V. M. Berestovitskaya

Synthesis of 4-Aryl-5-nitro-1,2,3-triazoles

It is known that some 1,2,3-triazole derivatives possess practically important properties. For example, 4-(4-methoxyphenyl)-5-nitro-1,2,3-triazole exhibits antifungal activity, and 4-(4-bromophenyl)and 4-(4nitrophenyl)-5-nitro-1,2,3-triazoles are tuberculostatic and fungicide agents [1]. Some 1,2,3-triazoles can be used as photostabilizers and optical bleaching agents [2, 3], and they may be regarded as precursors of azapurines which are potential carcinostatic agents [2]. The synthesis of nitro-1,2,3-triazoles having aryl substituents at the ring carbon atoms was described by Khisamutdinov and co-workers [1, 4]. It is based on the reaction of 2-aryl-1-bromo-1-nitroethenes or 2-aryl-1,2-dibromo-2-nitroethanes with sodium azide in aprotic (DMF, DMSO) or protic (ethanol) solvents. 1,1-Dinitroethene derivatives, specifically β,β-dinitrostyrenes, are highly reactive compounds [5–8] which can be used in the synthesis of nitro-1,2,3triazoles. We have shown that β,β-dinitrostyrenes I–III react with 2 equiv of sodium azide under fairly mild conditions, in anhydrous acetonitrile at room temperature. The reaction takes 2.5–4.5 h, and the products are 4-aryl-5-nitro-1,2,3-triazoles VII–IX which are formed in 59–77% yield. Compounds VII–IX were also synthesized by independent method from the corresponding β-bromo-β-nitrostyrenes and sodium azide in DMF, following a slightly modified procedure

Synthesis of pyrrole- and indole-containing nitropropanoates on the basis of β-heteryl-α-nitroacrylates

Synthetic approach to β-furyl- and β-thienyl-α-nitroacrylates was modified. It was established that these nitroethenes react with pyrrole, N-methylpyrrole, and substituted indole derivatives in the absence of catalyst to afford products of the alkylation of pyrrole C2 and indole C3 reaction sites. A possibility of this reaction to proceed under “dry reaction” condition on a silicagel surface was shown.

Synthesis and structure of β-aryl-α-nitroacrylates

The method for preparation of ethyl α-nitrocinnamates by nitroacetic acid ester alkenylation with aromatic aldehydes in the presence of acetic acid and β-alanine has been modified. Structures of the prepared compounds have been proved by electronic, IR, 1H, and 13C-{1H} NMR spectroscopy (including heteronuclear correlation experiments 1H-13C HMQC and 1H-13C HMBC). In solution these compounds exist in the form of Z-isomer; the Z⇄E isomerization is observed in the case of the compound containing strong electron-donor group [N(CH3)2] at benzene ring.

Aryl(hetaryl)-containing gem-cyanonitroethenes: Synthesis, structure, and reactions with 2,3-dimethyl-1,3-butadiene

Methods of aryl(hetaryl)-substituted gem-cyanonitroethenes preparation are summarized, and the products structure elucidation by means of 1H, 13C NMR, IR, and UV spectroscopy methods is discussed. E-Configuration of the compounds obtained has been proved. Reaction of the studied gem-cyanonitroethenes with 2,3-dimethyl-1,3-butadiene affords the diene synthesis adducts–6-aryl(hetaryl)-3,4-dimethyl-1-nitro-1-cyano- 3-cyclohexenes.

Geminal acylnitrostyrenes in the reaction with ortho-aminothiophenol

The synthesis of previously unknown 2,3- and 2,5-dihydro-1,5-benzothiazepines sontaining nitro group was performed by the easy sondensation of geminal acylnitrostyrenes with the o-aminothiophenol. The structure of the obtained sompounds was studied by physicochemical methods. By X-ray diffraction analysis the geometry and structural parameters of 4-methyl-3-nitro-2-phenyl-2,3-dihydro-1,5-benzothiazepine were determined.

β-Acetyl-β-nitrostyrenes: Structure and use for synthesis of heteryl-containing structures

Abstract1H, IR, and electronic absorption spectroscopy and X-ray diffraction analysis were used to establish that 1-acetyl-1-nitro-2-phenyl-and 2-(p-methoxyphenyl)ethenes have Z configuration, and their 2-(p-N,Ndimethylaminophenyl)-substituted analog exists in chloroform-d3 as a mixture of Z and E isomers. The reactions of gem-acetylnitroethenes with N-methylpyrrole were shown to involve alkylation at the C2-reaction center of the heterocycle. The reactions of these nitroalkenes with hydrazine form pyrazoles and azines, with acetylhydrazine, the corresponding hydrazones (via transalkenylation), and with sodium azide, acetylsubstituted 1,2,3-triazoles.

Reactions of 2-benzylidene-3-methyl-4-nitro-2,5-dihydrothiophene 1,1-dioxide with CH acids

Abstract2-Benzylidene-3-methyl-4-nitro-2,5-dihydrothiophene 1,1-dioxide reacted with acyclic CH acids (acetylacetone, diethyl malonate, and its derivatives) according to the 1,4-addition pattern, whereas reactions of the title compound with cyclohexane-1,3-dione and 5,5-dimethylcyclohexane-1,3-dione (dimedone) were complicated by subsequent intramolecular heterocyclization leading to thieno[3,2-b]chromene derivatives.

Conformational Analysis of 2-Substituted 1-Nitro- and 1-Bromo-1-nitroethenes

Conformational analysis of 2-trichloromethyl(ethoxycarbonyl)-1-nitro-and 2-trichloromethyl-(ethoxycarbonyl)-1-bromo-1-nitroethenes was performed using the dipole moment method, IR spectroscopy, and DFT quantum-chemical calculations (B3LYP/6-31G*). The nitro and ester (or trichloromethyl) groups in the molecules of these compounds were found to occupy trans positions with respect to the double C=C bond, i.e., the nitroalkenes have E, and their bromine-containing analogs, Z configuration; the compounds having an ethoxycarbonyl group are characterized by s-cis orientation of the C=C and C=O bonds.

3-(Nitromethyl)-3,4-dihydroquinoxalin-2(1H)-ones: synthesis and structure

Reactions of ethyl 3-nitroacrylate with o-phenylenediamine and its substituted derivatives were used for the synthesis of 3-(nitromethyl)-3,4-dihydroquinoxalin-2(1H)-ones, followed by structural characterization. These compounds were found to undergo elimination of nitromethane, leading to quinoxalin-2(1H)-ones.

Polarity and structure of 2-(1-methylbenzimidazol-2-yl)-1-phenyl- and -1,2-diphenyl-1-nitroethenes

Polarity of 2-(1-methylbenzimidazol-2-yl)-1-phenyl- and -1,2-diphenyl-1-nitroethenes was determined and their structure was studied using electronic and 1H, 13C NMR spectroscopy, dipole moments measuring, XRD analysis, and quantum-chemical calculations. It was shown that the 2-(1-methylbenzimidazol-2-yl)-1-nitro-1-phenylethene has Z-configuration both in crystal and solution. The nitro group and benzimidazole substituent in its molecule are removed from the plane of the double bond. For 1,2-diphenyl-1-nitroethene E-structure is typical.