Synthese und reaktionen von element-IVB-substituierten stannacyclohexadienderivaten

Metallation of 1,1-dibutyl-1-stannacyclohexadiene-2,5 (I) with lithiumamides yield the lithium compound II, from which the trimethylsilyl-, germyl-, -stannyl- and the bromoethyl-substituted stannacyclohexadienes III, IV, V and VI are obtained. The bis(trimethylsilyl- and -germyl) substituted stannacyclohexadienes VIII and X have been synthesized starting from III and IV, respectively. Arsabenzene (XII) is formed in good yields by treating arsenic trichloride with III, IV and V. 4-Trimethylsilyl-1-arsabenzene (XIII), 4-trimethylgermyl1-arsabenzene (XIV) and 4-(2-chloroethyl)-1-arsabenzene (XV) can be prepared by treating VIII, X and VI respectively with arsenic trichloride, ¹H NMR, IR, UV and mass spectral data of the new compounds are described.     

Thermal and photochemical oxidation of 2,6-dimethylphenyl phenyl ether: A model for poly(2,6-dimethyl-1,4-phenylene oxide)

The oxygenation of 2,6-dimethylphenyl phenyl ether (I) at 260°C has resulted in the formation of 4-methylxanthone (II), 2-hydroxy-3-methylbenzophenone(III), 2-phenoxy-3-methylbenzaldehyde (IV), 2-phenoxy-3-methylbenzoic acid (V), 2-phenoxy-3-methylbenzyl o-cresotinate (VI), 2-phenoxy-3-methylbenzyl alcohol (VII), and 2-phenoxy-3-methylbenzyl 2-phenoxy-3-methylbenzoate (VIII), The photochemical oxidation at 75° produced compounds II, III, IV, VII, and VIII. Oxidation of poly(2,6-dimethyl 1,4-phenylene oxide) film at 200°C and photochemically at 50°C produced a carbonyl band at ca. 1730 cm^?1. The gel content of the photochemically aged film could be significantly reduced and the 1730 cm^?1 peak in the thermally aged specimen could be moved to longer wavelength by base treatment. The isolation of compound VIII in both processes with the model compound and the results with the polymer allows us to propose an ester group as a crosslinking unit in thermally and photochemically aged polymer film.     

Acyclische isomere von aminofluorsilanen,intramolekulare cyclisierung

Fluorosilanes react with lithiated amines to yield aminofluorosilanes. Iso- and sec-butylaminofluorosilanes with bulky ligands form the isomers (I–VII). The cyclisation of monoorganofluorosilanes depends on the size of the substituents. IV and V dimerise by HF-elimination (VIII, IX) and VII cyclises by migration of a methanide ion (X). The mass, ¹H, ¹⁹F and ²⁹Si NMR spectra of the compounds are reported.     

Synthese und Struktur von 1.4-Diborylcyclopentadienen

Bis(trimethylsilyl)cyclopentadiene reacts with two equivalents of boron halides to the bis(dihalogenoboryl)cyclopentadienes I, II and III. Reactions of I, II and III with tetramethyltin and dimethylamine yield the dimethyl- and bis(dimethylamino)-substituted compounds IV and V. The fluoro compound VI is synthesized by the reaction of III with arsenic trifluoride. Addition of pyridine to I and II yields the adducts VII and VIII. Structure and bonding properties of I–VIII are discussed by ¹H-, ¹³C-, ¹¹B- and ¹⁹F.n.m.r- and by i.r. and m.s. data.     

SYNTHESIS AND ANTIMICROBIAL SCREENING OF SOME NEW 4-IMINO-3,5,7-TRISUBSTITUTED PYRIDO[2,3-d]PYRIMIDINES AND THEIR RIBOFURANOSIDES AS POTENTIAL CHEMOTHERAPEUTIC AGENTS

Some new nucleosides, viz. 4-imino-3,5,7-trisubstituted-1-(2′,3′,5′-tri-O-kbenzyl–β-D-ribofuranosyl)pyrido[2,3-d]pyrimidin/e–2(1H)-ones/ thiones(VII/VIII), have been synthesized by condensation of trimethylsilyl derivatives of 4-imino-3,5,7-trisubstituted pyrido[2,3-d]pyrimidin/e-2(1H)-ones/thiones (III/IV) with β-D-ribofuranosyl1-acetate-2,3,5-tribenzoate. Compounds III/IV have been synthesized by refluxing 2-amino-3-cyano-4,6-disubstituted pyridine (II) with substituted an arylisocyanate or an isothiocyanate respectively. The structure of all the synthesized compounds have been established by IR and ¹H NMR studies. These compounds have been screened for antimicrobial activities in order evaluate. The possibility of the derivatives to be used as potential chemotherapeutic agents.     

Synthese und reaktionen von zinn-substituierten pentadienderivaten

(1E, 4E)-1,5-Bis(trimethylstannyl)pentadiene-1,4 (III), 1E-1-trimethylstannyl-pent-1-ene-4-yne (IV) and the 1,1-dialkyl-1-stannacyclohexadienes-2,5 VII and VIII have been synthesized by hydrostannation of pentadiyne-1,4. (1E, 4E)1,5-Dibromapentadiene-1,3 (IX) is formed from III and 1,1,2,4,5,5-hexabromopentane (X) from IX by reaction with bromine. Butyllithium reacts with III to give (1E, 4E)-1,5-dilithium pentadiene-1,4 (XI). The reactions of butyl- and methyllithium with VII and VIII give only the monolithium compounds XIII, XV and XVII. All lithium compounds are characterised in the form of their trimethylsilyl derivatives XII, XIV, XVI and XVIII. ¹H NMR, IR, UV and mass spectral data are described.     

Heterocycles. Part V. Reaction of α,β-unsaturated carbonyl compounds with arylacetamides. A synthesis of 2-pyridone derivatives

The reaction of 1,3-diaryl-2-propene-1-ones I with arylacetamides II, in the presence of sodium ethoxide under reflux, for two hours, gave the corresponding 3,4,6-triaryl-3,4-dihydro-2(1H)-pyridones IV. However, when the reaction of these ketones was carried out in the presence of sodium hydride, they gave the corresponding 3,4,6-triaryl-2(1H)-pyridones VI or a mixture of IV and VI. When 1,3-diaryl-2-propyne-1-ones V were reacted with arylacetamides, in the presence of sodium hydride, they yielded the corresponding 2-pyridones VI. Treatment of compounds IV with selenium produced the corresponding 2-pyridones VI. Acetylation of the latter compounds gave the corresponding 2-acetyl derivatives VIII. The structure of all products was confirmed by chemical and spectroscopic evidence, and the mechanism of the reactions was discussed.     

Oxidation number: issues of its determination and range

The paper is aimed at the issues of oxidation state determination and limiting values. The possibility of existence of compounds containing an atom with the oxidation number beyond the current common values, i.e., below −IV and above +VIII are discussed. Three principal modes of preparation of compounds with the oxidation number exceeding VIII, electrochemical anodic oxidation, photoionization, and nuclear β-decay, are evaluated. Failure to prepare compounds containing an atom with the oxidation number below −IV is rationalized. The paper provides an opinion on uncertainties in oxidation state determination in three kinds of compounds: binary compounds, nitrosyl complexes, and compounds containing mutually bonded atoms of the same element. The questions are discussed from the viewpoint of correlation of “man-made” quantities and objective, experimentally obtainable data.     

Electrooxidation of alken-1-ylarenes in aqueous alcohol solutions

In the initial stages of the electrooxidation of alken-1-ylarenes-propenyl-benzene (Ia) and 4-propenylanisole (Ib)- in aqueous alcohol solutions, 1,2-dialkoxypropyl- (II), 1-hydroxy-2-alkoxypropyl- (VII), and 1,2-dihydroxy-propyl arenes (VIII) are formed. Subsequent rupture of the C-C benzyl bond converts the ethers (II) into benzaldehyde acetals (III) and benzaldehydes (IV), and compounds (VII) and (VIII) into (IV). Benzaldehydes (IV) are also formed from (II) by hydrolysis of the acetals (III)- partly for (IIIa) and completely for (IIIb). Electrolysis of (Ia and Ib) in aqueous alcohol solution leads mainly to their conversion into benzaldehydes (IV).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2356–2361, October, 1991.     

Effect of six triorganotin(IV) compounds on nitrification and ammonification in soil

The effects of six triorganotin(IV) compounds and of Thiram on nitrification and ammonification in soil were investigated. Low concentrations of up to 50 μg g^?1 of the triorganotin(IV) compounds enhanced nitrate-nitrogen (NO₃^?-N) production in soil. Except for diphenylbutyltin bromide, which inhibited nitrification at 250 μg g^?1, the other triorganotin(IV) compounds were inhibitory at concentrations of 100 μg g^?1 to less than 250 μg g^?1. At 10 μg g^?1, only triphenyltin acetate was less inhibitory towards nitrification compared with Thiram. At 250 μg g^?1, Thiram exerted a strongly persistent inhibitory effect towards nitrification. The NO₃^?-N level recorded 28 days after application was only 0.10 μg g^?1 soil. With the triorganotin compounds NO₃^?-N levels of 7.05–12.06 μg g^?1 soil were recorded 28 days following their application. The deleterious effects of the triorganotin(IV) compounds were less persistent and recovery of nitrification was evident seven days after application. Low concentrations of Thiram and triorganotin(IV) compounds inhibited ammonification, whereas higher concentrations enhanced ammonification. Complete inhibition of ammonification was attained 21–28 days after application of Thiram at 50 μg g^?1. On the other hand, with the triorganotin(IV) compounds, except for diphenylbutyltin bromide at 10–50 μg g^?1, ammonification persisted at all concentrations 28 days after application.     

Indenyl and fluorenyl transition metal complexes.: IV. Reactions of 2- and 4-azafluorenes with chromium hexacarbonyl

Reactions of 2- and 4-azafluorenes (I, II) and their methyl derivatives, 3-methyl-2-azafluorene (III) and 7-methyl-4-azafluorene (IV) with chromium hexacarbonyl in a $\text{1}\text{1}$ diglyme/heptane mixture at 140°C have been studied. A N-donor complex, C₁₂H₉NCr(CO)₅ is formed in the reaction of I with Cr(CO)₆. Compounds II–IV react to give arenechromiumtricarbonyl derivatives with benzene rather than pyridine ring bound to the metal. [η⁶-(4b,5,6,7,8,9b)-4-Azafluorene]chromiumtricarbonyl (VIII) gives the corresponding hydrochloride under the action of HCl. Methyl iodide decomposes VIII to produce 4-azafluorene iodomethylate. Deprotonation of VIII with BuLi in ether at ?20°C followed by dilution with hexane leads to precipitation of the corresponding Li salt (Xb), having η⁶-structure. Methylation of Xb with methyl iodide proceeds stereospecifically to yield the exo-methyl derivative XII. Treatment of VIII with excess t-BuOK at 25°C in THF results in a mixture of η⁶-(Xa) and η⁵-anions (XI), the former predominating.     

Mass spectrometric study of isatins II. N-propyl(allyl,propargyl)isatins

The mass spectra of N-propyl- (I), N-allyl- (IV), and N-propargylisatin (VII) and their 5-methyl (II, V, VIII) and 7-methyl (III, VI, and IX) derivatives were recorded. It is shown that a portion of the [M-2CO]⁺ ions in the mass spectra of N-propargylisatins undergo rearrangement to give ions with a quinoline structure. A scheme for the fragmentation of the investigated compounds is presented. The mass spectra of the 5- and 7-methyl derivatives are compared.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 639–641, May, 1977.     

Reactivities of osmium(VIII), iridium(IV) and platinum(IV) towards glycolaldehyde

Oxidations of glycolaldehyde (GA) to glyoxal by osmium(VIII), iridium(IV) and platinum(IV) have been investigated in aqueous solution, and the orders with respect to each [reactant] determined. The reaction involving iridium(IV) takes place through intermediate formation of free radicals in a MeCO₂Na-MeCO₂H buffer medium, whereas a one-step two-electron transfer process occurs in the oxidations by Os^VIII and Pt^IV in an alkaline medium. Mechanisms consistent with the experimental findings are proposed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Intramolecular sulphonyl-amidomethylation. Part I. Cyclization of benzylsulphonamides

Cyclization of benzylsulphonamides with aldehydes in strong acid media is a synthetically useful route to 3,4-dihydro-1H-2,3-benzothiazine 2,2-dioxides III. With insufficient acid strength or reaction time, kinetic products IV and VI are obtained; the latter compounds can be converted into the thermodynamic products III under stronger conditions. The reactions proceed via imine VII or iminium VIII compounds as common intermediates.     

5-Aza(Oxa,Thia)-2,8-dithia-1-stanna(II)-bicyclo[3.3.01,5]octane Intramolekular basenstabilisierte Stannylene

5-Aza(oxa, thia)-2, 8-dithia-1-stanna(II)-bicyclo[3.3.0^1,5]octanes — Intramolecular Stabilized Stannylenes By the reaction of tin(II) butoxide with mercaptanes of the general type E(CH₂? CH₂SH)₂ (E ? N-t-Bu, NMe, O, S) at temperatures up to 50°C the 5-aza(oxa, thia)-2, 8-dithia-1-stanna(II)-bicyclo[3.3.0^1,5]octanes I—IV are obtained in high yields. The compounds are monomeric in solution. Contrary at higher reaction temperatures (80°C) the spiro-compounds of the type [E(CH₂CH₂S)₂]₂Sn ( V—VIII ) are formed. Some typical stannylene reactions of I—IV with BF₃, Cr(CO)₆, Br₂, and PhS? SPh show the high reactivity of the compounds. Their structure is investigated by ¹H, ¹³C, and ¹¹⁹Sn n.m.r., i.r., and Mössbauer spectroscopy.     

Liquid-liquid extraction and spectrophotometric determination of palladium with 2-mercaptobenz-amide

2-Mercaptobenzamide (MBA) was investigated as a reagent for the extraction of palladium. The palladium complex of MBA was extracted into tributyl phosphate (TBP). The pK_a of the ligand was 5.45 with the stability constant of the palladium complex β₂=10^7.1. The composition of the complex in TBP was Pd:MBA:TBP=1:2:2. Addition of sodium chloride accelerated the rate of extraction. Various interfering ions could be masked with EDTA; Ag(I), Au(III), Os(VIII), Se(IV), Te(IV) etc. interfered. The molar absorptivity was 1.59×10⁴ l mol^?1 cm^?1; 1–35 μg Pd could be determined at pH 6.0.     

Studies on the Constituents of the Root-Bark of Hernandia Ovigera L. (III)

In the course of continuing search for the constituents of the root-bark of Hemandiu ovigera L., led to the isolation of eight compounds: desoxypodophyllotoxin(I), thalicarpine(III)) dehydrothalicarpine(IV), ovigerine(V), hernangerine(VI), hernandonine(VIII) and two unknown substances, mp. 219–220° and mp. 269–270°. Desoxypodophyllotoxin( I) and thalicarpine(III) exhibited a distinctively cytotoxic activity against nasopharynx carcinoma was reported by S. M. Kupchan et.al^3,9. Dehydrothalicarpine( IV) is merely a dehydro product of thalicarpine(III) at C–6a and C–7 of aporphine moiety. The isolation of dehydrothalicarpine(IV) made the first instance from Hernandia ovigera L. Comparison of their components distribution in each part of Hernandia ovigera was shown in Table I.     

Diorganophosphinoalkyl-dimethylzinnchloride: Synthese,struktur und reaktionsverhalten

Phosphinoalkylchlorostannanes of the type Me₂Sn(Cl)(CH₂)_nPR¹R² (n = 2,3) (I–VIII) are synthesized by a redistribution reaction of the tetraorganostannanes Me₃Sn(CH₂)_nPR¹R² (n = 2,3) with trimethyltin chloride. In non-coordinating solvents the tin atom in I–IV is tetracoordinated, whereas NMR data indicate an intramolecular SnP interaction for V–VIII. In the solid state compound III exists as an 1:1 adduct with trimethyltin chloride. With methyl iodide compounds I–VIII form the phosphonium stannates Me₂SnCl) (I) (CH₂)_nP+R¹R²Me (XI–XIII). Compounds I–VIII are suitable starting materials for the synthesis of the tin hydrides Me₂Sn(H)(CH₂)_nPR¹R² (XIV–XVI) and the distannanes [Me₂Sn(CH₂)_nPR¹R²]₂ (XVII–XIX). The reaction of I–VIII with sodium in liquid ammonia or with lithium in THF, respectively, yields solutions of the corresponding alkali stannides Me₂Sn(M)(CH₂)_nPR¹R² (M = Li, Na).     

Coordination behavior of the carboxylate group in organotin(IV) derivatives of 2-[(2′,4′,6′-tribromophenylamido)]benzoic acid and 3-[(2′,4′,6′-tribromophenylamido)]propenoic acid: Spectroscopic studies

The complexes of two organic carboxylates (containing {O,O}-donor atoms) with Me₂Sn^(IV)Cl₂, n-Bu₂Sn^(IV)Cl₂, Bz₂Sn^(IV)Cl₂, Oct₂Sn^(IV)O, Me₃Sn^(IV)Cl, n-Bu₃Sn^(IV)Cl, Ph₃Sn^(IV)Cl, Ph₃Sn^(IV)Cl, and Bz₃Sn^(IV)Cl having ligand-to-metal ratios of 1: 2 and 1: 1 were prepared by two different methods. The FT-IR spectra clearly demonstrated that organotin(IV) moieties react with {O,O}-atoms of the ligands. It was found that in all cases the COO⁻ group was acting as bidentate in the solid state. The ¹¹⁹Sn NMR data revealed that the organotin(IV) moiety has a tetrahedral geometry in non-coordinating solvents. The biological activity of these compounds was compared with that of their precursors, and all the synthesized compounds show significant antibacterial activity. The antifungal activity of the complexes against six plant pathogens has been estimated. The complexes display marked toxicity against these fungi and are more fungitoxic than free acids. The compounds have also shown significant cytotoxicity against Brine Shrimp (Artemia salina). The article was submitted by the authors in English.     

Infrared matrix isolation studies on tautomerism of cytosine and isocytosine methyl-derivatives

IR N₂ matrix isolation spectra have been recorded in the OH, NH and CO stretching region. The spectra were interpreted to determine the structure of investigated compounds: 1-methylcytosine predominates in the aminooxo form I; 3-methylcytosine and 1-methylisocytosine - iminooxo III and IV; 6-methylisocytosine and N(2)-monomethylaminoisocytosine - aminohydroxy forms VII and VIII.