L. B. Volodarsky

Route to stable nitroxides with alkoxy groups at α- carbon - the derivatives of 2- and 3-imidazolines

Abstract Oxidation of 1-hydroxy-5,5-dimethyl-3-imidazoline-3-oxides containing one or two hydrogen atoms in position 2 of the heterocycle with lead dioxide in alcohol leads to stable nitroxides with alkoxy groups at α-carbon, the derivatives of 2- and 3-imidazolines, via the intermediate formation of 4H-imidazol-1,3-dioxides.

Stable nitroxyl radicals with a hydrogen atom at α-carbon atom of nitroxyl group

Nitroxyl radicals containing the diphenylmethyl group as one of the substituents at the nitroxyl group are stable compounds that can be isolated in an individual state.N-(2-Hydroxy-3-methyl-2-phenylcyclohexyl)-N-diphenylmethylnitroxyl was characterized by X-ray diffraction analysis for the first time.

Synthesis of stable nitroxides with amino groups and fluorine atoms at α-carbon of the radical centre

Abstract 2- and 3-Imidazoline nitroxides with amino groups in the position α to the radical centre are formed on oxidation of 4H-imidazole mono- and di-N-oxides in ethanolic solutions of NH 3 and CH 3 NH 2 . α-Fluorinated imidazolidine nitroxides have been obtained from 3-imidazoline-3-oxide derivatives by treatment with XeF 2 in CH 2 Cl 2 . Nucleophilic substitution of the fluorine atom resulted in formation of aminoimidazolidine nitroxides.

Nitration of imidazoline-N-oxide nitroxides containing the aryl nitrone group

Abstract Nitration of 4-aryl-3-imidazoline-3-oxide nitroxyl radicals leads to 4-nitroaryl-3-imidazoline-3-oxide nitroxides via oxammonium salts formation, the nitrone group being an ortho-para orientant.

Synthesis and properties ofN-[1-hydroxyimino-2-methyl-1-(2-pyridyl)prop-2-yl]hydroxylamine and heterocyclic derivatives based on it

N-[1-Hydroxyimino-2-methyl-1-(2-pyridyl)prop-2-yl]hydroxylamine, a new representative of the series of α-hydroxylamino oximes, was synthesized. Based on this compounds, 3-imidazoline 3-oxide and 2-imidazoline 3-oxide derivatives, were obtained, and some of their chemical properties were investigated.

Ammounium acetate as a catalyst of the condensation of sterically hindered functionalized hydroxylamines with ketones

Ammonium acetate was found to be a catalyst of the condensation of α-hydroxylamino oximes and α-hydroxylamino alcohols with ketones. This condensation leads to sterically hindered heterocyclic hydroxylamines, which are precursors of stable nitroxides.

Synthesis and oxidation of 1-hydroxy-3(2)-imidazoline-derived enaminones

Interaction of 1-hydroxy-3-imidazoline and 3-imidazoline 3-oxide derivatives with esters in the presence of LDA gives enaminones, derivatives of imidazolidine. Oxidation of these compounds with MnO2 leads to4H-imidazoleN-oxides, oxidative dirnerization products, or stable nitroxyl radicals, depending on the structure of the initial compound.

Regio- and stereoselectivity of 1,3-dipolar cycloaddition of cyclic aldonitrones of the 3-imidazoline 3-oxide series to monosubstituted alkenes

Regio- and stereoselectivity of 1,3-dipolar cycloaddition of cyclic aldonitrones of the 3-imidazoline 3-oxide series mainly depends on the type of the substituent in the dipolarophile. The configuration of the main cycloadduct has been determined, and a method has been suggested to establish the stereochemistry of the cycloaddition products by1H NMR spectroscopy. An increase in electron-acceptor properties of the substituent in the alkene molecule results in a decrease in the regio- and stereoselectivity of the cycloaddition.

Influence ofE/Z isomerism of aldoximes on the direction of their alkylation with oxirane

The reaction ofZ-2-furaldoxime with oxirane afforded theN-alkylation product,viz., α-2-furyl-N-(2-hydroxyethyl)nitron, in good yield.E-Benzaldoxime gave predominantly theO-alkylation product, while itsZ isomer was converted into a mixture with theN-alkylation product slightly predominating.

Synthesis of 1,2-bis(methoxyamino)cycloalkanes from alicyclic 1,2-bis(hydroxyamines)

Derivatives of 1,4-dihydroxypiperazine-2,3-dione were obtained by reaction of cis-1,2-bis(hydroxyamino)cycloalkanes with diethyl oxalate. Their alkylation with CH2N2 or Mel afforded 1,4-dimethoxypiperazine-2,3-diones. Hydrolysis of the latter gave 1,2-bis(methoxyamino)cycloalkanes.