Margarita A. Epishina

Synthesis of hetarylsulfanyl- and hetaryloxyfuroxans by nucleophilic substitution of nitro group in nitrofuroxans with heterocyclic thiol and hydroxy derivatives*

We report a general method for the synthesis of previously unknown heterocyclic systems containing furoxan and heterocyclic fragments linked by S- and О-bridges, based on nucleophilic substitution of nitro group in 4-nitrofuroxans with HetS and HetO groups introduced by reactions with hetarylthiols and hydroxy heterocycles in 1,8-diazabicyclo[5.4.0]undec-7-ene/МеCN system at room temperature. We showed that hetarylthiols reacted with 4-nitrofuroxans containing aliphatic, benzyl, and aromatic substituents at the ring С-3 atom, allowing to obtain a library of previously unknown hetarylsulfanylfuroxans, while the reaction with hydroxy heterocycles was successful only in the case of 4-nitro-3-phenylfuroxan, the rest of the nitrofuroxans showing low reactivity, and substitution products could be obtained only in certain cases. 4-Nitrofuroxans with electron-withdrawing substituents (NO2, CONH2) acted as oxidants, forming 1,2-di(hetaryl)disulfides.

Design of hybrid heterocyclic systems with a furoxanylpyridine core via tandem hetero-Diels–Alder/retro-Diels–Alder reactions of (1,2,4-triazin-3-yl)furoxans

Two convenient, facile, regioselective and highly effective one-pot protocols for the synthesis of previously unknown hybrid heterocyclic systems with the furoxanylpyridine core based on the tandem inverse-electron-demand hetero-Diels–Alder/retro-Diels–Alder reactions of the tailor-made (1,2,4-triazin-3-yl)furoxans with 1-(pyrrolidino)cyclohexene and norbornadiene have been developed. The methods comprise [4 + 2] cycloaddition of enamine or norbornadiene to the 1,2,4-triazine ring of (1,2,4-triazin-3-yl)furoxans followed by one-pot transformation of the formed intermediates and this affords an extensive series of polyheterocyclic ensembles combining furoxan and pyridine (tetrahydroisoquinoline, indenopyridine, terpyridine) rings in one molecule through a C–C bond in good to excellent yields.

An effective synthesis of (1Н-1,2,4-triazol-3-yl)furoxans

A general, simple, and effective method has been developed for the preparation of previously practically unknown (5-R-1Н-1,2,4-triazol-3-yl)furoxans with various substituents at the other carbon atom of furoxan ring, based on condensation of furoxanylamidrazones with electrophilic reagents (cyanogen bromide, acetic and trifluoroacetic anhydrides).

Synthesis and Transformations of Nitrogen Heterocycles in Ionic Liquids (Review)

A review is given for our work in the Nitrogen Compound Laboratory of the Institute of Organic Chemistry of the Russian Academy of Sciences over the past 10 years on the use of ionic liquids as reaction media and catalysts in the 1,3-dipolar cycloaddition of various 1,3-dipoles, such as azomethine imines, azides, and nitrile oxides, including domino reactions for the expansion of the three-membered diaziridine ring in monocyclic diaziridine derivatives and condensation reactions such as the synthesis of aminothiadiazoles and dihydroisoquinolines. The Schmidt rearrangement and Henry and Mannich reactions of polynitroalkanes in ionic liquids are also discussed.

Synthesis and nitration of 3-R-4-(2,2,2-trinitroethyl)aminofuroxans

Simple methods for the synthesis of 3-R-4-(2,2,2-trinitroethyl)aminofuroxans were developed based on the Mannich reaction of N,N′-bis(3-R-furoxan-4-yl)methylenediamines with trinitromethane or 3-R-4-aminofuroxans with trinitroethanol or with CH2O and trinitromethane. The Mannich bases obtained were studied in the nitration reaction, which showed their ability to form nitramines depending on substituents on the furoxan ring.

Synthesis of 3-amino-5-nitrobenzaldehyde oxime and its conversion into 3,4-bis(3-amino-5-nitrophenyl)furoxan and isomeric 3(4)-(3-amino-5-nitrophenyl)-4(3)-nitrofuroxans

The oxime of the hitherto unknown 3-amino-5-nitrobenzaldehyde was synthesized by the reaction of 3-amino-5-nitrobenzaldehyde phenylhydrazone with excess of (NH2OH)2·H2SO4. The oxime obtained was used as the starting compound for the synthesis of novel diaryl- and arylnitrofuroxans.

Synthesis and antineoplastic properties of (1H-1,2,3-triazol-1-yl)furazans

A method of 3-amino-4-[5-aryl(heteroaryl)-1H-1,2,3-triazol-1-yl)]furazan synthesis was optimized. Condensation of these compounds with 2,5-dimethoxytetrahydrofuran resulted in a series of previously unknown 4-[5-aryl(heteroaryl)-1H-1,2,3-triazol-1-yl)]-3-(pyrrol-1-yl)furazans. All target compounds were evaluated for both antimitotic microtubule destabilizing effect in a phenotypic sea urchin embryo assay and cytotoxicity in a panel of 60 human cancer cell lines. Pyrrolyl derivatives of triazolylfurazans were determined as antiproliferative compounds. The most potent microtubule targeting compounds 7a and 7e are of interest for further trials as antineoplastic agents.

Effective synthesis of 7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines

A highly effective method for the preparation of 7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines was developed on the basis of condensation reaction between aryl(hetaryl) α-bromo ketones and commercially available thiocarbohydrazide, followed by treatment of the obtained 2-hydrazinyl-6H-1,3,4-thiadiazine hydrobromides with ortho esters in the presence of trifluoroacetic acid under mild conditions.

Synthesis of bis(pyrimidyl)furoxanes by the oxidation of bis(pyrimidyl)glyoximes

ConclusionsThis is the first report of the synthesis of a 3,4-bis(pyrimidyl)furoxane by the oxidation of bis (pyrimidyl)glyoxime. The substrate used was 1,2-bis(2,4-diethoxypyrimidin-6-yl) glyoxime.