α-Bromoacetyl derivatives of furazan and furoxan

Bromination of acetylfurazans and furoxans has been studied. The conditions for the synthesis of bromoacetyl derivatives have been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 744–746, April, 1993.     

Reactions of bromoacetyl derivatives of furoxan and furazan with S-nucleophiles

Hetarylthioacetyl- and (2-aminothiazol-4-yl)furoxans and the corresponding furazans unknown previously were synthesized by the reactions of substituted bromoacetylfuroxans and-furazans with hetarylthiols and thiourea, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 137–141, January, 1998.     

Nitrophenyl derivatives of the furazan and furoxan ring systems

The preparation of some nitrophenyl derivatives of the furazan and furoxan ring systems is reported. The results of an antimicrobial screening on these compounds are also briefly discussed.     

Synthesis of 1-hydroxybenzotriazoles angularly annulated by furazan or furoxan rings

Synthesis of 6-hydroxy-6H-[1,2,3]triazolo[4,5-e][2,1,3]benzoxadiazole and a mixture of isomeric 6-hydroxy-6H-[1,2,3]triazolo[4,5-e][2,1,3]benzoxadiazole-1(3)-oxides is carried out starting from 2,4-dinitrosoresorcinol. Total assignment of the signals in the ¹³C NMR spectra of O-methylated products of these compounds is performed.     

Energetic materials based on poly furazan and furoxan structures

Furazan and furoxan represent fascinating explosophoric units with intriguing structures and unique properties. Compared with other nitrogen-rich heterocycles, most poly furazan and furoxan-based heterocycles demonstrate superior energetic performances due to the higher enthalpy of formation and density levels. A large variety of advanced energetic materials have been achieved based on the combination of furazan and furoxan moieties with different kinds of linkers and this review provides an overview of the development of energetic poly furazan and furoxan structures during the past decades, with their physical properties and detonation characteristics summarized and compared with traditional energetic materials. Various synthetic strategies towards these compact energetic structures are highlighted by covering the most important cyclization methods for construction of the hetercyclic scaffolds and the following modifications such as nitrations and oxidations. Given the synthetic availabilities and outstanding properties, energetic materials based on poly furazan and furoxan structures are undoubtedly listed as a promising candidate for the development of new-generation explosives, propellants and pyrotechnics.     

Spectral-luminescent properties of oxazole derivatives with annelated aromatic and heterocyclic rings in neutral and acid media

An investigation was carried out of the spectral-luminescent and acid-base properties at the stage of formation of the hydrogen bond and during the protonation of compounds with annelated aromatic and heterocyclic rings, obtained by introduction of bridging groups -CH=CH- (I), -CH=N- (II) and -CO-N(CH₃)-(III) in the 4- and 2-positions of the molecules of 4-substituted derivatives of 2,5-diphenyloxazole. The nature of the reaction center was estabished, and an analysis was carried out of its sensitivity to the electronic influence of the substituents, and the reasons for the observed differences in the properties of compounds of various reaction series are discussed. A comparative analysis of the fluorescent properties of the neutral and protonated forms of the oxazole derivatives studied was made and the conclusion that the generation is possible of laser emission by the protonated forms of compounds of the reaction series (I) was confirmed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 343–349, July–August, 1992.     

The directing effect of annelated rings in aromatic systems—XI : Bromination of bicyclic phenols with heterocyclic annelated rings

Bicyclic phenols of type 1 with annelated rings containing a N or an O heteroatom (X = N or O) as well as the ring opened analogs have been brominated and the product distribution determined. The results indicate that while most annelated rings have a directing effect to the ar-β position of the molecule, a 6-membered annelated ring is an exception and it facilitates substitution in the ar-α position.     

Vibration spectra and quantum chemical calculation of optoelectronic and force parameters of furazan and furoxan

Vibration spectra of furoxan in liquid and crystalline states are investigated. Force constants and optoelectronic parameters of furazan and furoxan are calculated by MINDO/3. Their values are compared with those obtained by solving inverse spectral problems. It is shown that the band at 1605 cm⁻¹, which is characteristic of all furoxans, is due to vibrations of the C=N(−>0) group. Kazan Technological University. Kazan Construction Engineering Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 6, pp. 54–59, November–December, 1994 Translated by L. Smolina     

Reduction of the furoxan ring to the furazan ring in some carbonyl-substituted furoxans

It was shown that the furoxan ring is efficiently reduced to the furazan ring in carbonylsubstituted furoxans with other functional groups by the action of the SnCl₂-HC1-AcOH system.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 679–680, April, 1994.     

Synthesis and cytotoxic activity of new annulated furazan derivatives

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Syntheses,structure, and electrochemical properties of unsymmetrical crown‐annelated TTF derivatives

A series of new crown‐ether annelated TTF derivatives 2a, 2b, 2c, 3 and 5 have been synthesized and characterized by melting points, NMR, IR and ESI‐MS. The crystal structure of compound 3 , 2, 3‐dithia‐(5′,8′‐dioxaoctyl)‐6,7‐ethylenedithiatetrathiafulvalene, has been determined by X‐ray crystallography. Redox properties of all these compounds have been investigated by cyclic voltammetry and each compound shows two reversible single‐electron redox couples. The results indicate that 3 is responsive for Li⁺, but not to other alkali metal cations, such as Na⁺ and K⁺. Although with the same cavity, compounds 2c and 5 show marked changes upon the addition of sodium perchlorate, while there is no significant response for 2a and 2b at the same condition.     

Study of synthesis and cardiovascular activity of some furoxan derivatives as potential NO-donors

A series of hybrid molecules incorporating the furoxan and nicorandil moieties were designed as potential NO donors with cardiovascular and cerebrovascular activities. Thirty-six target molecules were successfully synthesized by conventional methods and characterized by infrared spectroscopy, 1H-NMR spectroscopy and high resolution mass spectra. The compounds were tested for their effects on KCl-induced contraction of rabbit thoracic aorta whose endothelium was denuded. Eight compounds were found to reduce KCl-induced contraction by more than 30% at 10 microM. All except one of these compounds are characterized by the presence of electron withdrawing groups in the phenyl ring attached via an amide or ester linkage to the furoxan moiety. The nature of the terminal carbonyl linkage (ester or amide) and the length or type of the alkyl chain bridging the two carbonyl functions have little effect on the activity. One of the active compounds, N-(4-methoxy-benzoyl)-N'-[3-methylfuroxanyl-4-carbonyl)piperazine (17i) was tested for hypotensive effects on anaesthesized rats at 1.5 mg/kg, and found to demonstrate a gradual and sustained hypotensive effect. The results suggest that the furoxan-nicorandil derivatives are a useful lead in the design of NO-donor compounds for hypertension.     

Synthesis and structure of novel 3,4‐annelated coumarin derivatives

Condensation of 4‐chloro‐2‐oxo‐2H‐chromene‐3‐carbonitrile ( 1 ) with heteroarylamines 2a‐d in acetonitrile containing a catalytic amount of triethylamine followed by spontaneous intramolecular cyclization gave the novel coumarin derivatives 3a‐d , respectively. These compounds underwent acid hydrolysis giving the corresponding oxoderivatives 4a‐d . The structural assignments of the synthesized compounds were based on elemental, IR, ¹H and ¹³C NMR analyses.     

New crown annelated tetrathiafulvalenes: synthesis, electrochemistry, self-assembly of thiol derivatives, and metal cation recognition

The synthesis of new S(2)O(4)-crown annelated tetrathiafulvalene (TTF) derivatives substituted with one terminal thiol group is described. Self-assembled monolayers (SAMs) of these compounds have been assembled on gold and platinum surfaces, the latter substrate giving improved quality films. SAMs of TTF derivative 16b are the most stable of those we have studied. Electrochemical data for SAMs of 5a, 5b, 8, 16a, and 16b in acetonitrile reveal two reversible one-electron waves, typical of the TTF system; the current increased linearly with scan rate, indicating a surface wave response. SAMs of 8, 16a, and 16b exhibited an electrochemical response in aqueous electrolytes, which was observed between 50 and 100 cycles. Moreover, if the potential scanned was limited to the first TTF oxidation, the cyclic voltammetry response was observed for at least 1000 cycles. Metal complexation by the crown ionophore of the SAMs in acetonitrile has been monitored by a positive shift in the first oxidation potential of the TTF unit (maximum DeltaE(1)(1/2) = 80 mV for Ag(+)). We also report the X-ray crystal structure of TTF-crown derivative 21 bearing two hydroxymethyl substituents, synthesized during the course of this work. The structure is characterized by infinite chains of molecules linked by strong intrachain hydrogen bonds between the terminal hydroxy groups.     

Synthesis of furoxan derivatives based on 4-aminofuroxan-3-carboxylic acid azide

A convenient preparative method was developed for the synthesis of 4-amino-3-furoxancarboxylic acid azide, which is a universal synthon for the preparation of functional furoxan derivatives. This method was used for preparing new azo-, azoxy-, azido-, cyano-, nitro-, carbonylamino-, and hydroxylamino-substituted furoxan derivatives, which have earlier been difficultly accessible.     

Organometallic synthesis in the furazan series. 3. Silyl derivatives of methylfurazans

The reactions of (lithiomethyl)furazans with chlorosilanes were investigated and a number of silyl derivatives of methylfurazans were prepared. The reactivity of these compounds was studied.