- A STABLE NITROXIDE - 2,2,5,5-TETRAMETHYL-3-IMIDAZOLINE-3-OXIDE-1-OXYL - A REAGENT FOR SPIN LABELING VIA 1,3-DIPOLAR CYCLOADDITION
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The paramagnetic heterocyclic aldonitrone, 2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl, reacts with C=C and C=N containing dipolarophiles to yield cycloadducts with radical centres.
- Volodarsky, L. B.,Martin, V. V.,Leluch, T. F.
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- Improved synthesis of 1-hydroxy-2,2,5,5-tetramethyl-3-imidazoline 3-oxide (HTIO)
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A simple, efficient, mild, and reproducible method for the synthesis of 1-hydroxy-2,2,5,5-tetramethyl-3-imidazoline 3-oxide is described. The method is based on the condensation of 2-hydroxyamino-2-methylpropanal oxime with 2,2-diethoxypropane in the presence of an equimolar quantity of acetic acid. Costeffectiveness of the condensation procedure could be also achieved by replacing 2,2-diethoxypropane with less expensive 2,2-dimethoxypropane. Copyright Taylor & Francis Group, LLC.
- Polienko, Julya F.,Schanding, Thomas,Voinov, Maxim A.,Grigor'ev, Igor A.
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- Reaction of Paramagnetic Synthon, Lithiated 4,4,5,5-Tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide, with Cyclic Aldonitrones of the Imidazole Series
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It was shown that dipole-stabilized paramagnetic carbanion lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide can be attached in a nucleophilic manner to either isolated or conjugated aldonitrones of the 2,5-dihydroimidazole 3-oxide and 2H-imidazole 1-oxide series to afford adducts the subsequent oxidation of which leads to polyfunctional mono- and diradicals. According to XRD, at least two polymorphic modifications can be formed during crystallization of the resulting paramagnetic compounds, and for each of them, geometric parameters of the molecules are similar. An EPR spectrum of the diradical in frozen toluene has a complicated lineshape, which can be fairly well reproduced by using X-ray diffraction structural analysis and the following set of parameters: D=14.9 mT, E=1.7 mT; tensor a(14N)=[0.260 0.260 1.625] mT, two equivalent tensors for the nitronyl nitroxide moiety a(14N)=[0.198 0.198 0.700] mT, and g≈2.007. According to our DFT and ab initio calculations, the intramolecular exchange in the diradical is very weak and most likely ferromagnetic.
- Tolstikov, Svyatoslav E.,Tretyakov, Evgeny V.,Gorbunov, Dmitry E.,Zhurko, Irina F.,Fedin, Matvey V.,Romanenko, Galina V.,Bogomyakov, Artem S.,Gritsan, Nina P.,Mazhukin, Dmitry G.
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- Reactions of heterocyclic paramagnetic aldonitrone, 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxide, with alkynes
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The reactions of heterocyclic paramagnetic aldonitrone, viz., 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxide, with mono- and disubstituted alkynes afford unstable isoxazoline derivatives. The reactions with monosubstituted alkynes yield predominantly 5-substituted regioisomers. The resulting isoxazoline derivatives are readily (and often spontaneously) converted into enaminoketones, viz., imidazolidine-1-oxyl derivatives. In the presence of tolan, the title paramagnetic aldonitrone gives a dimer in which one imidazoline ring undergoes profound transformation. The structure of the resulting dimer was established by X-ray diffraction analysis.
- Berezina,Reznikov,Volodarsky,Bagryanskaya,Gatilov
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p. 116 - 121
(2007/10/03)
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