Author(s):  
G. W. Buchanan ◽  
R. A. Kirby ◽  
J. P. Charland
Keyword(s):  
Crystal Structure ◽  
Crown Ethers ◽  
Nmr Spectra ◽  
Solid Phase ◽  
Nmr Studies ◽  
13C Cpmas Nmr ◽  
Conformational Disorder ◽  
X Ray ◽  
Lithium Complexes ◽  
Cis Isomer

For the cis–anti–cis isomer of dicyclohexano-13-crown-4 ether, disorder has been detected in the crystal structure, with two conformations being present in the ratio of ca. 3:2. Crystal structures for two Li+ complexes of the cis–syn–cis isomer have also been determined. Representative 13C solid phase NMR spectra are presented and discussed for these systems and the related dibenzo substituted compounds. Keywords: crown ethers, solids, NMR, conformation.

Benzo-9-crown-3 ether: X-ray crystal structure, NMR studies in solution and the solid phase, and ab initio calculations of isotropic 13C chemical shifts using LORG with a D95V basis set

1993 ◽  
Vol 71 (12) ◽  
pp. 1983-1989 ◽  
Author(s):  
G.W. Buchanan ◽  
A.B. Driega ◽  
A. Moghimi ◽  
C. Bensimon ◽  
R.A. Kirby ◽  
...  
Keyword(s):  
Ab Initio ◽  
Solid Phase ◽  
Chemical Shifts ◽  
Basis Set ◽  
Length Variation ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Localized Orbital ◽  
C Nmr

Using the X-ray crystal geometry as input, the 13C NMR chemical shifts of benzo-9-crown-3 ether have been calculated via ab initio methods using a localized orbital local origin (LORG) approach. Reasonable agreement is found between the calculated values for an isolated molecule in the gas phase and those obtained in the 13C CPMAS NMR spectrum. Solid phase 13C spectra of the C7,10-d4 derivative confirm the existence of a 7.9 ppm shift difference between these sites in the solid, whereas in solution they are conformationally averaged to one resonance. The effects of C—H bond length variation on calculated 13C shifts have been explored.

Electronic effects on crown ether conformation. X-ray crystal structure and 13C NMR study in solution and the solid phase of 4-nitrobenzo-9-crown-3 ether

1994 ◽  
Vol 72 (8) ◽  
pp. 1764-1768 ◽  
Author(s):  
G. W. Buchanan ◽  
A. B. Driega ◽  
A. Moghimi ◽  
C. Bensimon
Keyword(s):  
Crystal Structure ◽  
Crown Ether ◽  
13C Nmr ◽  
Solid Phase ◽  
Electronic Effects ◽  
Nmr Spectrum ◽  
X Ray ◽  
Nmr Study ◽  
C Nmr

The X-ray crystal structure of the title material has been determined and the results are compared to previous findings for benzo-9-crown-3 itself. The 13C NMR spectrum in solution has been unambiguously assigned using COSY and HETCOR methods. The solid phase 13C spectrum has been obtained and the 7, 10-d4 derivative has been examined to aid in spectral assignments.

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

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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