scholarly journals Solid-state tautomeric structure and invariom refinement of a novel and potent HIV integrase inhibitor

2013 ◽  
Vol 69 (3) ◽  
pp. 285-288 ◽  
Author(s):  
John Bacsa ◽  
Maurice Okello ◽  
Pankaj Singh ◽  
Vasu Nair
Keyword(s):  
Solid State ◽  
Integrase Inhibitor ◽  
Correlation Spectroscopy ◽  
Hiv Integrase ◽  
Acta Cryst ◽  
X Ray ◽  
X Ray Crystallography ◽  
Molecular Charge ◽  
Intramolecular Hydrogen ◽  
C Nmr

The conformation and tautomeric structure of (Z)-4-[5-(2,6-difluorobenzyl)-1-(2-fluorobenzyl)-2-oxo-1,2-dihydropyridin-3-yl]-4-hydroxy-2-oxo-N-(2-oxopyrrolidin-1-yl)but-3-enamide, C27H22F3N3O5, in the solid state has been resolved by single-crystal X-ray crystallography. The electron distribution in the molecule was evaluated by refinements with invarioms, aspherical scattering factors by the method of Dittrichet al.[Acta Cryst.(2005), A61, 314–320] that are based on the Hansen–Coppens multipole model [Hansen & Coppens (1978).Acta Cryst.A34, 909–921]. The β-diketo portion of the molecule exists in the enol form. The enol –OH hydrogen forms a strong asymmetric hydrogen bond with the carbonyl O atom on the β-C atom of the chain. Weak intramolecular hydrogen bonds exist between the weakly acidic α-CH hydrogen of the keto–enol group and the pyridinone carbonyl O atom, and also between the hydrazine N—H group and the carbonyl group in the β-position from the hydrazine N—H group. The electrostatic properties of the molecule were derived from the molecular charge density. The molecule is in a lengthened conformation and the rings of the two benzyl groups are nearly orthogonal. Results from a high-field1H and13C NMR correlation spectroscopy study confirm that the same tautomer exists in solution as in the solid state.

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

The relative stabilities of PhE(NH-t-Bu)2 and PhE(μ-N-t-Bu)2EPh (E = As, Sb, and Bi): X-ray structures of {Li2[PhAs(N-t-Bu)2]}2 and PhE(μ-N-t-Bu)2EPh (E = Sb, Bi)

2003 ◽  
Vol 81 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Glen G Briand ◽  
Tristram Chivers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Phenyl Group ◽  
Synthetic Approach ◽  
Relative Stabilities ◽  
X Ray ◽  
X Ray Crystallography ◽  
In Trans ◽  
C Nmr

The reaction of PhECl2 with 2 equiv of LiHN-t-Bu has been studied for the series E = As, Sb, and Bi to determine the effect of the phenyl group on subsequent amine condensation processes. For PhAsCl2, the metathesis product PhAs(NH-t-Bu)2 4 was obtained as a colourless oil. Similar reactions involving PhECl2, where E = Sb or Bi, yielded the cyclodipnict(III)azanes PhE(μ-N-t-Bu)2EPh 5 (E = Sb) and 6 (E = Bi), respectively. Treatment of 4 with 2 equiv of n-BuLi produced the dilithium salt Li2[PhAs(N-t-Bu)2] 7a. Products 4, 5, 6, and 7a were characterized by 1H, 7Li (7a), and 13C NMR spectra, while 5, 6, and 7a were also structurally characterized by X-ray crystallography. Compound 7a is dimeric in the solid state via intermolecular Li···N and η6-Li···Ph interactions. The cyclodipnict(III)azanes 5 and 6 have similar structures, with the exocyclic phenyl groups in trans positions relative to the E2N2 ring. This synthetic approach provides a new route to the four-membered rings RE(μ-N-t-Bu)2ER (E = Sb, Bi) and the first example of a bis(organyl)cyclodibism(III)azane.Key words: arsenic, antimony, bismuth, amides, imides.

Two-bond 13C–13C spin-coupling constants in saccharides: dependencies on exocyclic hydroxyl group conformation

2021 ◽  
Author(s):  
Jieye Lin ◽  
Reagan J. Meredith ◽  
Allen G. Oliver ◽  
Ian Carmichael ◽  
Anthony S. Serianni
Keyword(s):  
Solid State ◽  
Torsion Angle ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Spin Coupling Constants ◽  
C Nmr

13C-Labeled mono- and disaccharides were studied by X-ray crystallography and solid-state 13C NMR to determine the dependence of 2JC1,C3 in aldopyranosyl rings on the C1–C2–O2–H torsion angle, θ2, involving C2 of the C1–C2–C3 coupling pathway.

Crystal Structure and Conformation of 2-{(2′-Aminobenzyl)iminoethyl}- 5-methoxyphenol

2001 ◽  
Vol 56 (4-5) ◽  
pp. 375-380 ◽  
Author(s):  
D. K. Dey ◽  
S. P. Dey ◽  
A. Elmali ◽  
Y. Elerman
Keyword(s):  
Molecular Structure ◽  
Minimum Energy ◽  
Intramolecular Hydrogen Bonding ◽  
Stable Conformation ◽  
Torsion Angles ◽  
Triclinic Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Intramolecular Hydrogen ◽  
C Nmr

AbstractThe Schiff base, 2-{(2′-aminobenzyl)iminoethyl}-5-methoxyphenol, 1,2 -C6H4[NH2-2 ʹ]-CH2N=CHC6H3(OMe-5)OH (I), has been prepared by the reaction of 2 -amino-1-benzylamine and 2-hydroxy-4-methoxyacetophenone in methanol. The molecular structure has been con­firmed by single crystal X-ray crystallography (triclinic, space group P 1̄, a = 7.201(2), b = 9.802(2), c = 9.993(2) Å, α = 83.09(2), β = 73.49(2), γ = 84.09(2)°, R = 0.0415 for 2611 independent reflections). The 1H and 13C NMR spectra in CDCI3 solution indicate the forma­tion of some other minor conformations or dissociation in solution. The title compoundois not planar. Intramolecular hydrogen bonding occurs between O(1) and N(1) atoms [2.528(2) Å], the hydrogen atom essentially being bonded to the nitrogen atom. Minimum energy conformations from AMI were calculated as a function of four torsion angles. The optimized geometry of the molecular structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by non-bonded hydrogen-hydrogen repulsions.

A 3D Chiral Hydrogen Bond Framework Based on Phenanthrolinium Hydrogen 4,5-Dichlorophthalate: Crystal Structure and Luminescent Properties

2012 ◽  
Vol 67 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Bing An ◽  
Yan Bai ◽  
Fan Yang
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Uv Spectroscopy ◽  
Luminescent Properties ◽  
Aromatic Rings ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Face To Face ◽  
X Ray Crystallography ◽  
Intramolecular Hydrogen

A salt with the composition [C12H9N2][C8H3Cl2O4] (1) with 4,5-dichlorophthalic acid and 1,10- phenanthroline (phen) has been synthesized and characterized by IR, UV spectroscopy, elemental analysis, and X-ray crystallography. Compound 1 represents a 3D chiral supramolecular framework containing monohelical chains (21 axis) through multiform C-H· · ·O, O-H· · · O, N-H· · ·N intramolecular hydrogen bonds and C-H· · ·O, N-H· · ·O intermolecular hydrogen bonds. Otherwise, two types of face-to-face π · · ·π interactions between the aromatic rings are found in the solid state. The luminescent properties of compound 1 were investigated in the solid state at room temperature

A topochemical rearrangement with multiple inversions of configuration

2001 ◽  
Vol 79 (8) ◽  
pp. 1272-1277 ◽  
Author(s):  
Saul Wolfe ◽  
Yih-Huang Hsieh ◽  
Raymond J Batchelor ◽  
Frederick WB Einstein ◽  
Ian D Gay
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Room Temperature ◽  
The Other ◽  
X Ray ◽  
Controlled Processes ◽  
X Ray Crystallography ◽  
Intramolecular Process ◽  
C Nmr ◽  
The Ideal

Crystalline 2-benzyloxypyridine-1-oxide rearranges slowly at room temperature to crystalline 1-benzyloxy-2-pyridone. No intermediates are detected when the process is followed by solid-state 13C NMR. The crystal structure of the pyridine-1-oxide strongly suggests that a topochemically controlled intramolecular process, in which the benzyl group migrates with retention of configuration, is not feasible. On the other hand, although somewhat disfavoured by initial solid-state O···C···O angles significantly less than the ideal 180°, intermolecular topochemically controlled processes can be envisaged that lead, with multiple inversions of configuration, either to net retention of configuration or to net inversion of configuration in the benzyl group. In contrast to the 50–80% inversion observed in solution, in the solid state only inversion is observed experimentally when chirally labelled α-deuteriobenzyloxypyridine-1-oxide is allowed to rearrange.Key words: X-ray crystallography, solid-state 13C NMR, benzyl-α-D-alcohol, 2-benzyloxypyridine-1-oxide, 1-benzyloxy-2-pyridone.

scholarly journals The synthesis and X-ray structures of the geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid

1993 ◽  
Vol 71 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Kenneth Curry ◽  
Hugh McLennan ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Elevated Temperatures ◽  
Geometric Isomers ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Hydrolysis Of ◽  
Cis Isomer ◽  
C Nmr

The geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid were isolated as the hydrolysis products of 2-cyclopentanecarboxylic acid-5,5′-hydantoin. The hydantoin ester was formed from ethyl -2-oxocyclopentanecarboxylate via a Bucherer–Bergs reaction. Hydrolysis of the hydantoin at elevated temperatures gave a mixture of trans- and cis-1 -amino-1,2-cyclopentanedicarboxylic acids indicating epimerization during hydrolysis. The trans product has not been described previously and the cis not extensively characterized. X-ray crystallography reveals that both isomers are zwitterionic in the solid state and the cis isomer molecules are linked by unusually strong hydrogen bonding. Structures were confirmed by 13C NMR, X-ray crystallography, and elemental analysis. Physical data are also presented.

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.

Synthesis, characterization, and solid-state polymerization of cross-conjugated octatetraynes

2012 ◽  
Vol 90 (11) ◽  
pp. 994-1014 ◽  
Author(s):  
Yuming Zhao ◽  
Thanh Luu ◽  
Guy M. Bernard ◽  
Tyler Taerum ◽  
Robert McDonald ◽  
...  
Keyword(s):  
Solid State ◽  
Crystallographic Analysis ◽  
Scanning Calorimetry ◽  
X Ray ◽  
R And D ◽  
X Ray Crystallography ◽  
Topochemical Polymerization ◽  
Pendent Groups ◽  
C Nmr

Two series of cross-conjugated 1,3,5,7-octatetraynes (1a–1l and 6a–6d) have been synthesized. UV–vis spectroscopic analysis shows that pendent groups connected to the cross-conjugated skeleton have little effect on the λmax energies, irrespective of whether the groups are electron withdrawing or donating. A number of the isolated products readily give crystals suitable for X-ray crystallography, and the solid-state structural properties of five derivatives (1k, 1l, 6a, 6c, and 6d) have been examined by X-ray crystallographic analysis. Parallel packing of the polyynes in the solid state indicates that four of the five samples are potentially suitable for topochemical polymerization, based on solid-state packing parameters θ, R, and d. Attempts to effect a solid-state reaction have been explored through UV–vis and γ-ray irradiation as well as thermal heating. The course of these reactions was monitored by differential scanning calorimetry (DSC) analysis, as well as UV–vis and solid-state 13C NMR spectroscopy (for 1d, 1j, 1k, and 6d), which offered evidence of polymer formation from these reactions. Structural determination of the product(s), however, remains elusive.

Crystal and solution structure of (E)-1,2-bis(ethylsulphonyl)cyclobutane-1,2-dicarbonitrile

1989 ◽  
Vol 54 (12) ◽  
pp. 3253-3259
Author(s):  
Jaroslav Podlaha ◽  
Miloš Buděšínský ◽  
Jana Podlahová ◽  
Jindřich Hašek
Keyword(s):  
Hydrogen Peroxide ◽  
Solution Structure ◽  
Peroxide Oxidation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nmr Study ◽  
Hydrogen Peroxide Oxidation ◽  
Unusual Product ◽  
C Nmr

The unusual product of the reaction of 2-chloroacrylonitrile with ethane thiol and following hydrogen peroxide oxidation was found to be (E)-1,2-bis(ethylsulphonyl)cyclobutane-1,2-dicarbonitrile by means of X-ray crystallography. 1H and 13C NMR study of this compound has proven the same conformation of the molecule in solution.

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