Nadezhda V. Palysaeva

Ionic Liquids as Unique Solvents in One‐Pot Synthesis of 4‐(N,2,2,2‐Tetranitroethylamino)‐3‐R‐Furazans

An efficient two-step one-pot protocol for the synthesis of N-nitrated trinitroethylamino furazans in an ionic liquid has been developed involving the condensation of aminofurazans with trinitroethanol and the N-nitration of an intermediate Mannich base. Trinitroethylnitramino derivatives have been synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallography. A role of the N,2,2,2-tetranitroethylamino group for stabilization of the high-density crystal-packing motif is described. The performance calculations gave detonation pressures and velocities for the furazan derivatives in a range of about 31-36 GPa and 8330-8745 ms(-1), respectively, which makes them competitive energetic materials. Furthermore, due to the positive oxygen balance, the compounds could be potential oxidizers for energetic formulations.

A Direct Approach to a 6-Hetarylamino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine Library

The synthesis of 6-hetarylamino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines is reported. The functionalized secondary amines were constructed via a K2CO3-mediated SNAr reaction of weakly basic hetarylamines with 3-(3,5-dimethylpyrazol-1-yl)[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines, which allowed displacement 3,5-dimethylpyrazolyl leaving group. Significantly, the reaction exhibited a broad substrate scope and proceeded in good yields.

A practical anodic oxidation of aminofurazans to azofurazans: an environmentally friendly route

Nickel oxyhydroxide, NiOOH, anode has been shown to be an effective tool for the oxidation of aminofurazans to azofurazans in ca. 1% aqueous alkali at room temperature. The electrochemical reaction is simple and convenient, eliminating the use of expensive and toxic organic or inorganic oxidants. The green economic preparation of desired azo compounds is very clean, producing only H2 as a result of cathodic reduction.

Novel trinitroethanol derivatives: high energetic 2-(2,2,2-trinitroethoxy)-1,3,5-triazines

The multicomponent reaction of 2,4,6-trichloro-1,3,5-triazine with potassium trinitromethane and trinitroethanol was exploited for the first synthesis of the hetaryl trinitroethyl ether, 2,4-bis(2,2,2-trinitroethoxy)-6-trinitrometyl-1,3,5-triazine 13. The use of compound 13 as a scaffold for the synthesis of substituted trinitroethoxytriazine by sequential nucleophilic substitution processes is described. A number of trinitroethoxytriazines bearing a range of functional groups, including 2,4,6-tris(2,2,2-trinitroethoxy)-1,3,5-triazine 16, have been prepared. There has been no previous incorporation of the trinitroethoxy moiety to a heteroaromatic ring. All trinitroethoxytriazines were fully characterized using IR and multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC), and, in some cases, 16, 20 and 21, with single crystal X-ray structuring. When compared to the aliphatic trinitroethoxy compounds, the trinitroethoxytriazines show better energetic performance as calculated. The impact sensitivities and ignition points of the novel oxygen and nitrogen-rich triazines were measured. The ability of the applied trinitroethoxytriazines in solid composite propellants as well as in gas generant compositions for airbag inflators was evaluated. The straightforward preparation of these ethers highlights them as valuable new environmentally friendly and high-performing nitrogen and oxygen-rich materials.

A facile synthesis and microtubule-destabilizing properties of 4-(1H-benzo[d]imidazol-2-yl)-furazan-3-amines

A series of 4-(1H-benzo[d]imidazol-2-yl)-furazan-3-amines (BIFAs) were prepared in good yields (60-90% for each reaction step) via a novel procedure from aminofurazanyl hydroximoyl chlorides and o-diaminobenzenes. The synthetic sequence was run under mild reaction conditions, it was robust and did not require extensive purification of intermediates or final products. Furthermore, there was no need for protection of reactive moieties allowing for the parallel synthesis of diverse BIFA derivatives. Subsequent biological evaluation of the resulting compounds revealed their anti-proliferative effects in the sea urchin embryo model and in cultured human cancer cell lines. The most active compounds showed 0.2-2 μM activities in both assay systems. The unsubstituted benzene ring of the benzoimidazole template as well as the unsubstituted amino group in the furazan ring were essential prerequisites for the antimitotic activity of BIFAs. Compound 57 bearing the 2-chlorophenyl acetamide substituent at the nitrogen atom of the imidazole ring was the most active molecule in the examined set.

Synthesis of 4-Acyl-3-Aminofurazans from 3,4-Diacylfuroxans

It was shown that 3,4-diaroylfuroxans are transformed into the corresponding 3-amino-4-aroyl-furazans by heating in aqueous ammonia. The developed one-pot methodology for the synthesis of 3-amino-4-aroylfurazans involved the interaction of the corresponding acetophenones with nitric acid followed by treatment of the in situ formed furoxans with ammonia at elevated temperature. The structures of the obtained furazans were confirmed by IR, as well as by 1H and 13C NMR spectroscopy, and X-ray structural analysis was performed for 3-amino-4-(4-methoxybenzoyl)furazan.

6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetra-zin-3(2H)-one.

The title compound, C7H8N6O, represents the keto form and adopts a nearly planar structure (r.m.s. deviation of the non-H atoms = 0.072 Å). In the crystal, molecules form spiral chains along the c axis by N—H⋯N hydrogen bonds. The chains are linked to each other by weak C—H⋯O hydrogen bonds, forming a three-dimensional framework.

3-Methyl-4-(2-phenyl-1,2,4-triazolo[1,5-a]pyrimidin-7-yl)furazan.

In the title molecule, C14H10N6O, the planes of the methylfurazan fragment and the phenyl ring attached to the triazolopyrimidine bicycle are twisted from the mean plane of the bicycle at angles of 45.92 (5) and 5.45 (4)°, respectively. In the crystal, π–π interactions, indicated by short distances [in the range 3.456 (3)–3.591 (3) Å] between the centroids of the five- and six-membered rings of neighbouring molecules, link the molecules into stacks propagating along the c-axis direction.