scholarly journals Stereochemical rearrangements in tricarbonylrhenium(I) halide complexes of the nonracemic chiral ligand 2-[(4R,5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L): a dynamic NMR study

1999 ◽  
Vol 77 (11) ◽  
pp. 1707-1715 ◽  
Author(s):  
Peter J Heard ◽  
Alex D Bain ◽  
Paul Hazendonk
Keyword(s):  
Carbon Atom ◽  
Chiral Ligand ◽  
Dynamic Nmr ◽  
Free Energies ◽  
Ligand Dissociation ◽  
Nmr Study ◽  
Nmr Techniques ◽  
Halide Complexes ◽  
Acetal Ring ◽  
Acetal Carbon

Tricarbonylrhenium(I) halide complexes of the nonracemic chiral ligand 2-[(4R,5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L), namely fac-[ReX(CO)3L] (X = Cl, Br, or I), have been prepared and their latent fluxionality studied by dynamic NMR techniques in the slow and intermediate exchange regimes. In solution, these complexes give rise to four diastereoisomers, depending on the configuration at the metal and at the acetal-carbon atom, respectively; the relative populations are in the order SR > RR >>; RS > SS. At moderate temperatures, a reversible "acetal ring flip" leads to formal inversion of configuration at the acetal-carbon atom; the free energies of activation are in the range 84-88 kJ mol-1 at 298 K. Above ca. 370 K, reversible ligand dissociation also occurs, leading to an exchange of all four diastereoisomers on the NMR chemical shift time-scale.Key words: dynamic NMR, fluxionality, tricarbonylrhenium(I) complexes, chiral acetal ligands.

A dynamic NMR study of 1,2-metallotropic shifts in trimethylplatinum(IV) halide complexes fo 3-methylpyridazine

Polyhedron ◽  
1994 ◽  
Vol 13 (20) ◽  
pp. 2907-2913 ◽  
Author(s):  
Edward W. Abel ◽  
Peter J. Heard ◽  
Keith G. Orrell ◽  
Vladimir Šik
Keyword(s):  
Dynamic Nmr ◽  
Nmr Study ◽  
Halide Complexes

Novel tetracyclic imidazole derivatives: Synthesis, dynamic NMR study, and anti-inflammatory evaluation

2010 ◽  
pp. n/a-n/a
Author(s):  
Renata Rupčić ◽  
Marina Modrić ◽  
Antun Hutinec ◽  
Ana Čikoš ◽  
Barbara Stanić ◽  
...  
Keyword(s):  
Dynamic Nmr ◽  
Imidazole Derivatives ◽  
Nmr Study ◽  
Anti Inflammatory

Gas-Phase Dynamic NMR Study of the Internal Rotation inN-Trifluoroacetylpyrrolidine

2003 ◽  
Vol 107 (17) ◽  
pp. 3024-3029 ◽  
Author(s):  
Cristina Suarez ◽  
Elisabeth J. Nicholas ◽  
Molly R. Bowman
Keyword(s):  
Gas Phase ◽  
Internal Rotation ◽  
Dynamic Nmr ◽  
Phase Dynamic ◽  
Nmr Study

scholarly journals Evidence of the Existence of 2:1 Guest–Host Complexes between Diclofenac and Cyclodextrins in D2O Solutions. A 1H and 13C NMR Study on Diclofenac/β-Cyclodextrin and Diclofenac/2-Hydroxypropyl-β-cyclodextrin Systems

1999 ◽  
Vol 23 (7) ◽  
pp. 414-415
Author(s):  
Adele Mucci ◽  
Luisa Schenetti ◽  
Maria A. Vandelli ◽  
Barbara Ruozi ◽  
Flavio Forni
Keyword(s):  
13C Nmr ◽  
Sodium Salt ◽  
Multiple Equilibria ◽  
Diclofenac Sodium ◽  
1H And 13C Nmr ◽  
Nmr Study ◽  
Nmr Techniques ◽  
Nmr Titrations ◽  
C Nmr

The interaction of diclofenac sodium salt (DCFNa) and two cyclodextrins, β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HPβCD), studied in D2O solution with different NMR techniques (1H, 13C NMR, ROESY experiments, NMR titrations), shows the existence of multiple equilibria involving 1:1 and 2:1 guest–host complexes.

Exploring the potential of imines as antiprotozoan agents with focus on t. Brucei and p. Falciparum

2018 ◽  
Author(s):  
◽  
Kola Augustus Oluwafemi
Keyword(s):  
Hela Cell ◽  
Cell Line ◽  
Special Focus ◽  
Hela Cell Line ◽  
Free Energies ◽  
Imino Group ◽  
Design Synthesis ◽  
Lead Compounds ◽  
Pyridine Moiety ◽  
Nmr Study

This work focuses on the design, synthesis and evaluation of imine-containing heterocyclic and acyclic compounds with special focus on their bioactivity against parasitic protozoans (P. falciparum and T. brucei) - given the context of drug resistance in the treatment of malaria and Human African sleeping sickness and the fact that several bioactive organic compounds have been reported to possess the imino group. Starting from 2-aminopyridine, novel #-alkylated-5-bromo-7-azabenzimidazoles and substituted 5-bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives were prepared, and their bioactivity against parasitic protozoans was assessed. NMR spectra of the substituted 5- bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives exhibited rotational isomerism, and a dynamic NMR study was used in the estimation of the rate constants and the free- energies of activation for rotation. The free-energy differences between the two rotamers were determined and the more stable conformations were predicted. Novel 2-phenyl-7-azabenzimidazoles were also synthesised from 2-aminopyridine. A convenient method for the regioselective formylation of 2,3-diaminopyridines into 2-amino- 7-(benzylimino)pyridine analogues of 2-phenyl-7-azabenzimidazole was developed, and some of the resulting imino derivatives were hydrogenated to verify the importance of the imino moiety for bioactivity. The 2-phenyl-7-azabenzimidazoles and the 2-amino-7- (benzylimino)pyridine analogues were screened for their anti-protozoal activity and their cytotoxicity level was determined against the HeLa cell line. In order to validate the importance of the pyridine moiety, novel #-(phenyl)-2- hydroxybenzylimines, #-(benzyl)-2-hydroxybenzylimines and (±)-trans-1,2-bis[2- hydroxybenzylimino]cyclohexanes were also synthesized and screened for activity against the parasitic protozoans and for cytotoxicity against the HeLa cell line. The biological assay results indicated that these compounds are not significantly cytotoxic and a good number of them show potential as lead compounds for the development of new malaria and trypanosomiasis drugs.

Sign in / Sign up

Export Citation Format

Share Document