Synthesis and some properties of benzo-1,2,3-thiaselenazolium salts

The reaction of selenious acid on benzo-1,2,3-dithiazolium salts (Herz salts) gives benzo-1,2,3-thiaselenazolium salts, which were previously obtained from o-aminothiophenols. This reaction, which involves exchange of sulfur by selenium in the heteroring, occurs only under conditions in which the products of hydrolysis of the Herz salts —benzo-3H-1,2,3-dithiazole 2-oxides- are in equilibrium with them.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1361–1364, October, 1976.     

Reactions of benzo-1,2,3-dithiazolium salts and their selenium analogs with amines

The corresponding 6-arylamino derivatives were obtained by reaction of 6-chloro, 6-bromo, and 6-methoxy derivatives of benzo-1,2,3-dithiazolium and their selenium analogs — benzo-1,2,3-thiaselenazolium, benzo-2,1,3-thiaselenazolium, and benzo-1,2,3-diselenazolium salts — with aromatic amines. The 6-methoxy derivatives also react with acetates of secondary aliphatic amines, whereas in the case of the chloro derivatives attack is directed to the heteroring. 6-Aryl(dialkyl)amino derivatives of dithiazolium and 1,2,3-thiaselenazolium salts are protonated in concentrated sulfuric acid at the exocyclic nitrogen atom. The analogous derivatives of 2,1,3-thiaselenazolium and diselenazolium salts under the same conditions form a tautomeric mixture of dications, the position of the equilibrium between which depends on the substituent. The electronic and PMR spectra of the amination products are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1499–1502, November, 1977.     

Structures and reactivities of benzo-1,2,3-dithiazolium salts and their selenium analogs

A number of benzo-1,2,3-dithiazolium chlorides (I) and their selenium analogs — benzo-1,2,3-thiaselenazolium, benzo-2,1,3-thiaselenazolium, and benzo-1,2,3-diselenazolium salts — were synthesized. The electronic structures and reactivities of the I cation and salts I–IV are discussed on the basis of a quantum-chemical calculation of cation I and the PMR spectra of salts I–IV. Successive substitution of the sulfur atoms in the I cation by selenium atoms, particularly in the 2 position, substantially increases the degree of transfer of positive charge to the condensed benzene ring. The trend of the nucleophilic reactivities of 6-methoxy derivatives of salts I–IV in the reaction with aromatic amines is the same as the trend of the degree of localization of the positive charge in the 6 position.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 912–916, July, 1978.     

Electroreduction of benzo-1,2,3-dithiazolium salts and their selenium analogs in nonaqueous solution

The electroreduction of benzo-1,2,3-dithiazolium cations and their selenium analogs in aprotic solvents takes place in two steps. The first step is a reversible, one-electron transfer leading to the formation of stable radicals detected by EPR. As a result of further electroreduction, the radicals obtained combine with six electrons to form the corresponding o-aminothio(seleno)phenols. Analysis of the reduction potentials of the compounds studied shows that the substitution of a selenium atom for a sulfur in these cations, especially in the 2 position of the heterocycle, facilitates their electrochemical reduction. The electrochemical activity and the kinetics of nulceophilic substitution in the cations studied are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–222, February, 1985.     

The preparation and characterization of 5-substituted-4-chloro-1,2,3-dithiazolium salts and their conversion into 4-substituted-3-chloro-1,2,5-thiadiazoles

A series of monosubstituted acetonitriles were treated with disulfur dichloride at room temperature in CH2Cl2 to afford 5-substituted-4-chloro-1,2,3-dithiazolium chlorides 1.Where the 5-substituent was not a good leaving group the chloride salts were converted into the corresponding perchlorate salts 2 which were sufficiently stable and soluble to provide both (1)H- and (13)C-NMR and cyclic voltammetry data. Several of the dithiazolium chlorides were converted into their corresponding 4-substituted-3-chloro-1,2,5-thiadiazoles 13 on treatment with aqueous ammonia. Mechanisms for all reactions are proposed.     

Reaction of N-acylthioureas with electrophilic reagents : Synthesis of 1,3,5-oxadiazinium salts, 1,3,5-thiadiazinium salts, 1,2,4-dithiazolium salts and benzothiazoles

N-Acylthioureas 1 can be easily transformed into 2,4-diamino-6-aryl-1,3,5-oxadiazinium salts 12, 2,4-diamino-6-aryl-1,3,5-thiadiazinium salts 13,3-amino-5-aryl-1,2,4-dithiazolium salts 19 and 2-acylimino-benzothiazolines 22, respectively by reaction with different electrophiles. The structure of the compounds prepared is confirmed by analytical data as well as by chemical transformations.     

Synthesis and properties of 4-substituted 5H-1,2,3-dithiazol-5-ylidenes

Substituted ethanone oximes react with S₂Cl₂ and pyridine to give 1,2,3-dithiazolium chlorides. The treatment of these products with malonodinitrile in dichloromethane affords 4-substituted 5 H-1,2,3-dithiazol-5-ylidenes. The reaction of the latter compounds with n-butylamine unexpectedly yielded addition products at one of the nitrile groups, viz. substituted 1,2,3-dithiazol-5-ylideneethanimidamides.     

2-氰基-3,4-二氢喹唑啉衍生物的合成

邻硝基苯甲醛与取代苯胺(1)或取代苄胺(2)进行还原氨化反应得N-(2-硝基苄基)取代苯胺(3)或N-(2-硝基苄基)取代苄胺(4);将3或4的硝基还原为氨基生成关键中间体N-(2-氨基苄基)取代苯胺(5)或N-(2-氨基苄基)取代苄胺(6);5或6分别与4,5-二氯-1,2,3-二噻唑氯化物进行缩合反应,合成了一系列新的2-氰基-3,4-二氢喹唑啉类衍生物,收率36%~72%,其结构经1H NMR和HR-MS确证。     

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.     

Two-component polymer films of palladium and fullerene with covalently linked crown ether voids: effect of cation binding on the redox behavior

Redox active films have been generated via electrochemical reduction in a solution containing palladium(II) acetate and fulleropyrrolidine with covalently linked crown ethers, viz., benzo-15-crown-5 and benzo-18-crown-6. In these films, fullerene moieties are covalently bonded to palladium atoms to form a polymeric network. Films show ability to coordinate alkali metal cations from the solution. Therefore, in solutions containing salts of alkali metal cations, benzo-15-crown-5-C₆₀/Pd and benzo-18-crown-6-C₆₀/Pd films are doped with cations coordinated by crown ether moiety and anions of supporting electrolyte which enter the film to balance positive charge. These films are electrochemically active in the negative potential range due to the reduction of the fullerene moiety. Reduction of the polymer is accompanied by the transport of supporting electrolyte ions between solution and solid phase. In solution containing alkali metal salts, the process of film reduction is accompanied by the transport of anions from the film to the solution. In the presence of tetra(alkyl)ammonium salts, transport of cations from the solution to the film takes place during the polymer reduction.     

Identification of [1,3]dithiolo[4,5-d]dithiazolyl radicals by in situ EPR spectroscopy and cyclic voltammetry

The synthesis of [1,3]dithiolo[4,5-d]dithiazolium salts from readily available zinc chelate has been developed. Chlorination of 2-oxo and 2-(dicyanomethylene) (2-oxo-1,3-dithiole-4,5-diyl) diethanethioates with SO₂Cl₂ followed by condensation with Me₃SiN₃ produced 1,2,3-dithiazolium chlorides. The structure of 5-(dicyanomethylene)[1,3]dithiolo[4,5-d][1,3,2]dithiazol-1-ium tetrafluoroborate was confirmed by powder X-ray diffraction, and its chemical bonding pattern as well as charge transfer were studied within the QTAIM framework applied to the results of plane wave DFT periodic calculations. Reduction with triphenylantimony and electrochemical reduction of [1,3]dithiolo[4,5-d]dithiazolium salts by cyclic voltammetry, chronoamperometry, and microelectrolysis at a controlled potential on a platinum electrode in acetonitrile revealed the formation of [1,3]dithiolo[4,5-d]dithiazolyl radicals, which were characterized by EPR spectroscopy.     

Synthesis of [(4-chloro-5H-1,2,3-dithiazol-5-ylidene)amino]azines

The reactions of 2-, 3- and 4-aminopyridines with 4,5-dichloro-1,2,3-dithiazolium chloride (Appel salt) 4 to give N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)pyridin-X-amines 1a (X = 2), 1g (X = 3) and 1k (X = 4) were optimized with respect to base, temperature and reaction time. Based on these conditions a total of thirteen [(dithiazolylidene)amino]azines 1a-m were prepared and fully characterized.     

The reaction of 4,5-dichloro-1,2,3-dithiazolium chloride with dimethylsulfonium dicyanomethylide: an improved synthesis of (4-chloro-1,2,3-dithiazolylidene)malononitrile

4,5-Dichloro-1,2,3-dithiazolium chloride 6 (Appel salt) reacts with dimethylsulfonium dicyanomethylide 11 to give 5-(4-chloro-1,2,3-dithiazolylidene)malononitrile 1 and a mixture of E/Z isomers of 3-(4-chloro-5H-1,2,3-dithiazol-5-ylideneamino)-3-chloro-2-(methylthio)acrylonitrile 13. The reaction of 4-chloro-5H-1,2,3-dithiazole-5-thione 10 with dimethylsulfonium dicyanomethylide 11 gives (dithiazolylidene)malononitrile 1 in 92% yield. All new compounds are fully characterised and rational mechanisms are proposed for the formation of all key compounds.     

1,2,3-Oxadiazole rings in the aromatic compounds: A quantum-chemical investigation

Quantum chemical method PBE0/cc-pVTZ in conjunction with the polarizable continuum model (PCM) was applied to the calculation of the equilibrium structural parameters of the benzene and naphthalene 1,2,3-oxadiazole derivatives, as well as relevant diazocarbonyl compounds both in the free state and dissolved in dichloromethane. The calculated ionization potentials of benzo-1,2,3-oxadiazole (9.49 eV), 6-diazocyclohexa-2,4-dien-1-one (8.16 eV) and (6-oxocyclohexa-2,4-dien-1-ylidene)carbonyl (8.34 eV) differ from the experimental values no more than by 0.09 eV. The calculations indicate the possible existence of naphtho [2,3-d:6,7-d′]bis(1,2,3-oxadiazole) in the gas phase and in aprotic solvents.     

Benzo-1,2,3-oxadiazole and 6-Diazocyclohexa-2,4-dienone: Structures and Relative Energies of Molecules

Structural parameters, IR spectra, ionization potentials, relative energies, isomerization barriers, and solvation energies have been calculated for the aromatic benzo-1,2,3-oxadiazole (prevalent tautomer in the gas phase) and zwitterionic 6-diazocyclohexa-2,4-dienone (prevalent tautomer in a polar solvent) molecules. Similar calculations indicated that unsubstituted 1,2,3-oxadiazole is unstable in all solvents.Original Russian Text Copyright © 2004 by S. G. Semenov and Yu. F. Sigolaev__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1128–1131, November–December, 2004.     

Synthesis of Substituted and Condensed Tetrahydrospiro[benzo-2-azepinecyclohexanes] from 1-Cyano- and 1-Carbamoyl-5-methyl-4,5-dihydro-3H-spiro[benzo-2-azepine-3,1′-cyclohexanes]

Substitution of the nitrile group by hydroxylamine and hydrazine has been effected in 1-cyanodihydrospiro[benzo-2-azepine-3,1′-cyclohexane]. From the 1-cyano and 1-hydrazino derivatives tetrahydrospiro{1,2,3- and 1,2,4-triazolo[5,1-a]benzoazepine-5,1′-cyclohexanes} have been obtained. It was established that 1-carbamoyldihydrospiro[benzo-2-azepine-3,1′-cyclohexanes] are converted under the conditions of the Hoffmann reaction into spiro{diaziridino[3,1-a]benzo-2-azepine-3,1′-cyclohexane{, and is reduced by sodium borohydride to the tetrahydro derivative. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1033–1037, July, 2005.     

Bond orders and electron delocalization indices for S–N,S–C and S–S bonds in 1,2,3-dithiazole systems

A parametric QTAIM-based (topological) model of bond orders and a modification of the Pauling bond order model are proposed for N,S-containing heterocycles, in particular, for 1,2,3-dithiazoles and 1,2,3-dithiazolium systems, which are prone to the formation of stable radicals and therefore are promising compounds in photovoltaics. These models have been parameterized for covalent S–N, S–C and S–S bonds using the electron delocalization indices. A modified Pauling’s bond order model uses turning radii, that is, the distances within which the potential acting on an electron in a system still tends to return that electron to the atomic basin, and avoids the need to choose the hybridization state of bound atoms arbitrarily.     

The reaction of 4,5-dichloro-1,2,3-dithiazolium chloride with DMSO: an improved synthesis of 4-chloro-1,2,3-dithiazol-5H-one

4,5-Dichloro-1,2,3-dithiazolium chloride 2 (Appel salt) reacts with either DMSO, diphenylsulfoxide 11 or methylphenylsulfoxide 12 to give 4-chloro-5H-1,2,3-dithiazol-5-one 1 in excellent yields. The use of catalytic amounts of DMSO (1 mol %) in MeCN in the presence of water (1 equiv) transforms Appel salt 2 into dithiazolone 1 in near quantitative yields (92%). Rational mechanisms are proposed to explain the catalytic nature of these reactions.     

A rapid and convenient synthesis of novel 1-imino-2,3-dihydro-1H-pyrazino[2,1,-b]quinazolin-5-ones

Exploring original approaches for the synthesis of therapeutic agents having a quinazoline part, we discovered that novel 3,4-dihydro-2H-pyrazino[2,1,-b]quinazolines (3) may be rapidly and easily obtained via the chemistry of 4,5-dichloro-1,2,3-dithiazolium chloride (1). Our synthetic approach of this reaction is described with the aim of obtaining a well-controlled access to this very rarely described pyrazino[2,1,-b]quinazoline skeleton.     

Novel synthesis and reactions of 5,7-dialkyl-4,6-dioxo-4,5,6,7-tetrahydro- isothiazolo[3,4,-d]pyrimidine-3-carbonitriles and 6-methyl-4-oxo-4H-1-aza-5-oxa-2- thiaindene-3-carbonitrile

[reaction: see text] 5,7-Dialkyl-4,6-dioxo-4,5,6,7-tetrahydroisothiazolo[3,4-d]pyrimidine-3-carbonitriles 4, prepared from 6-amino-1,3-dialkyluracils 3 and 4,5-dichloro-5H-1,2,3-dithiazolium chloride (Appel's salt) 1, are utilized for the preparation of new derivatives of 4 bearing amino, alkylthio, amido, thioamido, tetrazolyl, and carboximidic acid ethyl ester groups at position 3. Similarly, the reactions of 6-methyl-4-oxo-4H-1-aza-5-oxa-2-thiaindene-3-carbonitrile 8, prepared from 4-amino-6-methyl-2-pyrone 6 and 1, with alkyl- and arylamines in DMF at 50 degrees C and reflux afforded different isothiazole derivatives 11 and 17, respectively. On the other hand, treatment of 8 with 1,3-diaminopropane in THF at room temperature, followed by chromatography on silica gel, gave 3-(2-oxopropyl)-6,7,8-trihydro-4H-1-thia-2,5,9-triazacyclopentacyclononene-4,10-dione 12 in 59% yield.