First acetylenic derivatives of stable 3-imidazoline nitroxides

The Stephens-Castro reaction of copper(I) salts of 1-aryl(hetaryl)alkynes with 2,2,5,5-tetramethyl-4-[2-(4-iodophenyl)-vinyl]imidazoline-3-oxide-1-ol proved to be a general method for the preparation of 2,2,5,5-tetramethyl-4-[2-(p-aryl(hetaryl)ethynylphenyl)]vinyl-3-imidazoline-3-oxide-1-oxyles.     

Oxidative coupling of alkynes mediated by nitroxyl radicals under Sonogashira conditions and Pd-free catalytic approach to stable radicals of 3-imidazoline family with triple bonds

In the presence of Pd catalyst, 3-imidazoline nitroxyl radicals promote oxidative coupling (dimerization) of terminal alkynes even in the absence of Cu(II) additives. On the other hand, the Pd-free CuI-PPh₃-K₂CO₃-DMF catalytic system leads to the efficient cross-coupling of 1-hydroxy-4-[2-(p-iodophenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-3-oxide with terminal aryl- and hetarylacetylenes with the formation of 4-[2-(aryl/hetarylethynyl)phenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyls in 70-75% yields.     

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.     

Chemistry of iminofurans: IX. Synthesis and cyclization of (2<Emphasis Type="Italic">Z</Emphasis>)-2-{(2<Emphasis Type="Italic">Z</Emphasis>)-2-[2-(3-R-adamantan-1-yl)-2-oxoethylidene]hydrazinyl}-4-(het)aryl-4-oxobut-2-enoic acids

1-(3-R-adamantan-1-yl)-2-[(triphenyl-λ⁵-phosphanylidene)hydrazinylidene]ethanone reacted with 4-aryl(hetaryl)-2,4-dioxobutanoic acids to give 2-{2-[2-(3-R-adamantan-1-yl)-2-oxoethylidene]hydrazinyl}-4-aryl(hetaryl)-4-oxobut-2-enoic acids which were shown to exist in solution as mixtures of Z- and E-isomeric enehydrazine tautomers. The products underwent cyclization to 3-{[2-(3-R-adamantan-1-yl)-2-oxoethylidene]- hydrazinylidene}-5-aryl(hetaryl)furan-2(3H)-ones.     

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.     

Chemistry of iminofurans: X. Synthesis and hydrolysis of 5-aryl(hetaryl)-2-[(4,5,6,7-tetrahydro-1-benzothiophen-2-yl)imino]furan-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

5-Aryl(hetaryl)furan-2,3-diones reacted with N-(triphenyl-λ⁵-phosphanylidene)-4,5,6,7-tetrahydro-1-benzothiophen-2-amines to give 5-aryl(hetaryl)-2-[(4,5,6,7-tetrahydro-1-benzothiophen-2-yl)imino]furan-3(2H)-ones whose acid hydrolysis afforded 4-aryl(hetaryl)-2-hydroxy-4-oxo-N-(4,5,6,7-tetrahydro-1-benzothiophen- 2-yl)but-2-enamides.     

Plant coumarins: XI. Cross coupling reactions with 2-(tosyl)oreoselone

The reaction of a linearly fused furocoumarin, oreoselone, with p-toluenesulfonyl chloride gave 2-tosyloreoselone which showed a high reactivity in palladium-catalyzed cross-coupling reactions with formation of a new carbon-carbon bond. 2-Tosyloreoselone reacted with terminal alkynes in the presence of Pd(PPh₃)₂Cl₂ to give the corresponding 2-alkynylfuro[3,2-g]chromen-3-ones. 2-Aryl(hetaryl)alkynyloreoselones were obtained in high yield directly by palladium-catalyzed reaction of oreoselone with tosyl chloride and aryl(hetaryl)acetylenes. The reaction of 2-tosyloreoselone with aryl(hetaryl)boronic acids in the presence of palladium complexes with uni- and bidentate ligands, tetrabutylammonium bromide, and a base afforded 2-aryl(hetaryl)-substituted oreoselones. 2-Vinyloreoselone was synthesized from 2-tosyloreoselone and potassium trifluoro(vinyl)borate.     

Synthesis and reactions of 3-(3-ethoxycarbonyl-1-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-4-yl)propenic acid

The reaction of ethyl 4-formyl-1-phenyl-1H-pyrazole-3-carboxylate with the malonic acid led to the formation (2E)-3-(3-ethoxycarbonyl-1-phenyl-1H-pyrazol-4-yl)propenic acid. In reactions of this acid chloride with 4-amino-5-aryl(hetaryl)-4H-1,2,4-triazole-3-thiols were obtained ethyl 4-[(E)-2-{3-aryl(hetaryl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-yl}ethenyl]-1-phenyl-1H-pyrazoe-3-carboxylates, with 5-aryltetrazoles, ethyl 4-[(E)-2-(5-aryl-1,3,4-oxadiazol-2-yl)-ethenyl]-1-phenyl-1H-pyrazole-3-carboxylates, with 1-(2-hydroxy-3,5-dimethylphenyl) followed by the Baker-Venkataraman rearrangement and the cyclization, ethyl 4-[(E)-2-(6,8-dimethyl-4-oxo-4Hchromen-2-yl)ethenyl]-1-phenyl-1H-pyrazole-3-carboxylate.     

Synthesis and structure of aryl(hetaryl)spiropyrrolidones

Hydrogenation of the diastereouniform 3-[1-aryl(hetaryl)-2-nitroethyl]-3-methoxycarb-onyl-4-phenyl(3-pyridyl)-2-pyrrolidones is accompanied by intramolecular acylation of the formed amino group to afford the diastereomerically pure 4,4′-aryl(hetaryl)-3,3′-spirobi-[2-pyrrolidones]. The structures of these diastereomers were characterized by IR, ¹H and ¹³C NMR spectroscopy using heteronuclear correlation experiments, and X-ray diffraction study.     

Modulation effects in the electron spin echo of trans bis-(2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl-4-il) ethylene biradicals

Electron spin echo modulation effects have been investigated in trans bis(2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl-4-il) ethylene biradicals involving ¹⁴N or ¹⁵N nuclei in different positions. The modulation frequencies are shown to be the nitrogen nuclear transition frequencies in radical fragments at m_S = 0 of a triplet electronic spin. Quadrupole splitting parameters for these nitrogen nuclei have been determined.     

Synthesis of 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl

Condensation of -(hydroxylamino)-2-methylpropanal with acetone and ammonia afforded 2,2,5,5-tetramethyl-3-imidazoline-1-oxyl, the first member of a series of stable nitroxyl radicals which are derivatives of 3-imidazoline. It was shown that 2,2,5,5-tetramethyl-2, 5-dihydropyrazine-1,4-dioxide can reversibly add two molecules of water or ammonia to the nitrone groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 931–933, May, 1993.     

Study of plant coumarins: X. Peurutenicin triflate in cross-coupling reactions

By Suzuki cross-coupling reaction of peurutenicin triflate with arylboric, furanylboric, pyridinylboric, and indolylboric acids the corresponding 7-aryl(hetaryl)coumarins were synthesized. The high activity of hetaryl-substituted boric acids in the Suzuki reaction was observed. Heck reaction of 7-O-trifluoromethylsulfonylpeur utenicin with terminal olefins (styrene, vinylpyridines, vinylpyrazine, vinyltriazole) was used to prepare (E)-7-[aryl(hetaryl)vinyl]coumarins. The dependence of reaction products yield on the nature of the catalytic system was found.     

Dehydrogenation of 1-aryl(hetaryl)-1,2,3,4-tetrahydro-9<Emphasis Type="Italic">H</Emphasis>-β-carboline-3-carboxylic acids and their esters with dimethyl sulfoxide

Oxidative dehydrogenation of 1-aryl(hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylic acids derivatives with dimethyl sulfoxide leads to the formation of 1-aryl(hetaryl)-9Н-β-carbolines. Simultaneously with the dehydrogenation decarboxylation occurs. At the oxidation with dimethyl sulfoxide of methyl 1-aryl (hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylicates methyl 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylates formed whose hydrolysis afforded the corresponding 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylic acids.     

Synthesis and Structure of (2E)-3-Aryl(hetaryl)-2-[5-bromo-4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles

Russian Journal of General Chemistry - Bromination of (2E)-3-aryl(hetaryl)-2-[4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles proceeds regioselectively at the C5 atom of the thiazole ring with the...     

One-pot assembly of 4-methylene-3-oxa-1-azabicyclo[3.1.0]hexanes from alkyl aryl(hetaryl) ketoximes, acetylene, and aliphatic ketones: a new three-component reaction

A new three-component reaction between alkyl aryl(hetaryl)ketoximes, acetylene, and aliphatic ketones in the superbasic systems KOH/DMSO and LiOH/CsF/DMSO (70-90 °C, initial acetylene pressure 13-15 atm, 5-60 min) affords novel 4-methylene-3-oxa-1-azabicyclo[3.1.0]hexanes in yields of up to 75%. Using KOH/DMSO, the side products of the reaction are O-vinylketoximes and 2-aryl(hetaryl)pyrroles, while with LiOH/CsF/DMSO, the reaction proves to be selective, only minor amounts of the corresponding alkyl aryl(hetaryl) ketones being detectable.     

New Efficient Synthesis of Methyl Trans-2-Aryl (or Hetaryl)-1-Benzamidocyclopropancarboxylates

Methyl trans-2-aryl(or hetaryl)-1-benzamidocyclopropancarboxylates can be easily obtained by thermal decomposition of trans-4-aryl(or hetaryl)-3-benzamido-3-carbomethoxy-Δ¹-pyrazolines synthesized by 1,3-dipolar cycloaddition of diazomethane with methyl E-3-aryl(or hetaryl)-2-benzamido-2-propenoates.     

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.     

Oxidation of 1,3-Dioxacyclanes with Oxone and Potassium Persulfate Catalyzed by 2,2,5,5-Tetramethyl-4-Phenyl-3-Imidazoline-3-Oxide-1-Oxyl

The catalytic effect of 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl on the oxidation of 2-isopropyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 2-phenyl-4-chlormethyl-1,3-dioxolane, 2-isopropyl-1,3-dioxane, 2-isopropyl-4-methyl-1,3-dioxane, 2-phenyl-1,3-dioxane, 2-phenyl-4-methyl-1,3-dioxane with oxone and potassium persulfate is reported. The corresponding glycol monoesters were obtained with yields of 90-100%.     

Synthesis of methyl 7-aryl(hetaryl, cyclohexenyl)-10-(1,3-benzodioxol-5-yl)-8-oxo-7,8,9,10,11,12-hexahydro-benzo[b][1,7]phenanthroline-9-carboxylates

Three-component condensation of quinolin-5-amine with methyl 2-(1,3-benzodioxol-5-yl)-4,6-dioxocyclohexane-1-carboxylates and aromatic aldehydes (or cyclohex-3-ene-1-carbaldehyde) afforded new hexahydrobenzo[b][1,7]phenanthroline derivatives. The condensation in butan-1-ol is strictly regioselective but not stereoselective, so that mixtures of cis- and trans-isomeric methyl 7-aryl(hetaryl, cyclohexenyl)-10-(1,3-benzodioxol-5-yl)-8-oxo-7,8,9,10,11,12-hexahydrobenzo[b][1,7]phenanthroline-9-carboxylates at a ratio of ～40: 60% are formed.     

Syntheses and Study of a Pyrroline Nitroxide Condensed Phospholene Oxide and a Pyrroline Nitroxide Attached Diphenylphosphine

The reaction of a diene nitroxide precursor with dichlorophenylphosphine in a McCormac procedure afforded 1,1,3,3-tetramethyl-5-phenyl-1,2,3,4,5,6-hexahydrophospholo[3,4-c]pyrrole-5-oxide-2-oxyl. Lithiation of the protected 3-iodo-pyrroline nitroxide followed by treatment with chlorodiphenylphosphine after deprotection afforded (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine oxide, and after reduction, (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine was realized, which was also supported by X-ray single crystal diffraction measurements. This pyrroline diphenylphosphine derivative was converted to hexadecylphosphonium salt, which is an analogue of antineoplastic agent, MITO-CP.