Reactions of metallated 1-hydroxy-2,2,4,5,5-pentamethyl-3-imidazoline with electrophiles

Reactions of metallated 1-hydroxy-2,2,4,5,5-pentamethyl-3-imidazoline with electrophilic reagents followed by oxidation result in mono- and bifunctional substituted nitroxides of 3-imidazoline and an imidazolidine series including enaminocarbonyl and -thiocarbonyi derivatives and enaminoimines, the spin-labeled chelating reagents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1612–1616, September, 1993.     

Reactions of metallated 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole with functionalized nitroxyl radicals derived from 2,5-dihydro-1H-imidazole and 2,5-dihydro-1H-imidazole 3-oxide

The reactions of the dianion generated from 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole under the action of lithium diisopropylamide with nitroxyl radicals derived from 2,5-dihydro-1H-imidazole or 2,5-dihydro-1H-imidazole 3-oxide and containing the ester, aldehydo, cyano, or imino groups afforded biradicals, including those containing the enamino ketone and enamino imine functions. The reactions of this dianion with nitriles derived from 2,5-dihydro-1H-imidazole 3-oxide gave rise to an enamino nitrile, i.e., electrophilic cyanation formally occurred.     

Preparation of 1-hydroxy-2,2,4,6,6-pentamethyl-1,2,5,6-tetrahydropyrimidine 3-oxide and its nitroxyl radical

Conclusions The oxidation of N-(4-hydroxyimino-2-methyl-2-pentyl)-N-isopropylhydroxylamine gives 1-hydroxy-2,2, 4,6,6-pentamethyl-l,2,5,6-tetrahydropyrimidine 3-oxide, from which was generated the nitroxyl radical, namely 2,2,4,6,6-pentamethyl-1,2,5,6-tetrahydropyrimidine-1-oxyl 3-oxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2619–2622, November, 1977.     

Behavior of 1-hydroxy-2,2,5,5-tetramethyl-3-imidazoline-3-oxide and the corresponding nitroxyl radicals in superacid media

The protonation of 1-R-2,2,5,5-tetramethyl-3-imidazoline-3-oxides (R=OH, O) in superacid media was investigated with¹H and¹³C NMR. The hydroxylamino dication forming on protonation can undergo imidazoline ring opening to form an isomeric mixture of diprotonated N-(2-hydroxyimino-1,1-dimethylethyl),,-dimethylnitrones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2755–2761, December, 1991.     

Preparation of α-aminonitrones from 3-imidazoline-3-oxide α-methoxynitrones

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, p. 1944, August, 1988.     

Reactions of heterocyclic paramagnetic aldonitrone, 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxide, with alkynes

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. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 112–117, January, 2000.     

Reactions of heterocyclic paramagnetic aldonitrone, 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxide, with alkynes

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. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 112–117, January, 2000.     

Synthesis and properties of the first representatives of terminal acetylenes in 3-imidazoline-1-oxyl 3-oxide series

Method for the synthesis of m-and p-isomers of 4-[2-(ethynylphenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides by the cross-coupling of 4-[2-(3-iodophenyl)vinyl]-and 4-[2-(4-iodophenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl 3-oxides with (trimethylsilyl)acetylene followed by desilylation was elaborated. The reactions at the CH-fragment of the ethynyl group were performed. The Mannich reaction proceeds with the loss of a spin label, whereas the oxidative homocoupling, with its retention. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2051–2054, October, 2007.     

Reaction of amides of 3-imidazoline and 3-imidazoline-3-oxide derivatives with sodium hypobromite

Conclusions The reaction of 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl-4-carboxamide with sodium hypobromite leads to 4-amino-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl. 2,2,5,5-Tetramethyl-3-imidazoline-3-oxide-1-oxyl-4-carboxamide under the same conditions gives 3-hydroxy-2,2,5,5-tetramethylimidazolidin-4-one-1-oxyl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 228–231, January, 1979.     

Recyclization of α-hydroximino-β-oxo-3-imidazoline and 3-imidazoline-3-oxide derivatives to pyrrolines

Reaction of -hydroximino--oxo-3-imidazoline and 3-imidazoline-3-oxide derivatives with hydroxylamine results in recyclization leading to the formation of pyrroline derivatives, namely dioxines or nitrosooximes. Oxidation of dioximinopyrroline gives a pyrrolofuroxane.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1195–1198, September, 1990.     

Effect of the conditions of the formation of the crystalline phase of 1-hydroxy-5,5-dimethyl-2,4-diphenyl-3-imidazoline-3-oxide on the direction of its reaction with phenyllithium

The course of the heterogeneous reaction of 1-hydroxy-5,5-dimethyl-2,4-diphenyl-3-imidazoline 3-oxide with PhLi is dependent on the conditions of the formation of the crystalline phase of the starting compound. This compound can be isolated mainly in the cyclic or in the chain tautomeric forms.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1175–1176, June, 1995.     

The Mitsunobu 1-O-esterification of 1-hydroxy-3-phenyl-1H-quinoxalin-2-one 4-oxide

1-Hydroxy-2-oxo-3-phenyl-1,2-dihydroquinoxaline 4-oxide under conditions of the Mitsunobu reaction reacts with alcohols giving the corresponding esters at the hydroxy group in position 1. Other representatives of hydroxamic acids such as 1,4-dihydroxyperhydroquinoxaline-2,3-dione and 1,4-dihydroxy-3,3,6,6-tetramethylpiperazine-2,5-dione undergo destruction under these conditions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1240–1243, June, 2008.     

Cross-coupling of aryl iodides with paramagnetic terminal acetylenes derived from 4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide

2-(Arylylethynylphenyl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxides 12 and 13 were synthesized by cross-coupling of aryl iodides with 1-alkynes containing the 4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide fragment. A procedure was developed for the preparation of 3- and 4-ethynylbenzaldehydes with the use of 2-methylbut-3-yn-2-ol.