Phytoecdysones ofAjuga turkestanica VI. 22-Acetylcyasterone

Summary The leaves ofAjuga turkestanica (Rg1.) Briq. have yielded a new ecdysone — 22-acetyl-cyasterone. The mass spectrum of this new ecdysone and the features of it due to the presence of the acetoxy group at C-22 have been discussed.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 215–219, March–April, 1978.     

Cembrenolides of a soft coral Lobophytum sp. (coelenterata, octocorallia, alcyonacea)

The known cembrenolide sarcophin and its new acetoxy derivative — 13-acetoxy-7,8-epoxycembra-1(15),3,11-trien-2,16-olide — have been isolated from the soft coralLobophytum sp.. The compounds isolated are inhibitors of the activity of Na⁺K⁺-ATPase and are membranotropic agents. The structures of the compounds have been shown on the basis of the results of NMR spectroscopy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 762–765, November–December, 1990.     

Chemistry of indole

5-Methoxy-3-carbethoxyindoles are nitrated primarily in the 4 position. Replacement of the methoxy group by an acetoxy group leads to a change in orientation — only the 6 isomer is obtained. In the case of the similarly constructed 5-hydroxyindoles, monosubstitution cannot be accomplished under various conditions, and only the 4,6-dinitro derivative is formed. The synthesis of the corresponding amines by reduction of the nitro compounds is described.See [1] for communication XXXVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1646–1653, December, 1973.     

Bromination and nitration of 2 (3) - ph enyl-5(6)-hydroxybenzofurans

It was established that substituents primarily are incorporated in the benzene ring in the bromination and nitration of 2(3)-phenyl-5(6)-hydroxybenzofurans. The acetoxy derivatives of the same benzofurans are brominated and nitrated only in the free position of the furan ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 311–315, March, 1976.     

Bisindoles. 15. Acidic condensation of bis(2-ethoxycarbonyl-5-indolyl) oxide and bis(2-ethoxycarbonyl-5-indolyl)methane with aromatic aldehydes

The acidic condensation of bis (2-ethoxycarbonyl-5-indolyl) oxide and bis(2-ethoxycarbonyl-5-indolyl)methane with aromatic aldehydes was studied. Bis(3-chloro) compounds with labile chlorine atoms, by nucleophilic substitution of which the corresponding dimethylamino, hydroxy, methoxy, acetoxy, cyano, and mercapto derivatives were obtained, were isolated.See [1] for communication 14.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 365–368, March, 1983.     

An Improved Method for the Preparation of Tetra-Coordinate Platinum(II) Chloro-Complexes Containing Bidentate or Terdentate Ligands Starting from cis/trans-[PtCl2(SMe2)2]

An improved method for the preparation of differently charged chelate Pt(II) chloro-complexes is reported. All the complexes have been obtained rapidly and in high yield, by simply reacting equimolar amounts of cis/trans- dichlorobis(dimethylsulphide)platinum(II) with the chelate ligand in an appropriate solvent (CH₂Cl₂, MeOH or H₂O). The ligands chosen were: 1,2-bis(diphenylphosphino)ethane (P—P), pyridine–2-carboxylate (N—O⁻), 2-[(methylthio)methyl]pyridine (N—S), 1,10-phenanthroline (N—N), bis(2-pyridylmethyl)sulphide (N—S—N), di-(2-picolyl)amine (N—N—N), pyridine-2,6-dicarboxylate (O—N—O²⁻) and 2,6-bis(methylthiomethyl)pyridine (S—N—S).     

On the Existence and Hydrolytic Stability of Titanosiloxane Bonds in the System: Glycidoxypropyltrimethoxysilane-Water-Titaniumtetraethoxide

Heterometal materials based on glycidoxypropyltrialkoxysilane and titaniumalkoxide are used for optical applications and require a high homogeneity on the molecular level. The presence of heterometal titanosiloxanes, their distribution and hydrolytic stability should influence the homogeneity of these materials. 29Si and 17O NMR spectroscopy has been used to investigate sols with molar ratios Si : Ti = 1 and H2O : OR (H) = 0.5 – 2.0 and their gels after heat treatment at 130°C. The presence of Si—O—Ti bonds in sols with a low water content (H < 0.2) and in the corresponding gels was identified by the high-field shift of the 29Si NMR signals of T1 and T2 units of up to 2–3 ppm compared to corresponding signals of homo-condensed Si—O—Si bonds. The existence of Si—O—Ti bonds in the sols is supported by 17O NMR spectra which show a characteristic signal around 340 ppm. A cleavage of the Si—O—Ti bonds occurs with increasing water/OR ratio in the sols. The cleavage of the heterometal bonds and the building up of homo-condensed species leads to a separation into areas with predominantly Ti—O—Ti and Si—O—Si bonds resulting in a decreased molecular homogeneity of the materials.     

多乙酰氧基硅烷与环氧氯丙烷的开环反应

本文详细地研究了在5-叔丁基呋喃甲酸铬的存在下,多乙酰氧基硅烷与环氧氯丙烷的开环反应及其产物。     

3-Nitro-5-chloromethylsalicylaldehyde in the synthesis of photochromic spirochromenes of the indoline series

The nitration of 5-chloromethylsalicylaldehyde leads to 3-nitro-5-chloromethylsalicylaldehyde, the chlorine atom in which is smoothly replaced by a hydroxy or acetoxy group. The salicylaldehydes obtained condense with 1,3,3-trimethyl-2-methylene-indoline to give the corresponding photochromic indolinespirochromenes. The spectral-kinetics of the photochromic transformations of the spirochromenes are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 196–199, February, 1978.     

Photochemistry of 5-aryl-2(3H)-furanones. : A new route to the synthesis of chromones

The photochemistry of 5-phenyl-, 5-(2',5'-dimethoxyphenyl)-, 5-(2'-acetoxy-5'-methoxyphenyl)- and 5- (2',5'-diacetoxyphenyl)- 2(3H)-furanone (1a-d) has been investigated. Compound 1a yields phenyl vinyl ketone as expected. Similarly, 1b affords the corresponding aryl vinyl ketone but, in this case, photodimerization also occurs. Irradiation of the two o-acetoxyaryl furanones 1c and 1d gives rise to the formation of chromones as the main products. This interesting result can be accounted for in terms of a photochemical opening of the lactonic ring followed by radical addition to the acetoxy group.     

Development of a New Alkali Resistant Coating

The effect of different new sol-gel BaO—TiO₂—SiO₂ and CaO—BaO—TiO₂—SiO₂ coatings on long-term durability of glass fiber reinforced cement (GRC) was examined. Flexural strength of GRC was measured after curing for 7 to 150 days. Significant improvement was observed for coated GRC in this study and discussed in terms of the hydrate formation at interface. Concerned with the alkali resistance, CaO—BaO—TiO₂—SiO₂ coating was more effective than BaO—TiO₂—SiO₂ coating. In special, the 10CaO—10BaO—60TiO₂—20SiO₂ coating, prepared by sol-gel method, was recommended for the highest flexural strength of GRC and least corrosion at surface of E-glass fiber.     

A New Predictive Equation for the Depression in Freezing Points of Multicomponent Aqueous Solutions Conforming to the Linear Isopiestic Relation

The linear isopiestic relation has been used together with a well-known thermodynamic equation to establish a new predictive equation for freezing point depression. This equation can provide predictions for multicomponent solutions conforming to the linear isopiestic relation using only information on the corresponding binary subsystems. The predictive capability of the equation has been tested by comparing with the experimental data at 25°C reported in the literature and particularly those of Pathwardhan and Kumar. The systems used are NaCl—MgCl₂—H₂O, NaCl—BaCl₂—H₂O, NaCl—CaCl₂—H₂O, LiCl—NaCl—H₂O, LiCl—KCl—H₂O, LiCl—CsCl—H₂O, NaCl—KCl—H₂O, and NaBr—KBr—H₂O. The predictions of the two equations agree well with the experimental data although our new equation is, in general, better.     

The chemistry of pyridinethiols and related ligands,Part 9. Synthesis,spectroscopy and crystal structure of sulphur bridged dimeric [{η3-(O-μ-S)-1-oxopyridine-2-thione}(triphenylphosp hine)silver(I)]

Reaction of 1-hydroxypyridine-2-thione (HpyOS) in CHCl3 with Ag2CO3 suspended in CHCl3 under magnetic stirring followed by addition of PPh3 yields a product of stoichiometry: Ag(pyOS)(PPh3). The compound adopts a dimeric structure [Ag(pyOS)(PPh3)]2 (1) where each Ag atom acquires a distorted tetrahedral geometry by co-ordinating to one oxygen, two sulphur and one phosphorus atoms. The Ag2S2 core forms a parallelogram [Ag—S 2.507(1), 2.822(1)Å] with Ag—S—Ag and S—Ag—S angles of 74.8(1) and 105.2(1)°, respectively.     

Isolierung und Strukturaufklärung eines hämolytisch wirkenden Polypeptides aus dem Abwehrsekret europäischer Unken

Zusammenfassung Ein aus 24 Aminosäuren bestehendes Polypeptid wurde aus dem Abwehrsekret europäischer Unken isoliert. Abbauversuche machen folgende Primärstruktur wahrscheinlich:H₂N—Gly—Ile—Gly—Ala—Leu—Ser—Ala—Lys—Gly—Ala—Leu—Lys—Gly—Leu—Ala—Lys—Gly—Leu—Ala—GluX—His—Phe—Ala—Asp(NH₂)₂.Das Polypeptid (Bombinin) wird durch die proteolytischen Enzyme des Unkengiftes rasch abgebaut. Es wirkt hämolytisch und zeigt gewisse strukturelle Analogien zu Melittin.

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Isolation and structure of an hemolytic polypeptide from the defensive secretion of european bombina species

A tetracosapeptide has been isolated from the defensive secretion of European unks. The following primary structure is proposed:H₂N—Gly—Ile—Gly—Ala—Leu—Ser—Ala—Lys—Gly—Ala—Leu—Lys—Gly—Leu—Ala—Lys—Gly—Leu—Ala—GluX—His—Phe—Ala—Asp(NH₂)₂.The polypeptide (bombinin) is quickly hydrolyzed by the proteolytic enzymes of the unk toxin. Bombinin shows hemolytic activity. Its structure resembles somewhat that of melittin.

     

A new synthetic route to aminothiazolinones

Novel 2-(5-R-1,3,4-thiadiazol-2-yl)aminothiazolin-4-ones 6a—h and 2-imino-3-(5-R-1,3,4-thiadiazol-2-yl)thiazolidin-4-ones 7a—h were prepared by treating N-(5-R-1,3,4-thiadiazol-2-yl)thioureas 4a—h with chloroacetic acid on various solid supports under microwave irradiation. Tautomeric mixtures of compounds 6a—h and 7a—h were obtained in all cases. In alkaline and neutral media, compounds 6a—h were the major products, while in acid media, 7a—h were the major products.     

Influence of Proton Transfer on the Formation of Hydrogen-Bonded Complexes of Higher Stoichiometry and on their Dissociation into Free Ions

Proton transfer in a given H-bond A—H—B—(H)A_–— H⁺—B—(H) considerably enhances the strength of the electron donor sites of the first partner and that of proton donor sites possibly present in the second one. This leads to the formation of complexes of higher stoichiometry of the type B— H⁺—(A^–—H—A--H—A--H--)or A^–---(H—B⁺—H----B—H—B—H----) where the self-association bonds are much strengthened. This is due to the high stability of the homoconjugated anions or cations in the corresponding ion pairs. In polar solvents like acetonitrile, the ion pairs may dissociate into free ions. The variety of the entities that can be formed necessitates a diversification of the quantitative concepts connected with the proton transfer process. Besides the average value x₁ of the fractions of the various complexes in the ionized form, other quantities are defined that can also be used in the case of partial dissociation: (1) the percentage of ionized base molecules and (2) the fraction of donor molecules AH ionized after direct interaction with B. A further characteristic used in this generalized treatment is the average number n of proton donor molecules perturbed by one base molecule. Examples of determinations of these various parameters from calorimetric, infrared, or NMR data from the literature are presented and new quantitative correlations established.     

Structural Studies on Saturated Aqueous Solutions of Manganese(II), Cobalt(II), and Nickel(II) Chlorides by X-ray Diffraction

As a part of our studies on crystallization processes of electrolytes, the structure of aqueous solutions of MCl₂ (M = Mn, Co, Ni) equilibrated with hydrate crystals, MCl₂ · mH₂O (m = 6, 4, 2), was investigated by means of X-ray diffraction at 25, 40, 55, and 70°C. The complexes formed in MnCl₂ solutions, were found to be mixed–ligand chloroaqua octahedral complexes of M²⁺ ions with the Mn—O and Mn—Cl distances of about 220 and 251 pm, respectively. The average number of Mn—Cl and Mn—O interactions increased from 1.2 to 1.9 and decreased from 4.8 to 4.1, respectively, with changing MnCl₂ solutions from Mn25 (MnCl₂ solution at 25°C) to Mn70 (MnCl₂ solution at 70°C). In the octahedral species of Co²⁺, the Co—O and Co—Cl distances were found to be about 211 and 240 pm, respectively. With an increase in the saturated concentration by changing temperature from 25 to 70°C, the average coordination number of the Co—Cl contact per Co²⁺ increased from 0.5 to 1.2, and the average number of Co—O interactions decreased from 5.5 to 4.8. The structural analysis was carried out by taking into consideration the existence of the tetrahedral species in the solutions saturated at 40, 55, and 70°C, on the assumption of the existence of [CoCl₄]^2–. The Co—Cl distance was found to be 228 pm, while the number of Co—Cl interactions in the [CoCl₄] complex was calculated to be 3.7 by the least-squares calculations. The Ni—O and Ni—Cl distances were estimated to be about 206 and 237 pm, respectively. The frequency factor n of the Ni—O and Ni—Cl interactions decreased monotonously from 5.6 to 5.0 and increased from 0.4 to 1.0, respectively, with increasing NiCl₂ concentration. The n values of the Co—Cl and Ni—Cl interactions of the octahedral complexes increased sharply with concentration at higher concentrations. Comparing structures of the complexes in the saturated solutions and the hydrate crystals of these metal ions, we discussed a role of the complexing species on crystallization of the hydrates.     

Indole derivatives. 135. 5-[2-(4-Methoxyphenyl)ethenyl]indolines and indoles

5-[2-(4-Methoxyphenyl)ethenyl]indolines were obtained from 5-formyl-1-methyl- or 5-forrayl-1-benzylindolines by the Witting reaction with 4-methoxybenzylidenetriphenylphosphorane. Their dehydrogenation led to the formation of the corresponding compounds of the indole series. The corresponding hydroxy compounds were obtained by demethylation of the methoxyindole with boron tribromide and were converted into the acetoxy derivatives of indoline and indole.For communication 134, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 911–914, July, 1989.     

Ortho effect in the fragmentation of 2-acetoxychalcones under electron impact

2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions. The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond. The intense flavylium ion originates—as shown by specific labelling with ¹⁸O—from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar? O bond and (b) sequential elimination of ketene and a hydroxy radical.