A. M. Churakov

Synthesis of Tetrazino‐tetrazine 1,3,6,8‐Tetraoxide (TTTO)

This study presents the first synthesis and characterization of a new high energy compound [1,2,3,4]tetrazino[5,6-e][1,2,3,4]tetrazine 1,3,6,8-tetraoxide (TTTO). It was synthesized in ten steps from 2,2-bis(tert-butyl-NNO-azoxy)acetonitrile. The synthetic strategy was based on the sequential closure of two 1,2,3,4-tetrazine 1,3-dioxide rings by the generation of oxodiazonium ions and their intramolecular coupling with tert-butyl-NNO-azoxy groups. The TTTO structure was confirmed by single-crystal X-ray.

Benzo-1,2,3,4-tetrazine 1,3-Dioxides: Synthesis and NMR Study

Benzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) represent fairly stable high-nitrogen systems, incorporating two head-to-tail linked azoxy groups. The synthetic pathway to these heterocycles suggested the use of the tert-butyl-NNO-azoxy group as a building block, allowing the first azoxy group to be incorporated into the ring. The second azoxy group was added with the help of the oxodiazonium ion (−N=N=O+) or its synthetic equivalent. This could be generated by two new methods. The first of these involved treatment of N-nitroamines with nitrating agents, and the second treatment of diazonium salts with peracids in the presence of a base. The proposed key stage in the tetrazine 1,3-bis(N-oxide) ring formation is the reaction between the oxodiazonium ion and the distal nitrogen atom of the tert-butyl-NNO-azoxy group, followed by elimination of the tert-butyl cation. The syntheses of bromo-BTDOs 3b−f and nitro-BTDOs 4a−c are described. The BTDOs were characterized by NMR, including 14N and 15N experiments. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Synthesis of 1,2,3,4-tetrazino[5,6-f]benzo-1,2,3,4-tetrazine 1,3,7,9-tetra-N-oxides.

Abstract1,2,3,4-Tetrazino[5,6-g]benzo-1,2,3,4-tetrazine 1,3,7,9-tetraoxides, which possess an-thracene-type annulation of the benzene ring with two 1,2,3,4-tetrazine 1,3-dioxide fragments, were obtained for the first time from aminobenzenes containing tert-butyl-NNO-azoxy groups in appropriate positions. Complete assignments of the signals in the 1H, 13C, and 14N NMR spectra of the compounds obtained were carried out.

New approach to the synthesis of benzo[e][1,2,3,4]tetrazine 1,3-dioxides

A new approach to the synthesis of benzo[e][1,2,3,4]tetrazine 1,3-dioxides involves the treatment ofN-nitroanilines containing anortho-(tert-butyl-NNO-azoxy) group with phosphoric anhydride or phosphorus pentachloride. The reaction is supposed to proceed through an intermediate diazonium oxide cation.

Nucleophilic Aromatic Substitution of Hydrogen in the Reaction oftert-Alkylamines with Nitrosobenzenes – Synthesis and NMR Study ofN-(tert-Alkyl)-ortho-nitrosoanilines

The reaction of primary amines bearing tertiary alkyl groups (e.g. R–NH2; R = tBu, 1-adamantyl) with nitrosobenzenes has been found to proceed by oxidative nucleophilic aromatic substitution of hydrogen, thereby affording N-(tert-alkyl)-ortho- and -para-nitrosoanilines. The replacement of hydrogen proceeds more rapidly than the replacement of ortho- or para-nitro or -bromo substituents. With p-nitronitrosobenzene, both ortho-hydrogen atoms are substituted to afford N,N′-di(tert-alkyl)-4-nitro-2-nitroso-1,3-phenylenediamines 8a,b. The addition of oxidizing agents (e.g. MnO2) increases the yield of products. 1H-, 13C-, 14N- and 15N-NMR studies have confirmed the structures of the compounds under investigation. In ortho-nitrosoanilines, the rotamer with the nitroso group syn to the amino group is favored.

New approaches to synthesis of tris[1,2,4]triazolo[1,3,5]triazines

Thermal cyclization of 3-R-5-chloro-1,2,4-triazoles (R = Cl, Ph) afforded 2,6,10-tri-R- tris[1,2,4]triazolo[1,5-a:1′,5′c:1″,5″-e][1,3,5]triazines 5 (R = Ph) and 7 (R = Cl). These compounds are first representatives of this class of heterocycles, whose structures were unambiguously established. Treatment of these compounds with nucleophiles (H2O/NaOH, NH3) results in the triazine ring opening to give compounds consisting of three 1,2,4-triazole rings linked in a chain. For example, treatment of cyclic compound 5 with aqueous alkali affords 3-phenyl-1-3-phenyl-1-(3-phenyl-1H-1,2,4-triazol-5-yl)-1,2,4-triazol-5-yl-1H-1,2,4-triazol-5-one. Treatment of 3,7,11-triphenyltris[1,2,4]triazolo[4,3-a:4′,3′c:4″,3″-e][1,3,5]triazine (2) with HCl/SbCl5 leads to the triazine ring opening giving rise to 5-(3-chloro-5-phenyl-1,2,4-triazol-4-yl)-3-phenyl-4-(5-phenyl-1H-1,2,4-triazol-3-yl)-1,2,4-triazole. Thermal cyclization of the latter produces 3,7,10-triphenyltris[1,2,4]triazolo[1,5-a:4′,3′c:4″,3″-e][1,3,5]triazine (13). Thermolysis of both cyclic compound 2 and cyclic compound 13 is accompanied by the Dimroth rearrangement to yield 3,6,10-triphenyl-tris[1,2,4]triazolo[1,5-a:1′, 5′-c:4″,3″-e][1,3,5]triazine (14). Compounds 13 and 14 are the first representatives of cyclic compounds with this skeleton. 13C NMR spectroscopy allows the determination of the isomer type in a series of tris[1,2,4]triazolo[1,3,5]triazines.

Synthesis of 1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 4,6-dioxide and its methyl derivatives

Abstract1H-[1,2,3]Triazolo[4,5-e][1,2,3,4]tetrazine 4,6-dioxide (3) was synthesized by reduction of 1-hydroxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide (1) with PCl3, reduction of 1-methoxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide (4) with Na2S2O4, and by the reaction of compound 4 with Et3N. Both methylation of compound 3 with diazomethane and reaction of Ag-salt of compound 3 with MeI occur at the triazole cycle to give all three possible isomers. The structures of the synthesized compounds were confirmed by 1H, 13C, 14N, and 15N NMR spectroscopy.

Amino(tert-butyl-NNO-azoxy)furoxans: synthesis, isomerization, and rearrangement of N-acetyl derivatives

Abstract3-Amino-4-(tert-butyl-NNO-azoxy)furoxan (1a) and 4-amino-3-(tert-butyl-NNO-azoxy)-furoxan (1b) and their acetyl derivatives 6a,b were obtained. The equilibria 1a ai 1b and 6a ⇒ 6b were studied. Furoxan 6b can undergo thermal rearrangement into 3-[(tert-butyl-NNO-azoxy)(nitro)methyl]-5-methyl-1,2,4-oxadiazole (7), prolonged heating of which gives N-(2-tert-butyl-5-nitro-1-oxido-2H-1,2,3-triazol-4-yl)acetamide (8). With the transformation 7 → 8 as an example, the possibility of participation of the azoxy group in the Boulton-Katritzky rearrangements was demonstrated for the first time.

Synthesis of 4H-[1,2,3]triazolo[4,5-c][1,2,5]oxadiazole 5-oxide and its N- and O-alkyl derivatives

Abstract The synthetic route to the fused 1,2,3-triazole 2-oxide systems via intramolecular cyclization of N-nitroso and azido groups is described. The title compounds are characterized by 1H, 13C, 14N, 15N and 17O NMR spectroscopy.

A synthesis of 1-hydroxybenzo-1,2,3-triazole 3-oxide

Abstract The intramolecular reaction of the nitroso group with the azoxy side-chain in 2-( tert -butyl)-1-(2-nitrosophenyl)diazene 1- N -oxide provides the key step in a synthesis of the previously unknown 1-hydroxybenzo-1,2,3-triazole 3-oxide.