Nucleophilic substitution in benzo-1,2,3,4-tetrazine 1,3-dioxides

Nucleophilic substitution in nitro- and bromobenzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) was studied. In most cases, the bromo and nitro groups are replaced by methylamino, dimethylamino, azido, and methoxy groups without opening of the tetrazine ring. It was illustrated with the reactions of dibromo-BTDOs with sodium methoxide that the reactivity of positions 5 to 8 in their benzene ring as regards nucleophilic substitution changes in the following order: 6 > 8 > 7 > 5. The structures of the BTDOs obtained were confirmed by ¹H, ¹³C, and ¹⁴N NMR data.     

Synthesis of 1,2,3,4-tetrazino[5,6-g]benzo-1,2,3,4-tetrazine 1,3,7,9-tetraoxides

1,2,3,4-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. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1595–1599, September, 2006.     

Annulated benzotetrazine 1,3-dioxides 2.* [1,2,5]Oxadiazolo[3,4-f ][1,2,3,4]benzotetrazine 1,3,7-trioxide

Thermolysis of 8-azido-7-nitrobenzotetrazine 1,3-dioxide led to benzotetrazine 1,3-dioxide annulated with the furoxan ring at the C(7)—C(8) bond. Complete assignment of the signals in the ¹³C NMR spectrum of the compound obtained was performed. Attempted syntheses of benzotetrazine 1,3-dioxides annulated with a furoxan ring at the C(6)—C(7) bond or two furoxan rings at the C(5)—C(6) and C(7)—C(8) bonds were unsuccessful. Published in russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 341–345, February, 2006.     

Synthesis and structures of pyridoannelated 1,2,3,4-tetrazine 1,3-dioxides

Treatment of 2- and 4-amino-3-(tert-butyl-NNO-azoxy)pyridines with nitrating agents (N₂O₅or NO₂BF₄) afforded the first representatives of pyridoannelated 1,2,3,4-tetrazine di-N-oxides, viz., pyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (9), 7-nitropyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (10), and pyrido[3,4-e][1,2,3,4]tetrazine 2,4-dioxide (11). These compounds were studied by ¹H, ¹³C, and ¹⁴N NMR spectroscopy. The 1:1 complex of compound 10 with benzene was studied by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2471–2477, November, 2004.     

Annulated benzotetrazine 1,3-dioxides 1. [1,2,5]Oxadiazolo[3,4-f][1,2,3,4]benzotetrazine 2,4,7-and 2,4,9-trioxides

Thermolysis of 6-azido-5-nitro-7-R-benzotetrazine 1,3-dioxides (R = H and Br) gave benzotetrazine 1,3-dioxides annulated with the furoxan ring at the C(5)-C(6) bond. According to the NMR data, these compounds at 297 K are equilibrium mixtures of two isomers with different positions of the N-oxide oxygen atom in the furoxan ring. Full assignment of signals in the ¹³C NMR spectra of the compounds obtained was accomplished. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 133–136, January, 2006.     

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. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 3, pp. 480–484, March, 2000.     

Nitration and bromination of benzo-1,2,3,4-tetrazine 1,3-dioxides

Benzo-1,2,3,4-tetrazine 1,3-dioxide (BTDO) and its derivatives were nitrated with HNO₃/H₂SO₄ or HNO₃/oleum and brominated with dibromoisocyanuric acid in CF₃CO₂H/H₂SO₄ (5 : 1) or H₂SO₄. The reactivity of positions in the benzene ring of this heterocyclic system as regards electrophilic substitution was found to change in the following order: 5 7 > 8 > 6. Mono- and dinitro-BTDOs and mono- and polybromo-BTDOs were synthesized. Their structures were confirmed by ¹H, ¹³C, and ¹⁴N NMR spectra.     

Photochemical isomerization of 2H-imidazoleN-oxides

1,3-Diaza-6-oxabicyclo[3.1.0]hex-3-enes and their 3-oxides were obtained by the photolysis of 2H-imidazole 1-oxides and 2H-imidazole 1,3-dioxides. 1,3-Diaza-6-oxabicyclo [3.1.0]hex-3-ene 3-oxides are thermally unstable and are converted to the starting 2H-imidazole 1,3-dioxides; their further photolysis affords a mixture of stereoisomeric 1,3-diaza-4,7-dioxatricyclo [4.1.0.0^3,5]heptanes.For the previous communication, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2096–2100, December, 1993.     

Synthesis and Investigation of 1,2,3,4-Thiatriazol-5-ylcarbamates

Methyl 1,2,3,4-thiatriazol-5-ylcarbamate (2a), ethyl 1,2,3,4-thiatriazol-5-ylcarbamate (2b), 2-butyl 1,2,3,4-thiatriazol-5-ylcarbamate (2c), allyl 1,2,3,4-thiatriazol-5-ylcarbamate (2d), and 3-(1,2,3,4-thiatriazol-5-yl)oxazolidin-2-one (2e) were synthesized with high yields by the reaction of the corresponding carbon(isothiocyanatidic) acid, alkyl esters, and sodium azide in aqueous solution. The compounds were characterized by ¹H, ¹³C, and ¹⁵N NMR, vibrational spectroscopy (IR), and single crystal X-ray diffraction. The thermal stability was investigated by differential scanning calorimetry.     

First example of the formation of bipolar spiro σ-complexes from 6-bromo-5,7-dinitrobenzo[e]-1,2,3,4-tetrazine 1,3-di-N-oxide

The reactions of 3,5,7-trimethyltropolone and 2-(N-benzylamino)tropone with 6-bromo-5,7-dinitrobenzo[e]-1,2,3,4-tetrazine 1,3-di-N-oxide afforded novel bipolar spiro -complexes. The kinetic and activation parameters of the R,S-enantiotopomerization of a chiral spiro -complex of 2-(N-benzylamino)tropone were determined using dynamic ¹H NMR spectroscopy.     

Spectroscopic study of fused 1,2,3,4-tetrazine 1,3-dioxides

Vibrational spectra of furazano- and benzo-1,2,3,4-tetrazine 1,3-dioxides were studied, and the main regularities of the changes in frequencies of stretching vibrations of the tetrazine dioxide fragment with respect to the nature of the substituent in the benzene ring were established.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2187–2189, November, 1995.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-18461).     

Über die Oxo‐cyclotetraphosphane (PBut)4O1–4

Contributions to the Chemistry of Phosphorus. 243 On the Oxocyclotetraphosphanes (PBu^t)₄O_1–4 Under suitable conditions, the reaction of tetra‐tert‐butylcyclotetraphosphane, (PBu^t)₄, with dry atmospheric oxygen gives rise to the corresponding monoxide (PBu^t)₄O ( 1 ) which has been isolated by column chromatography. The reaction with hydrogen peroxide furnishes a mixture of oxocyclotetraphosphanes (PBu^t)₄O_1–4 consisting of two constitutionally isomeric dioxides (PBu^t)₄O₂ ( 2 a , 2 b ), the trioxide (PBu^t)₄O₃ ( 3 ), and the tetraoxide (PBu^t)₄O₄ ( 4 ), in addition to 1 . According to the ³¹P NMR parameters the oxygen atoms are exclusively exocyclically bonded to the phosphorus four‐membered ring. Which of the P atoms are present as λ⁵‐phosphorus follows from the different low‐field shifts of the individual P nuclei compared with the starting compound. Accordingly, 1 is 1,2,3,4‐Tetra‐tert‐butyl‐1‐oxocyclotetraphosphane, 2 a and 2 b are 1,2,3,4‐Tetra‐tert‐butyl‐1,2‐dioxo‐ and ‐1,3‐dioxocyclotetraphosphane, respectively, 3 is 1,2,3,4‐Tetra‐tert‐butyl‐1,2,3‐trioxocyclotetraphosphane, and 4 is 1,2,3,4‐Tetra‐tert‐butyl‐1,2,3,4‐tetraoxocyclotetraphosphane. When the oxidation reaction proceeds a fission of the P₄ ring takes place.     

Diels-alder reaction with cyclic sulfones. 9.* Synthesis of 10-oxo-1h-tetrahydrofluo-reno[2,1-b]thiophene dioxides*2

The treatment of 5-aryl-4′,6′-dioxo-2,3,3a,4,5,6-hexahydrospiro-[benzothiophene-4,5′-1,3-dioxane] 1,1-dioxides with boron trifluoride etherate in dichloroethane leads to the formation of products of intramolecular acylation, namely, the corresponding 10-oxo-1H-5,5a,10a,10b-tetrahydrofluoreno-[2,1-b]thiophene dioxides. In all cases, 5-aryl-4-carboxyhexahydrobenzo[b]thiophene 1,1-dioxides were also isolated. The product ratio depends on the structure of the aromatic substituent at C(5) of the spiro- adducts. The structure of 4-carboxy-5-(2-methoxyphenyl)-7-methyl -2,3,3a,4,5,6-hexahydro-benzo[b]thiophene 1,1-dioxide was confirmed by X-ray diffraction structural analysis. ^*For Communication 9 see [1]. ^*2Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1503–1512, October, 2008.     

Synthesis of 1,2,3,4-tetrazine 1,3-dioxides annulated with 1,2,3-triazoles and 1,2,3-triazole 1-oxides

1,2,3,4-Tetrazine 1,3-dioxides annulated with 1,2,3-triazoles and 1,2,3-triazole 1-oxides have been synthesized by the reaction of 4-amino-5-(tert-butyl-NNO-azoxy)-2-R-2H-1,2,3-triazoles (R=Me, i-Pr, t-Bu) and their 1-oxides (R=H, Me, Et, i-Pr) with the HNO₃/H₂SO₄/Ac₂O system. Their thermal stability, spectroscopic, and X-ray properties have been studied.     

An unusual cascade of <Emphasis Type="Italic">S</Emphasis><Subscript>N</Subscript> reactions of benzotetrazine 1,3-dioxide derivatives

An unusual cascade of S _NAr reactions was discovered in the series of benzo-1,2,3,4-tetrazine 1,3-dioxides containing two adjacent nucleofuges X and Y in the benzene ring. First, the 1,2,3-triazole anion displaces the anion X^s- from the more reactive site. Then the nucleo-phile X^s- displaces the adjacent group Y. For instance, 1,2,3-triazole reacts with 6-azido-5-nitrobenzotetrazine 1,3-dioxide to give 5-azido-6-(1,2,3-triazol-2-yl)benzotetrazine 1,3-dioxide, with 8-azido-7-nitrobenzotetrazine 1,3-dioxide to give 7-azido-8-(1,2,3-triazol-2-yl)benzotetrazine 1,3-dioxide and 7-azido-8-(1,2,3-triazol-1-yl)benzotetrazine 1,3-dioxide, and with 7-bromo-6-(phenylthio)benzotetrazine 1,3-dioxide to give 7-phenylthio-6-(1,2,3-triazol-2-yl)benzotetrazine 1,3-dioxide.     

Über die Reaktionen von monosubstituierten Guanidinen mit α,β-ungesättigten Ketonen

Action of methyl-, benzyl- and phenylguanidine on mesityloxide yields the 2-R ³-imino-4,4,6-trimethyl-1,2,3,4-tetrahydropyrimidines resp. 2-R³-aminopyrimidines8 b, c ande, cyclohexylidenacetone reacts with benzylguanidine to give the 2-benzylimino-4-methyl-1,3-diazaspiro[5.5]undeca-4-en resp. the benzylaminodiazaspiroundecadien (8 d). The isomeric 1- and 3-R³-pyrimidinimines (resp.-amines)9 b-e and10 b-e are not formed in the reaction. The structures were proved by spectroscopical and chemical methods.

Herrn Prof. Dr.G. Zigeuner zum 60. Geburtstag gewidmet.     

Use of 13C NMR Spectroscopy to Establish the Structure of 6(7)-R-Quinoxaline N,N′-Dioxides

The effect of substituents in position 6 on the positions of the signals of the carbon atoms in the ¹³C NMR spectra of substituted 1,2,3,4-tetrahydro-5,10-phenazine N,N′-dioxides has been analyzed, increments of substituents have been found, and a scheme has been proposed for the calculation of the chemical shifts of carbon atoms in the ¹³C NMR spectra of 6(7)-R-quinoxaline N,N′-dioxides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1076–1080, July, 2005.     

Calixcrowns and related molecules

The synthesis of 1,2- and 1,3-calix[4]-bis-crowns, double calix[4]arenes and double calixcrowns have been shown to depend on the reaction conditions (nature of the base, structure of the ditosylates, and the stoichiometry of the reactants). The 1,3-alternate conformation of the 1,3-calix[4]-bis-crowns was shown to be favourable to the selective complexation of cesium cation. The observed Na⁺/Cs⁺ selectivity was exploited in separation processes using them as carriers in transport through supported liquid membranes (SLMs). The best Na⁺/Cs⁺ selectivity (1/45 000) was observed for the naphthyl derivative 7. Calix(aza) crowns and 1,3-calix[4]-bis-(aza)-crowns were also produced through the preliminary formation of the Schiff base-calixarenes, which were further hydrogenated. The syntheses consisted of the 1,3-selective alkylation of calixarenes followed by cyclization into a 1,3-bridged calixarene or by the direct 1,3-capping of the calixarene with appropriate ditosylates. Soft metal complexation by these ligands is also presented.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

Ketendithioacetal-S-imide

Starting from 2-isopropylidene-1,3-dithiane, various ketene-dithioacetal-S-imides have been prepared and characterized by¹H- and¹³C-NMR spectra.

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Ketendithioacetal-S-imideKurze Mitteilung

     

On the regioselectivity of alkylation of the (trimethylsilyl)tetramethylcyclopentadienide anion. A new approach to the synthesis of 1,2,3,4-tetramethylfulvene

The regioselectivity of alkylation of lithium (trimethylsilyl)tetramethylcyclopentadienide C₅Me₄SiMe₃ ⁻Li⁺ was studied by ¹H and ¹³C NMR spectroscopy using its reactions with MeI, MeOTs, ClCH₂CH₂Br, and ClCH₂CH₂I in different solvents as representative examples. Sterically non-hindered MeI and MeOTs presumably attack the C atom bonded to the silyl group giving 1,2,3,4,5-pentamethylcyclopentadienylsilane. For bulkier alkyl halides, such as ClCH₂CH₂Br and ClCH₂CH₂I, the regioselectivity of alkylation changes to form preferentially gem-dialkyl-substituted cyclopentadienes. The reaction of C₅Me₄SiMe₃ ⁻Li⁺ with formaldehyde affords 1,2,3,4-tetramethylfulvene in a high yield, providing an alternative synthetic approach to a number of ω-functionalized peralkylated cyclopentadienes. The quantum-chemical calculations of the C₅Me₄SiMe₃ ⁻ anion by the RHF and DFT (RMPW1PW91) methods in the valence-split 6-311+G(d,p) basis set are in good agreement with the experimental data.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2089–2093, October, 2004.