Synthesis of amide derivatives of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript>

A number of secondary and tertiary chlorin e ₆-13-amides were synthesized in high yield by the action of primary and secondary amines on methylpheophorbide a under mild conditions. Unlike the secondary amides, tertiary 13-amides were shown to exist as two stereoisomers differing by orientation of the amide group plane with respect to the macroring. The reaction of methylpheophorbide a with 2-aminoethanol gave chlorin e ₆ derivatives containing one, two, and three hydroxy groups.     

Amidation of the ester group of methylpheoforbide <Emphasis Type="Italic">a</Emphasis> with sterically nonhindered primary and secondary aliphatic amines

It is shown that the reaction of methylpheoforbide a with a series of primary and secondary aliphatic amines at elevated temperature (boiling in toluene) leads to the amidation of carbomethoxy group in the position 13(2) of the methylpheoforbide a exocycle instead of the cleavage of exocycle with the formation of the corresponding 13-amides of the chlorin e ₆. Possible reasons of the observed change in the reaction pathway are presented.     

Synthesis of novel dibenzo-2,6,9-triazabicyclo[3.3.1]nonanes from <Emphasis Type="Italic">o</Emphasis>-tosylamino- and <Emphasis Type="Italic">o</Emphasis>-mesylaminobenzaldehydes

Condensation of o-tosylaminobenzaldehyde with γ-aminobutyric, 4-aminophenylthioacetic, and p-aminobenzoic acids and β-alanine gave 6,12-epimino-5,11-ditosyl-5,6,11,12-tetrahydrodibenzo[b, f]-1,5-diazocines with carboxyl-containing substituents at the bridging N atoms. The structures of three products were examined by X-ray diffraction analysis. Condensation of o-mesylaminobenzaldehyde (prepared by the McFadyen-Stevens reaction) with NH₄OAc and primary amines afforded 6,12-epimino-5,11-dimesyl-5,6,11,12-tetrahydrodibenzo[b, f]-1,5-diazocine derivatives.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2165–2171, October, 2004.     

Functionalization of sterically hindered <Emphasis Type="Italic">o</Emphasis>-benzoquinones: amino-substituted 3,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-<Emphasis Type="Italic">o</Emphasis>-benzoquinones

New sterically hindered functionalized o-quinones were synthesized by the 1,4-nucleophilic addition of secondary cyclic amines to 3,6-di(tert-butyl)-o-benzoquinone. The ability of these o-quinones to form o-semiquinone complexes with transition and main-group metals was studied by ESR spectroscopy in solution. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1786–1793, September, 2007.     

Synthesis of benzo[<Emphasis Type="Italic">g</Emphasis>]quinoline-5,10-diones

Addition of HCl to 2-amino-3-(4-methyl-3-oxopentynyl)-1,4-naphthoquinone in CHCl₃ at 20 °C is followed by its cyclization to 4-chloro-2-isopropylbenzo[g]quinoline-5,10-dione. Chlorine atom in this compound can be easily replaced by dialkylamino group upon treatment with secondary amines. 4-Dialkylamino-2-isopropylbenzo[g]quinoline-5,10-dione is also formed by the direct reaction of the starting ketone with secondary amines. Syntheses of 2-amino-3-(4-methyl-3-oxopentynyl)-1,4-naphthoquinone from 2-bromo-and 2-amino-3-iodo-1,4-naphthoquinones are also described. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2381–2385, December, 2007.     

Charge-charge and cation-<Emphasis Type="Italic">π</Emphasis> interactions in ligand binding to G protein-coupled receptors

To study the importance of charge–charge and cation-π interactions for the binding of positively charged amine ligands to their receptors, the energies of interaction between [(CH₃)₄–N]⁺, [(CH₃)₃–NH]⁺, and [(CH₃)₄–NH₃]⁺ and acetate, as a model of Asp and Glu, and with benzene, as a model of aromatic side chains, were obtained at the MP2/aug-cc-pVDZ level of theory. The free energies of solvation in water were also calculated for the different amines. It was found that, although primary amines form stronger charge–charge interactions with acetate than tertiary or quaternary amines, the difference is not large enough to compensate their higher solvation energy. Quaternary amines show the weakest interaction with acetate. However, their alkyl groups can interact with various aromatic groups, enhancing ligand binding to the receptor. The analysis was completed with MD calculations on amine binding to the G protein-coupled receptors β₂AR and CCR5. The calculations on the model systems were found to be in good agreement with the simulations of the ligand-receptor complexes. Contribution to the Serafin Fraga Memorial Issue.     

Reactivity of <Emphasis Type="Italic">N</Emphasis>-(chlorodimethylgermyl)methyl and <Emphasis Type="Italic">N</Emphasis>-(chlorodimethylsilyl)methyl derivatives of lactams and amides toward Grignard reagents

N-[(Chlorodimethylgermyl)methyl]lactams and -amides containing a five-coordinate germanium atom react with Grignard reagents chemoselectively by the Ge-Cl bond to form four-coordinate germanium compounds. The method of competitive reactions was used to establish that respective five-coordinate germanium and silicon compounds are almost equally reactive toward Grignard reagents but much more reactive than model four-coordinate germanium and silicon compounds.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1462–1465.Original Russian Text Copyright © 2004 by Bylikin, Shipov, Kramarova, Artamkina, Negrebetskii, Baukov.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis of aryloxyacetaldehydes and <Emphasis Type="Italic">N</Emphasis>-(aryloxyethyl)cyclohexanamine hydrochloroides

Oxidation of 2-(aryloxymethyl)oxiranes with periodic acid gave a series of aryloxyacetaldehydes which reacted with cyclohexylamine in THF, and subsequent reduction of Schiff bases thus obtained with sodium tetrahydridoborate resulted in the formation of the corresponding secondary amines which were isolated and characterized as hydrochlorides.     

Selective hydrogenation of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated carbonyl compounds on supported Ru-Sn catalysts

Selective catalytic hydrogenation of unsaturated carbonylic compounds to unsaturated alcohols on bi-metallic Ru-Sn catalysts/support was studied. The catalysts were prepared by the sol–gel method and the method of co-impregnation with the objective to evaluate selected parameters of preparation, i.e., the amount of modifying tin and the support (TiO₂, SiO₂, Al₂O₃), on their catalytic activity and selectivity. A significant modifying effect of tin was proved, especially its positive effect on the selectivity. Concerning the selectivity as well as the activity, Al₂O₃ was found to be the optimal support. Furthermore, the effect of a substrate was studied with results proving suitability of this catalytic system for hydrogenation of unsaturated aldehydes; however, the utilization for selective hydrogenation of unsaturated ketones was found inadequate.     

Syntheses proceeding from <Emphasis Type="Italic">N</Emphasis>-(oxiran-2-ylmethyl)-<Emphasis Type="Italic">N</Emphasis>-ethylaniline

The preparation of N-(oxiran-2-ylmethyl)-N-ethylaniline was developed. The compound was used in the synthesis of new N-derivatives of aromatic amines containing vicinal aminoalcohol moieties.     

Triterpene Glycosides from <Emphasis Type="Italic">Kalopanax septemlobum</Emphasis>. II. Glycosides E,K, and L from Leaves of <Emphasis Type="Italic">Kalopanax septemlobum</Emphasis> var. <Emphasis Type="Italic">maximowiczii</Emphasis> Introduced to Crimea

The known hederagenin 3-O-β-D-glucopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→ 3)-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-arabinopyranoside (sapindoside C) and its 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl and 28-O-α-L-rhamnopyranosyl-(1→4)-O-6-O-acetyl-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl esters, new triterpene glycosides, were isolated from leaves of Kalopanax septemlobum var. maximowiczii introduced to Crimea. The structures of these compounds were established using chemical methods and two-dimensional NMR spectroscopy.__________Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 260–262, May–June, 2005.     

Mechanism of OH radical-induced oxidation of <Emphasis Type="Italic">p</Emphasis>-cresol to <Emphasis Type="Italic">p</Emphasis>-methylphenoxyl radical

The OH radical-induced oxidation of p-cresol to p-methylphenoxyl radical was studied in aqueous solution in a wide pH range by means of pulse radiolysis combined with optical spectroscopy. OH-adduct cyclohexadienyl type radicals were identified as intermediates of the reaction. In the acidic pH range the first-order rate coefficient of phenoxyl radical formation was found linearly dependent on the H₃O⁺ concentration yielding a bimolecular rate coefficient of 1.8 × 10⁸ mol^–1 dm³ s^–1. In the alkaline range a linear dependence was found on the OH^– concentration with rate coefficient of 4.9 × 10¹⁰ mol^–1 dm³ s^–1. These findings were interpreted in terms of acid-base catalysis of the H₂O elimination from the OH-adduct. With the time resolution applied, 30 ns, the radical cation p-CH₃C₆H₄OH^+. was not observed as intermediate.     

<Emphasis Type="Italic">Raman</Emphasis> Spectroscopy and <Emphasis Type="Italic">Ab-Initio</Emphasis> Model Calculations on Ionic Liquids

Summary. A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C₄ mim][X]) salts. The rotational isomerism of the [C₄ mim]⁺ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the “localized structure features” that apparently exist in ionic liquids are described. It is hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-Alkenylanilines: VII. Synthesis of Indole Heterocycles from Products of Reaction between <Emphasis Type="Italic">N</Emphasis>-Mesyl-2-(1-alken-1-yl)anilines and Halogens

N-Mesyl-2-(1-methyl-1-butenyl)-6-methylaniline reacted with Br₂ to afford N-mesyl-2-(3-bromo-1-penten-2-yl)aniline that under treatment with NH₃ or amines underwent cyclization into N-mesyl-7-methyl-3-methylene-2-ethylindoline. The reaction of N-mesyl-2-(1-methyl-1-buten-1-yl)-4-methyl- and 2-(1-methyl-1-buten-1-yl)aniline with Br₂ gave rise to the corresponding N-mesyl-2-(2-bromo-1-methyl-1-buten-1-yl)anilines. Under the similar conditions N-tosyl-2-(1-cyclohexen-1-yl)aniline was converted into N-tosyl-2-(6-bromo-1-cyclohexen-1-yl)aniline that under treatment with NH₃ furnished N-tosyl-1,2,3,9a-tetrahydrocarbazole. The reaction of N-mesyl-1,2,3,9a-tetrahydrocarbazole with CuBr₂ in MeOH afforded N-mesyl-4-methoxy-1,2,3,4-tetrahydrocarbazole. N-Mesyl-6-methyl-2-(1-cyclopenten-1-yl)aniline in reaction with Br₂ in the presence of NaHCO₃ was oxidized into the corresponding cyclopentenone, and with NBS it gave N-mesyl-2-(2-bromo-1-cyclopenten-1-yl)aniline.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 730–737.Original Russian Text Copyright © 2005 by Gataullin, Sotnikov, Spirikhin, Abdrakhmanov.     

A novel method for <Emphasis Type="Italic">N</Emphasis>-alkylation of aliphatic amines with ethers over γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

A novel and simple method for the N-alkylation of amines with different ethers as alkylating reagents has been developed, using cheap γ-Al₂O₃ as the catalyst at atmospheric pressure in the temperature range of 260–320°C. For example, the reaction of equimolar amounts of morpholine and diethyl ether gave N-ethylmorpholine quantitatively. The present catalytic system is applicable to the N-alkylation of both primary and secondary amines. Since only water is generated as byproduct, the protocol proved to be eco-friendly and atom-economic.     

Reaction sites of <Emphasis Type="Italic">N,N′</Emphasis>-substituted <Emphasis Type="Italic">p</Emphasis>-phenylenediamine antioxidants

The geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable N_B=C_X structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness. Dedicated to Professor Vladimír Kvasnička, DrSc., in honour of his 65th birthday     

Infrared spectra of Hoffmann-<Emphasis Type="Italic">T</Emphasis><Subscript><Emphasis Type="Italic">d</Emphasis></Subscript>-type benzene clathrates

Six new title compounds in the form of Cd(cyclobutylamine)₂M′(CN)₄ · 2G (M′ = Cd or Hg; G = benzene, 1,2-dichlorobenzene, or 1,3-dichlorobenzene) have been prepared in powder form. Their spectral data were found to be consistent with the structure of the Hofmann-T _d -type clathrates.     

Kinetic Isotope Effect in the Photoreduction of <Emphasis Type="Italic">o</Emphasis>-Benzoquinones in the Presence of <Emphasis Type="Italic">N,N</Emphasis>-Dimethylaniline

The kinetics of photoinduced reduction of a series of 3,5- and 3,6-di-tert-butylbenzoquinones-1,2 was studied in the presence of N,N-dimethylaniline, its deuterated analog, and a series of para-substituted N, N-dimethylanilines. On passing from the endothermic to the exothermic range of the free energy of electron transfer ΔG _e , the effective rate constants k _H and k _D and the quantum yields ϕ_H and ϕ_D of the reaction varied nonmonotonically with a maximum at ΔG _e of approximately +0.1 eV. For the reactant pairs relevant to the ascending (left-hand) branch of the plot k _H = f(ΔG _e ), the H/D isotope effect takes place, varying from two to five in magnitude. For the reactant pairs at the maximum and in the descending (right-hand) branch of the plot k _H = f(ΔG _e ), there is no isotope effect or its value is insignificant.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 5, 2005, pp. 348–352.Original Russian Text Copyright © 2005 by Abakumov, Shurygina, Chesnokov, Druzhkov, Lopatin, Chechet, Cherkasov.     

Structure of Galactomannans from <Emphasis Type="Italic">Gleditsia delavayi</Emphasis> and <Emphasis Type="Italic">G. aquatica</Emphasis> by <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR Spectroscopy

The structure of galactomannans isolated from seeds of G. delavayi and G. aquatica was studied by ¹H and ¹³C NMR spectroscopy. It was found that the galactomannans consisted mainly of β-1-4-bound mannopyranoses, a part of which was substituted on the C-6 hydroxyl by terminal units of α-galactopyranose.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 12–13, January–February, 2005.     

Structural analysis of <Emphasis Type="Italic">w</Emphasis>/<Emphasis Type="Italic">o</Emphasis>/<Emphasis Type="Italic">w</Emphasis> multiple emulsions by means of DSC

Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are beneficial during manufacturing as in process controls, or to ensure product quality.