1-(Trimethylsilyl)-1,2,4-triazene: A Novel Free Radical Initiator

The reaction of 1-(trimethylsilyl)-1,2,4-triazene with trifluoromethylsulfenyl chloride in dry n-pentane furnishes a complex mixture containing 11 compounds. All but six of them are derived from the reaction of the thiyl or chlorine radicals with n-pentane. The probable mechanism of their formation and mass spectral characterization are presented in this article.     

S-, S,S-, S,S,S- Und N,S-Substituierte Dienverbindungen Und Dibutadienylpiperazinverbindungen Von 2-Nitropentachlorbutadien

Nitrodiene compound 1 was stirred with allylthiol for a long time and compound 3 was obtained. Compound 1 gave bis(thio)substituted 2-nitrodiene compound 4 and tris(thio)substituted 2-nitrodiene compound 5 with 2 moles allylthiol in the presence of NaOH in ethanol. Mono(allylthio)substituted diene compound 3 gave dibutadienyl substituted piperazine compounds with piperazine 6 in CH 2 Cl 2 (or diethylether). Compound 3 gave compound 9 with compound 8 . Compounds 11a-e have been obtained from the reaction of compound 3 with compounds 10a-e . Nach langem Rühren von der Verbindung 1 mit Allylthiol entsteht die Verbindung 3 . Die Verbindung 1 liefert mit zwei Mol von Allylthiol in ethanolischer Natronlunge die bis(thio)substituierte 2-Nitrodienverbindung 4 und tris(thio)substituierte Dienverbindung 5 . Mono(allylthio)substituierte Dienverbindung 3 ergibt mit Piperazine in CH 2 Cl 2 (oder in Ether) die dibutadienylsubstituierte Piperazinverbindung 7 . Die Verbindung 3 liefert mit der Verbindung 8 die Verbindung 9 . Durch die Reaktion von der Verbindungen 10a-c wurden die Verbindungen 11a-e erhalten.     

Einige Neue N,S-Substituierte 2-Nitrodienverbindungen Aus Reaktionen Von Mono(p-fluorarylthio)substituierten Dienen Mit Aminen

2-Nitrodiene compound 1 was stirred with p-fluorothiophenol for a long time and compound 3 was obtained. Compound 1 gave bis(thio)substituted 2-nitrodiene compound 4 and tris(thio)substituted compound 5 with 2 moles of p-fluorothiophenol in the presence of NaOH in ethanol. The compounds 9a–g have been prepared from 8a–g and 3. Compound 7 was obtained from the reaction of mono(thio)substituted 2-nitrodiene with morpholine. Compound 3 gives 11a–d in the reaction with piperidines in CH₂Cl₂ (or ether). Compound 13a–b have been obtained from the reaction of compound 3 with primary amines 12a–b. Compound 3 gives 15 and 16 in the reaction with 2,5-dimethylpiperazine in CH₂Cl₂.

     

Approaches to the preparation of (Z)-1,2-difluorostilbenes

Methodology directed at the preparation of (Z)-1,2-difluorostilbenes has been evaluated. For symmetrical (Z)-1,2-difluorostilbenes, photochemical isomerization of the isomeric (E)-1,2-difluorostilbenes, and HPLC separation of the mixture of stilbene isomers is a reasonable route to a particular (Z)-stilbene. An alternative approach to both symmetrical and/or unsymmetrical (Z)-1,2-difluorostilbenes has been developed via stereospecific Pd(0) coupling of (E)-1,2-difluoro-aryl-ethenyltributylstannanes under Stille-Liebiskind conditions with aryl idodies. The requisite arylstannanes can be obtained via the reported route developed by Davis or via (E)-1,2-difluorovinyltributylstannane - a new route described in this work. The methodology tolerates almost any functionality in the aryl ring, is easily carried out, is stereospecific and provides the first general route to (Z)-1,2-difluorostilbenes.     

Monophthalates with Oxidized C5-Carbon in the Ester Chain: A Simple Synthetic Access to Two Major Metabolites of Bis-(2-ethylhexyl)-phthalate

Summary.  The synthesis of two oxidized metabolites of bis-(2-ethylhexyl)-phthalate is described. The target structures were obtained by esterification of the appropriate alcohol carrying a protected hydroxy group with phthalic anhydride, followed by deprotection and further oxidation. Received February 26, 2002. Accepted March 6, 2002     

Total synthesis of bis-（2,3-dibromo-4,5-dihydroxyphenyl）-methane as potent PTP1B inhibitor

Protein tyrosine phosphatase 1B （PTP1B） plays an important role as a negative regulator and has been proved to be an effective target for the treatment of type 2 diabetes mellitus. Bis-（2,3-dibromo-4,5-dihydroxyphenyl）-methane 7 was first reported as a natural bromophenol with significant inhibition against PTP1B which was isolated from red algae Rhodomela conrervoides. Intrigued by its astonishing activity （IC50 = 2.4 μmol/L）, compound 7 was synthesized with the overall yield of 24% and evaluated for its PTPIB inhibitory activity compared with natural compound.     

Synthesis and Reactions of a Stable Precursor to Dienes Containing Both Silicon and Sulfur Substituents

3-(Phenylthio)-4-(trimethylsilyl)-3-sulfolene (2) was readily prepared by chlorosulphenylation-dehydrochlorination of 3-(trimethylsilyl)-3-sulfolene (4b) . Treatment of 2 with n-butyllithium at ?105 °C followed by an alkylating agent gave only C5 alkylation products 6 demonstrating the stronger carbanion stabilizing ability of phenylthio group than that of trimethylsilyl group. 2-(Phenylthio)-3(trimethylsilyl)-1,3-butadiene (3a) was readily prepared by thermal extrusion of sulfur dioxide from 2 . Selective oxidation of 3a with MCPBA gave the sulfinyl (3b) and sulfonyl (3c) derivatives. The Diels-Alder reactions of 3a-c were studied, and the regiocontrolling power of the substituents follows the order PhS >PhSO ～ PhSO₂ >Me₃Si.     

α-Diimine Cisplatin Derivatives: Synthesis,Structure, Cyclic Voltammetry and Cytotoxicity

Three new Pt(II) complexes [(dpp-DAD)PtCl₂] (I), [(Mes-DAD(Me)₂)PtCl₂] (II) and [(dpp-DAD(Me)₂)PtCl₂] (III) were synthesized by the direct reaction of [(CH₃CN)₂PtCl₂] and corresponding redox-active 1,4-diaza-1,3-butadienes (DAD). The compounds were isolated in a single crystal form and their molecular structures were determined by X-ray diffraction. The purity of the complexes and their stability in solution was confirmed by NMR analysis. The Pt(II) ions in all compounds are in a square planar environment. The electrochemical reduction of complexes I–III proceeds in two successive cathodic stages. The first quasi-reversible reduction leads to the relatively stable monoanionic complexes; the second cathodic stage is irreversible. The coordination of 1,4-diaza-1,3-butadienes ligands with PtCl₂ increases the reduction potential and the electron acceptor ability of the DAD ligands. The synthesized compounds were tested in relation to an adenocarcinoma of the ovary (SKOV3).     

Reactions of chromium and molybdenum carbonyls with bis-(salicylaldehyde)-1,3-propylenediimine Schiff base

Interaction of a Schiff base, bis-(salicylaldehyde)-1,3-propylenediimine, salpenH₂, with M(CO)₆ (M?=?Cr or Mo) in the presence of oxygen gave the oxo-complexes[M(O)(salpen)]. Magnetic studies for the two oxo-complexes showed chromium and molybdenum in the +4 formal oxidation state. In presence of pyridine, reaction of Cr(CO)₆ with salpenH₂ gave the identical product; [Cr(O)(salpen)]. Reaction of Mo(CO)₆ with salpenH₂ in presence of pyridine (py) resulted in formation of the square-pyramidal complex [Mo(py)(salpenH₂)]. Reactions of M(CO)₆ with salpenH₂ in presence of a ligand L (L?=?bipyridine (bpy) or 3,3-dimethylbipyridine (dmbpy)) gave the octahedral complexes [M(L)(salpenH₂)]. All the complexes were characterized by elemental analyses, IR, mass and ¹H NMR spectroscopy. The spectroscopic studies revealed the proposed structures. UV-Vis spectra of the ligand and its complexes in DMSO exhibited visible bands due to metal-to-ligand or ligand-to-metal charge transfer.     

N,S-Substituted Dienes from Mono(arylthio)substituted- and S-, S,S-Substituted Dienes

Mono(thio)substituted dienes 1a-1b gave compounds 3a-c and 5d-g with piperazine and piperidine derivatives in dichloromethane. Compounds 8 , 9 , and 10 were obtained from the reactions of perchlorobutadiene ( 6 ) with 1,4-butanedithiol ( 7 ) in ethanol in the presence of sodium hydroxide. Compounds 12a-b , 13a-b were obtained from the reactions of perchlorobutadiene ( 6 ) with allylmercaptan (CH 2 =CH--CH 2 --SH) and mercaptoethanol (HO--CH 2 --CH 2 --SH).     

吡啶双亚胺酰氯Ni(Ⅱ)配合物的合成、 表征及催化合成液体聚丁二烯

合成了一系列吡啶双亚胺酰氯三齿Ni(Ⅱ) 配合物(1a~1c, 2a~2c), 通过傅里叶变换红外光谱和元素分析对配合物进行表征, 测定了配合物1a~1c的晶体结构. 3个化合物同属于单斜晶系, 且都具有以Ni原子为中心的近似于C_s对称的扭曲三角双锥构型. 该系列配合物通过倍半乙基氯化铝(EASC)活化, 在20 ℃下对丁二烯聚合表现出良好的催化活性, 得到分子量为4700~5200、 cis-1,4含量为74.8%~77.2%(摩尔分数)的液体聚丁二烯. 通过改变配体的结构和聚合条件, 可在一定范围内调控聚丁二烯的结构和分子量.     

An approach to synthesis of (Z)-2-chloro-1,3-diarylpropen-1-ones by Vilsmeier reagent (bis-(trichloromethyl) carbonate/DMF)

A series of(Z)-2-chloro-1,3-diarylpropen-1-ones were unexpectedly synthesized in moderate yields by treatment of easily available 2,3-epoxy-1,3-diarylpropan-1-ones with Vilsmeier reagent,which was derived from bis(trichloromethyl) carbonate(BTC, triphosgene) and DMF.A possible mechanism was also proposed,where sequential ring-opening,halogenation and elimination reactions were involved.     

The ligand-ligand and spin-orbit interactions in Fe(phen) 3 +2 and Ru(phen) 3 +2 ions

To explain the differences in the spectral properties of the complex ions (–)-Fe(phen) ₃ ⁺² and (–)-Ru(phen) ₃ ⁺² the interaction between the ligands and spin-orbit coupling energies have been calculated. It is shown that the spinorbit coupling energy in case of Ru(II) complex is more important than the ligand-ligand interaction. This leads to a sequence of the lowest excited states ³A₂<¹A₂<¹E.     

The rotatory strengths of the electron-transfer transitions of the Tris-(1,10-phenanthroline)ruthenium(II) ion

In the present paper the rotatory strengths of the electron-transfer transitions observed in the spectrum of the complex ion (–)-Ru(phen)₃ ⁺² (phen = 1,10-phenanthroline) have been calculated theoretically. In the development of the calculation the coupled chromophore model has been used.     

Purins,pyrimidines, and related condensed systems. 22. Synthesis and heterocyclization of 7-alkynyl- and 6,7-dialkynyllumazines

The reaction of 6,7-dichloro-1,3-dimethyllumazine with terminal alkynes under Sonogashira conditions gave 7-alkynyl-6-chloro- and 6,7-dialkynyl-1,3-dimethyllumazines. It was found that the alkynyllumazines readily add primary and secondary alkylamines at the 7-alkynyl group to form stable enamines, hydrolysis of which gives 7-(-hydroxyvinyl)lumazines. The heterocyclization of 7-(-aminovinyl)- and 7-(-hydroxyvinyl)lumazines has been carried out to give pyrrolo-, pyrido-, furo-, and pyranopteridines.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 140–152, January, 2005.     

Quinoxaline-2,3(1H,4H)-dithione: Synthesis and reactions

Quinoxaline-2,3(1H,4H)-dithione can be synthesized efficiently through the thionation of quinoxaline-2,3(1H,4H)-dione with phosphorous pentasulfide. It can also be obtained by reaction of 2,3-dichloroquinoxaline with thiourea or sodium hydrogen sulfide. The most common reactions of quinoxaline-2,3(1H,4H)-dithione involve deprotonation and electrophilic attack at the sulfur atoms to give various substituted derivatives and poly-fused heterocyclic ring systems. The current review aims to provide a survey of the developments in quinoxaline-2,3(1H,4H)-dithione chemistry until 2016.     

Macrolactones built from the bis-3,4(indol-1-yl)maleimide scaffold

15, 16, and 17-Membered lactones based on the bis-3,4(indol-1-yl)maleimide framework were obtained using intramolecular esterification reaction starting from 3-(1-ω-carboxyalkyl-2,3-dihydroindol-1-yl)-4-(1-ω-hydroxyalkyl-2,3-dihydroindol-1-yl)-maleimides. 3,4-Dibromo-maleimide, ω-(2,3-dihydroindol-3-yl)alkanoic acids, and ω-(2,3-dihydroindol-3-yl)alkanoles were used as starting compounds. Substitution of Br for the substituted indolines followed by the intramolecular cyclization of O-silylated hydroxyl acids derivatives led to macrolactones that incorporated 4-(dihydroindol-1-yl)-3-(indol-1-yl)maleimide moieties. Indoline nuclei in these compounds were dehydrogenated by DDQ in refluxing toluene to give 15, 16 or 17-membered lactones 3-[(ω-3-carboxyalkylindol-1-yl)-4-(ω-hydroxyalkylindol-1-yl)maleimides. Quantum chemical calculations showed that the formation of macrolactones of smaller size (13-membered) corresponds to the higher Gibbs energy ΔG^# and correlates with the absence of the target reaction product.     

Structural studies of Cu(II) binding to the novel peptidyl derivative of quinoxaline: N-(3-(2,3-di(pyridin-2-yl)quinoxalin-6-yl)alanyl)glycine

The coordination properties of the novel conjugate towards copper ions were investigated. The performed studies exhibited the unusual binding properties of the ligand molecule having two potential strong coordination sites, namely dipeptidic chain and pyridyl nitrogens. On the basis of potentiometric and spectroscopic studies the binding at the low pH values to the aromatic entity is suggested, while the rise of pH (including physiological one) yielded the dimeric head-to-tail complex formation. This stable species possesses three nitrogen donors involved in Cu(II) chelation: N(pirydyl), NH₂ and N⁻(amide).     

ELECTRONIC AND LIGAND STRUCTURE DICTATED EFFECTS FOR TRIGONAL,TETRAGONAL AND RHOMBIC SYMMETRIES OF TRANSITION METAL CAGE COMPLEXES

Abstract

Spectroscopic and structural data of series of complexes with widely varied metal centers (d⁰ to d¹⁰) and an identical ligand sphere (figure) are presented. The structures comprise a range from near octahedral to near trigonal prismatic geometries and also involving additional small tetragonal perturbations. The complete series allows for an analysis of the various influences, viz. bonding and non-bonded interactions which dictate the compromise structure. Axial and rhombic distortions in solution and solid state of selected examples are discussed on the basis of electronic and EPR spectroscopy and trigonal distortions are analyzed on the basis of twist angles calculated from X-ray data.