Synthesis and molecular and crystal structure of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan and its N-methyl and N,N′-dimethyl derivatives

3-(1-Amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (2) and its N-methyl and N,N′-dimethyl derivatives were synthesized by the reaction of perforo-1-ethylideneindan with ammonia and methylamine or by methylation of compound 2 with dimethylsulfate. Single crystals were grown and the molecular and crystal structure of the emaninoimine products was investigated. The density functional theory (DFT) quantum chemical calculations were performed to determine possible tautomeric equilibrium of the emaninoimine products.     

Stable vinylnitroxyl radicals, pyrroline derivatives

The first representatives of stable vinyl nitroxides,viz., radicals of the pyrroline series, were synthesized. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 103–111, January, 2000.     

Synthetic Transformations of Higher Terpenoids. 41. Synthesis and Anti-Inflammatory Activity of 4-(Carboxyalkyl)-18-nor-isopimara-7,15-Dienes

Chemistry of Natural Compounds - Synthetic methods were developed for isopimaric acid derivatives, the terminal carboxylic acid of which was separated by two or three methylenes from the tricyclic...     

Single crystal x-ray diffraction study of dioxane,pyrazine, and pyridine complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan

Single crystals of complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (1) with 1,4-dioxane, pyrazine, and pyridine have been synthesized. Their structure was investigated by X-ray analysis. In crystals of the dioxane complex, compound 1 is present together with its tautomer — 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1a), and these compounds are in an equilibrium ratio of ～60:40. Gas-phase quantum chemical calculations have been performed to examine the possibility of a tautomeric equilibrium of enaminoimine 1 in the corresponding complexes.     

Synthetic transformations of sesquiterpene lactones: VII. Palladium-catalyzed cross-coupling of isoalantolactone with 5-halouracils

Palladium-catalyzed cross-coupling of isoalantolactone with 1,3-disubstituted or 1-substituted 5-bromo(iodo)uracils afforded mainly (13E)-13-(2,4-dioxotetrahydropyrimidin-5-yl)eudesma-4(15),11(13)-dien-8β,12-olides whose yields depended on the composition of the catalytic system, base, and additive. The structure of (13E)-13-[3-(2-cyanoethyl)-2,4-dioxotetrahydropyrimidin-5-yl]eudesma-4(15),11(13)-dien-8β,12-olide was proved by X-ray analysis.     

Synthesis of annelated derivatives of tetrafluoro-10<Emphasis Type="Italic">H</Emphasis>-imidazo[1,2-<Emphasis Type="Italic">b</Emphasis>][1,2]benzooxazin-10-one and 2-pentafluorophenylpyrazine 1,4-dioxide by condensation of alicyclic 2-hydroxyamino oximes with pentafluorophenylglyoxal

Reactions of alicyclic 2-hydroxyamino oximes with pentafluorophenylglyoxal afford mixtures of annelated derivatives of 2-pentafluorophenylpyrazine 1,4-dioxide and tetrafluoro- 10H-imidazo[1,2-b][1,2]benzooxazin-10-one. The structures of the latter were established by X-ray diffraction analysis.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1636–1639, August, 2004.     

Transformations of conjugated enamines of the imidazolidine 1-oxide series in the Vilsmeier-Haack reaction

In some cases, the reactions of enaminones of the imidazolidine 1-oxide series with the Vilsmeier reagent afford electrophilic substitution products containing the dimethyl-aminomethylene group. In an acidic medium, these products undergo either hydrolytic elimination of the dimethylaminomethylene moiety or hydrolysis of the latter to form the aldehyde group. The reaction of nitroenamine, which is a derivative of imidazolidine 1-oxide, with the Vilsmeier reagent produces furoxane, viz., the nitroxyl biradical. Reduction of the latter affords the dioxime biradical. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1165–1170, June, 2007.     

Synthesis, structure, and X-band (9.5 GHz) EPR characterization of the new series of pH-sensitive spin probes: N,N-disubstituted 4-amino-2,2,5,5-tetramethyl-3-imidazoline 1-oxyls

[reaction: see text] An approach to the synthesis of new imidazoline nitroxides bearing an N',N'-disubstituted amidine group is reported. The approach is based on the alkylation of diamagnetic 4-R-amino-1,2,2,5,5-pentamethyl-3-imidazolines with bromoacetic acid ethyl ester; the products of alkylation are further oxidized to the corresponding nitroxides. The approach allows a variety of functional groups to be introduced into the nitroxide molecule structure. Alkylation with bromoacetic acid ethyl ester was found to proceed with high regioselectivity and afford the products of exo-alkylation. The regiochemical assignment is made on the basis of 13C NMR spectra and confirmed by X-ray diffraction study. All of the nitroxides synthesized here were shown to have pH-dependent EPR spectra with pKa ranging from 3.5 to 6.2. For nitroxides 13 bearing the carboxylic group remote to the nitroxide moiety, the changes in isotropic magnetic parameters of EPR spectra due to reversible deprotonation of the carboxylic group were found to be small. For these nitroxides, we demonstrate an alternative approach for pKa determination that is based on measuring the peak-to-peak line width of the EPR spectrum in the presence of the paramagnetic broadening agent potassium ferricyanide. The partition coefficients of nitroxides in octanol/H2O and octanol/phosphate buffer solution mixtures were measured to reveal a range of their lipophilicities.