Acidic hydrolysis of N-acyl-1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes

Acidic hydrolysis of N-acyl 1-methyl- and 1-phenyl-3-amino-1,2-dicarba-closo-dodecaboranes has been studied. It has been shown that acidic hydrolysis of diastereomeric amides of 1-methyl-3-amino-1,2-dicarba-closo-dodecaborane results in the partial racemization of the target 3-amino-1-methylcarborane. Under the similar conditions, the hydrolysis of N-acyl-3-amino-1-phenyl-1,2-dicarba-closo-dodecaboranes resulted in amide bond cleavage accompanied by simultaneous deboronation with the removal of boron atom at position 6 of carborane cage and formation of 7,8-dicarba-nido-undecaborane derivative according to ¹¹B and ¹H NMR spectroscopy.     

Electrochemical Reduction of 1,2-Di（p-tolylimino）ethane and 1,2-Di（2,4-dimethylphenylimino）ethane in Dimethylformamide

1,2-Di（p-tolylimino）ethane （Ⅰ） and 1,2-Di（2,4-dimethylphenylimino）ethane （Ⅱ） were synthesized and their electrochemical behavior investigated in dimethylformamide using classical voltammetry, differential pulse voltammetry, cyclic voltammetry, chronoamperometry, controlled potential electrolysis and coulometry. Both bis-Schiff base ligands examined show a cathodic irreversible peak which corresponds to one-electron reduction of the substrate to form anion radical. According to the fact obtained from cyclic voltammetry, that the current function （ip/v^1/2） is a decreasing function of the scan rate, it can be concluded that there is a following coupling chemical reaction （EC mechanism）. Thus, the most probable mechanism of electroreduction of both ligands is the coupling of two radicals to form a dimer.     

Synthesis of dialkoxy- and alkoxy-amino-disubstituted derivatives of B12H12 2−

Dichloromethoxymethane reacts with the sodium salt ofcloso-dodecahydrododecaborate Na₂B₁₂H₁₂ to give disubstituted cluster, which readily decomposes when treated with various reagents. This cluster reacts with water, forming the previously described 1,7-B₁₂H₁₀(OH)_{2 2–}reaction with alcohols results in a novel 1,7-dialkoxy derivative, whereas interaction with morpholine in acetone solution affords the novel anion, 1-O-I-Prⁱ-7-O(CH₂CH₂)N-B₁₂H₁₀ ^2–. All of these derivatives were isolated as cesium salts and characterized by one- and two-dimensional NMR techniques.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 421–424, March, 1995.     

Electrochemical transformations of cycloheptatriene derivatives

Redox reactions of a series of substituted cycloheptatrienes are studied on a platinum electrode in acetonitrile using the cyclic voltammetry method. It was found that heptaphenyl-substituted cycloheptatrienes are irreversibly oxidized in two stages in the range of high anodic potentials to form unstable radical cations and dications. As opposed to the unsubstituted and monosubstituted cycloheptatrienes, they are not reduced at the potentials higher than ?2 V (SCE). A new stable radical anion was found in the reduction of N-cycloheptatrienylphthalimide. Its spin density distribution is studied by ESR spectroscopy.     

1D and 2D supramolecular structures of silver carborane dicyclohexylphosphine complexes constructed by C-H?H-B dihydrogen bonding interactions

Five new carborane dicyclohexylphosphine complexes, [Ag₂(μ-I)₂{1,2-(P Cy₂)₂-1,2-C₂B₁₀H₁₀}₂] (1), [Ag₂(SCN)₂{1,2-(PCy₂)₂-1,2-C₂B₁₀H₁₀}₂]_n·CH₂Cl₂ (2), [Ag(ClO₄){1,2-(PCy₂)₂-1,2-C₂B₁₀H₁₀}]·CH₂Cl₂ (3), [Ag₂(μ-NO₃)₂{1,2-(PCy₂)₂-1,2-C₂B₁₀H₁₀}₂]·CH₂Cl₂ (4) and [Ag(SC₆H₄COOH){1,2-(PCy₂)₂-1,2-C₂B₁₀H₁₀}₂]·CH₂Cl₂ (5), have been synthesized by the reactions of 1,2-bis(dicyclohexylphosphino)-1,2-dicarba-closo-dodecaborane with AgX (X = I, SCN, ClO_4, NO₃ and SC₆H₄COOH) in CH₂Cl₂. The structures of the five complexes were characterized by elemental analysis, FT-IR, ¹H, ¹³C, ¹¹B and ³¹P NMR spectroscopy. X-ray structure analysis revealed that the structures of the complexes can be classified into three types. Complexes 1 and 4 are di-μ-X-bridged structures and complexes 3 and 5 are mononuclear structures, while complex 2 is a chain-like polymer. Complexes 1 and 2 form 2D supramolecular networks and complexes 3, 4 and 5 form 1D chains via C-H?H-B dihydrogen bonding interactions.     

Addition compounds of nucleophiles and 3-ethylthio-6-oxo-6H-1,2-dithiolo[4,3-c]1,2-dithiolium tetrafluoroborate. Synthesis of 3H,6H-1,2-dithiolo[4,3-c]1,2-dithiole-3-one-6-thione

Summary A smooth method of synthesizing 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3,6-dithione (3), and also its partial desulfuration to yield 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3-one-6-thione (4) is presented. The ethylation product5 of the monothione4 reacts with various nucleophilic reagents to form remarkably stable adducts. The adducts of5 with methanol,tert-butyl mercaptan, and with aniline could be isolated and characterized by their¹H-NMR spectra.

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Anlagerungsverbindungen von Nukleophilen an 3-Ethylthio-6-oxo-6H-1,2-dithiolo[4,3-c]1,2-dithioliumtetrafluoroborat. Synthese von 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion

Zusammenfassung Eine glatte Synthese für 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3,6-dithion (3) und für dessen partielle Entschwefelung zu 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion (4) wird angegeben. Das Ethylierungsprodukt5 des Monothions4 reagiert mit unterschiedlichen Nukleophilen zu bemerkenswert stabilen Addukten. Die Addukte mit Methanol,tert.-Butylmercaptan und mit Anilin wurden isoliert und durch ihr¹H-NMR-Spektrum charakterisiert.

     

Synthesis and study of new 2-aryl-1-(4-nitrophenyl)-1,1a-dihydroazireno[1,2-a]quinoxaline derivatives

New derivatives of photochromic 2-aryl-1-(4-nitrophenyl)-1,1a-dihydroazireno[1,2-a]quinoxalines were synthesized by condensation of 4-methyl-and 4,5-dimethyl-1,2-phenylenediamine with 1,3-diaryl-2,3-dibromopropan-1-ones. The reactions of 4-methyl-1,2-phenylenediamine produce mixtures of regioisomers. The chemical properties of the reaction products were studied. The structure of one of the latter was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–356, February, 2006.     

Electrochemical study of 1,2-Naphthoquinone-4-sulphonate and 1,2-Naphthoquinone semicarbazone

Summary A study of the electrochemical characteristics of 1,2-naphthoquinone-4-sulphonate, sodium salt, and of the semicarbazone of 1,2-naphthoquinone (Naftazone) was carried out using d.c., a.c. and d.p. polarography and cyclic voltammetry. Changes in the waves as a function of concentration and pH indicate evidence of adsorption phenomena at the potential of the reduction wave. These techniques also indicate the formation of a mercury derivative in the case of Naftazone. The quantitative determination of these two compounds is possible by polarography. Limits of detection are 5×10^–6 and 5×10^–8 M, respectively.

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Elektrochemische Untersuchung von 1,2-Naphthochinon-4-sulfonat und 1,2-Naphthochinon-semicarbazon

Zusammenfassung Die elektrochemischen Eigenschaften von 1,2-Naphthochinon-4-sulfonat und -semicarbazon (Naftazon) wurden mit Hilfe der Gleichstrom-, Wechselstrom und Differentialpuls-Polarographie sowie der cyclischen Voltammetrie untersucht. Veränderungen an den Stufen in Abhängigkeit von Konzentration und pH-Wert deuten auf Adsorptionsvorgänge beim Potential der Reduktionsstufe hin. Im Falle von Naftazon wurde die Bildung eines Quecksilberderivats nachgewiesen. Beide Substanzen können polarographisch mit Nachweisgrenzen von 5×10^–6 bzw. 5 × 10^–8 M bestimmt werden.

     

Electrochemical study of the nitroxyl radical derivatives built in the π-conjugated poly(phenylenevinylene) skeleton

The electrochemical oxidation and reduction of the stable neutral nitroxyl radical gave the oxoaminium salt and hydroxylamine or nitroxyl anion, respectively. The electrochemical behavior of the N-butylnitroxyl radicals or N-butylhydroxylamines built in to various phenylenevinylene species were discussed in connection with its developed π-conjugated structure based on cyclic voltammetric measurements. The aromatic nitroxyl radical showed two pairs of oxidation–reduction waves, but the acidic proton (hydroxylamine) changed its cathodic peak to a broad one with a shift to the anodic side. The π-conjugated poly(phenylenevinylene) backbone and mobile proton of the hydroxylamine unstabilized the nitroxyl radical by retaining the energy gap.     

1,2-Benzisoxazole-3-acetamide derivatives as dual agents for DPP-IV inhibition and anticancer activity

Abstract

Herein, we have designed various benzisoxazole acetamide derivatives with and without glycine spacer as DPP-IV inhibitors. Compounds 9a–d and 11a–e were synthesized and screened for their in vitro DPP-IV inhibition. Compounds 11a and 11c showed moderate activity for DPP-IV inhibition, whereas other remained inactive at 25–200?µM concentrations. DPP-IV inhibition can be a good strategy for modulating diabetes and cancer; hence, we have screened compounds 9a–d and 11a–e for their anticancer activity using MTT assay against A549 and MCF7 cell lines. Compounds 9a–d without glycine spacer have shown good anticancer activity compared to compounds 11a–e with glycine spacer. Compound 9b has shown moderate activity with IC₅₀ values 4.72?±?0.72 and 4.39?±?0.809?µM against A549 and MCF7 cell lines, respectively. Interestingly, compound 9c with cyano group has shown very good anticancer activity with IC₅₀ 2.36?±?0.34?µM against MCF7 cell line as compared to fluorouracil with IC₅₀ 45.04?±?1.02?µM.     

Electrochemical Reduction of 5-Oxoindeno[1,2-b]pyridinium Perchlorates in the Presence of Alkylating Agents

It was established that 9b-substituted 5,9b-dihydroindenopyridines are formed in addition to the reduction products on preparative electrochemical reduction of 5-oxoindeno[1,2-b]pyridinium perchlorates at a mercury electrode in acetonitrile in the presence of alkylating agents.     

Synthesis and NMR spectra of the hydroxyundecahydro-closo-dodecaborate [B12H11OH]2− and its acylated derivatives

Tetrabutylammonium hydroxyundecahydro-closo-dodecaborate was obtained in high yield via [B₁₂H₁₁NMP]^–(NMP =N-methylpyrrolidone) by the modified method. [B_i2H₁₁OH]^2– is easily acylated by aromatic acyl chlorides to give novel compounds [B₁₂H₁₁OCOAr]^2– in high yields. All the compounds were characterized by standard and special NMR methods.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 722–725, March, 1996.     

Pyrolysis of 3-hydroxy-2-arylhydrazonoalkanoic acid derivatives

1,2-Diaza-1,3-butadienes have been obtained from readily available 3-hydroxy-2-arylhydrazonopropanoates under various reaction conditions including pyrolysis, dehydration under Mitsunobu conditions or with acetic anhydride or acetic acid. According to their method of synthesis these 1,2-diaza-1,3-butadienes underwent subsequent reactions to give interesting products, and in the presence of proper dienophiles gave the corresponding cycloaddition products. Also, a new approach to pyrazole-3-carboxylic acid derivatives was discovered during an attempt to dehydrate 3-hydroxy-2-arylhydrazonobutanoic esters.     

Synthesis and characterization of three nickel(ii) carborane complexes containing nido- or closo-carborane diphosphine ligand

Three nickel(II) carborane complexes, [Ni₂(μ-Cl)₂{7,8-(PPh₂)₂-7,8-C₂B₉H₁₀}₂] (1), [Ni{7-(OPPh₂)-8-(PPh₂)-7,8-C₂B₉H₁₀}{7,8-(PPh₂)₂-7,8-C₂B₉H₁₀}] (2) and [NiBr₂{1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀}] · CH₂Cl₂ (3), have been synthesized by the reactions of 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane with NiCl₂ · 6H₂O or NiBr₂ · 6H₂O in ethanol under different conditions, respectively. For complex 1, it could also be obtained under the solvothermal condition. All the three complexes were characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR spectroscopy and X-ray structure determination. Single crystal analysis shows that the molecular symmetry of complex 1 is centrosymmetric, containing two same structure units - Ni(7,8-(PPh₂)₂-7,8-C₂B₉H₁₀) linked by two bridged-Cl atoms. The central square plane formed by the [Ni₂Cl₂] unit is almost parallel to the two side NiPP planes. For complex 2, the coordination environment of the Ni atom is a seriously distorted square-planar, in which two positions come from the chelating diphosphine ligand [7,8-(PPh₂)₂-7,8-C₂B₉H₁₀]⁻ degraded from the closo species, while the other two are occupied by an unsymmetrical chelating phosphine oxide ligand [7-(OPPh₂)-8-(PPh₂)-7,8-C₂B₉H₁₀]⁻. As for complex 3, the geometry at the Ni atom is a slightly distorted square-planar. The closo carborane diphosphine ligand 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀ was coordinated bidentately to the metal ion through the two phosphorus atoms, and the two Br atoms are at cis position which can fulfill the four coordination mode of the metal.     

不同离子液体中三氯化铁的电化学行为

本文采用循环伏安法研究了FeCl3在五种不同的离子液体(包括疏水性和亲水性的离子液体)中的电化学行为,计算了不同离子液体中FeCl4的扩散系数.实验结果表明:Fe3+在离子液体中的氧化还原过程是一个具有较高可逆性的扩散控制过程.离子液体的阴、阳离子的结构及大小对Fe3+的电化学响应有影响,且离子液体的阴离子的影响较阳离子更大一些.     

Sonogashira cross-coupling of 3-bromo-1,2-diones: an access to 3-alkynyl-1,2-diones

A new general method for the synthesis of enols of cyclic 3-alkynyl-substituted 1,2-diketones is developed. Sonogashira cross-coupling of silyl enolates of cyclic 3-bromo-cyclopentane- and 3-bromo-cyclohexane-1,2-diones with variety of substituted acetylenes afforded enols of cyclic 3-alkynyl-1,2-diones with good yields (up to 93%) in a short reaction time. The starting 3-bromo-1,2-diones are easily obtainable by direct bromination of 1,2-diones with NBS.     

Electrochemical synthesis of diaminodicarboxylic acid derivatives

Diaminoadipic acid derivatives were synthesized in good yields by electrolysis of N,N-diacyldehydroalanines. Cyclic voltammetry measurements on the precursors are presented and interpreted as supporting formation of a nucleophilic intermediate generated by electrochemical reduction.     

Electrochemical reduction of some 3-aryl-2-cyanothioacrylamide derivatives at the DME

Summary The polarographic behaviour of the title compounds is reported and discussed in acid media. The obtained data indicate that these compounds undergo a four-electron reduction. A mechanism for the electrode process atpH<7 is proposed, discussed and clarified via identification of controlled potential electrolysis (CPE) product and application of cyclic voltammetry (CV).

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Die elektrochemische Reduktion einiger 3-Aryl-2-cyanothioacrylamid-Derivate an der DME

Zusammenfassung Es wurde das polarographische Verhalten der Titelverbindungen in saurem Medium untersucht. Die erhaltenen Daten zeigen, daß diese Verbindungen eine Vierelektronenreduktion eingehen. Es wird ein Mechanismus für den Elektrodenprozess beipH<7 vorgeschlagen und diskutiert. Zur Klärung der Verhältnisse wurden die mittels kontrollierter Potential-Elektrolyse (CPE) erhaltenen Produkte identifiziert und auch cyclische Voltammetrie eingesetzt.