Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

<Emphasis Type="Italic">o</Emphasis>-Semiquinone metal complexes as derivatives of sterically hindered di-<Emphasis Type="Italic">o</Emphasis>-quinone

ESR spectroscopy was used to study a series of mono- and binuclear o-semiquinone metal complexes, viz., derivatives of sterically hindered di-o-quinone 1,2-bis(2,5-di-tert-butylcyclohexadiene-1,5-dion-3,4-yl)ethane (1). Hindered rotation was found in the o-semiquinone moiety of the generated complexes. Magnetochemical measurements for polymeric bis(o-semiquinolate)copper(II) based on di-o-quinone 1 showed two antiferromagnetic channels of interaction between the paramagnetic centers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1580–1584, July, 2005.     

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.     

Enthalpies of mixing of <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">m</Emphasis>-isomers at 298.15 K

Excess enthalpies (H ^E) of 17 binary mixtures of o- and m-isomers of dichlorobenzene, difluorobenzene, methoxymethylbenzene, dimethylbenzene, dimethoxybenzene, aminofluorobenzene, fluoronitrobenzene, diethylbenzene, chlorofluorobenzene, fluoroiodobenzene, bromofluorobenzene, chloromethylbenzene, fluoromethylbenzene, bromomethylbenzene, iodomethylbenzene, fluoromethoxybenzene, dibromobenzene at 298.15 K were measured. All excess enthalpies measured were very small, and those of o-+m-isomers of aminofluorobenzene, dibromobenzene and iodomethylbenzene were negative but 14 other binary mixtures of isomers were positive over the whole range of mole fractions. H ^E of o-+m-isomers of dimethoxybenzene showed the largest enthalpic instability and those of aminofluorobenzene showed the largest enthalpic stability. There was a correlation between dipole–dipole interaction, dipole–induced dipole interaction or entropies of vaporization and excess partial molar enthalpies at infinite dilution.     

Copolymers and two-layered composites of poly(<Emphasis Type="Italic">o</Emphasis>-aminophenol) and polyaniline

Electroactive conducting copolymers of aniline (ANI) and o-aminophenol (OAP) and two-layered poly(o-aminophenol) (POAP)/polyaniline (PANI) composites were prepared in aqueous acidic solution by electrode potential cycling. Copolymerization was carried out at different feed concentrations of OAP and ANI on a gold electrode. A strong inhibition of electropolymerization was found at a high molar fraction of OAP in the feed. The copolymers showed good adherence on the electrode surface and gave a redox response up to pH=10.0. Two transitions were observed in the in situ conductivities of the copolymers (as with PANI), but the conductivities were lower by 2.5–3 orders of magnitude as compared to PANI. Electrosynthesis of PANI on POAP modified electrodes showed copolymer formation after reaction initiation and finally formation of a PANI layer at the copolymer/solution interface. The ‘memory effect’ of the bilayer structures of both polymers was discussed in terms of protonation/deprotonation and anion consumption taking place during redox processes of both polymers.     

Activation and reaction volumes of the reactions of <Emphasis Type="Italic">o</Emphasis>-and <Emphasis Type="Italic">p</Emphasis>-nitrophenylsulfenyl chlorides with styrene and cyclohexene in some solvents

The effect of hydrostatic pressure below 1000 kg cm⁻² on the rate of reactions of o-and p-nitrophenylsulfenyl chlorides with styrene and cyclohexene was studied. The activation and reaction volumes (cm³ mol⁻¹) for the reactions of o-nitrophenylsulfenyl chloride with styrene in acetonitrile (−23.1 and −23.6), 1,2-dichloroethane (−29.2 and −24.7), chlorobenzene (no, −20.2), and anisole (−25.1 and −21.2) and for the reaction of p-nitrophenylsulfenyl chloride with styrene in carbon tetrachloride (−39.5±1.5 and −22.0) were determined. In carbon tetrachloride the activation volumes for the reactions of cyclohexene with o-and p-nitrophenylsulfenyl chlorides (−37.7±2.0 and −40.9±1.2 cm³ mol⁻¹, respectively) are almost the same and coincide with the data for the reactions with styrene. The considerable decrease in the volume of the transition state in the nonpolar solvent is considered as a consequence of the enhanced electrostriction of carbon tetrachloride in the solvate sphere of the transition state of the reaction, which excludes the nonpolar transition state of the sulfuran type. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 477–480, March, 2007.     

Palladium deposition features on poly-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine film

Palladium electrodeposition on poly-o-phenylenediamine (PPD) redox polymer was studied. Palladium electrodeposition was shown to be initiated at the ITO/polymer interface with further proliferation into the polymeric matrix and passing by mediator mechanism. PPD exposure to PdCl₂ solution was shown to result in the accumulation of palladium ions in the polymer matrix with partial substitution of counter ions linked to nitrogen atom. Upon rinsing, the film retains some palladium ions, which can be reduced to metal. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 8, pp. 1035–1039. The text was submitted by the authors in English.     

Study on Inclusion Complex Formation of <Emphasis Type="Italic">m</Emphasis>-Aminobenzoic Acid with Native and Substituted <Emphasis Type="Italic">β</Emphasis>-Cyclodextrins

The complex formation of native and substituted β-cyclodextrins with m-aminobenzoic acid in water was characterized by calorimetry, ¹H NMR and UV spectroscopic studies. These studies showed that β-, hydroxypropyl-β- and methyl-β-cyclodextrins form 1:1 inclusion complexes with m-aminobenzoic acid. The thermodynamic properties of complex formation (K,Δ_c G ^o,Δ_c H ^o,Δ_c S ^o) were calculated. It was found that the processes of complexation are mainly favorable entropically. Introduction of hydroxypropyl- and methyl-substituents into the β-CD molecule results in negligible enhancement of stability of the complexes formed. The structure of these substituents has no influence on the stability constant values. The insertion of the carboxylic group of m-aminobenzoic acid into the cyclodextrin cavity was confirmed by ¹H NMR data.     

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.     

Electrochemical transformations and anti/prooxidant activity of sterically hindered <Emphasis Type="Italic">o</Emphasis>-benzoquinones

The electrochemical properties of a series of sterically hindered o-benzoquinones in aprotic solvents were examined. The reaction of O₂ and KO₂ with o-benzoquinones and electrogenerated o-semiquinone radical anions was studied. The formation of o-semiquinone radical anions in the reactions of KO₂ with the studied o-quinones was detected using UV-visible and ESR spectroscopy. The influence of the test compounds on lipid peroxidation was considered at the molecular and tissue levels in vitro. In the most cases, o-quinones exhibit antioxidant activity, which varies depending on the type of lipid substrate.     

Synthesis of substituted benzoxazinylthieno[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridines by the reaction of (3-cyanopyridin-2-ylthio)acetic acids or their amides with <Emphasis Type="Italic">o</Emphasis>-aminophenyl(diphenyl)carbinol

A general method for the synthesis of 3-amino-2-(4,4-diphenyl-4H-3,1-benzoxazin-2-yl)thieno[2,3-b]pyridines was proposed. The method involves reactions of (3-cyanopyridin-2-ylthio)acetic acids or their amides with o-aminophenyl(diphenyl)carbinol in nitromethane in the presence of perchloric acid followed by neutralization of the resulting salts.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2759–2762, December, 2004.     

Kinetics of oxidative ammonolysis of 4-bromo-<Emphasis Type="Italic">o</Emphasis>-xylene: I. Transformations of 4-bromo-<Emphasis Type="Italic">o</Emphasis>-xylene and 4-bromo-<Emphasis Type="Italic">o</Emphasis>-tolunitrile

Kinetic laws of 4-bromo-phthalonitrile synthesis by vapor-phase oxidative ammonolisis of 4-bromo-o-xylene in the range of 633–69 K were studied. It was shown that formation of 4-bromophthalonitrile proceeds successively through 4-bromo-o-tolunitrile. Conversion rates of 4-bromo-o-xylene and 4-bromo-o-toluinitrile were found to be described by half-order equations on the corresponding components and not to depend on the oxygen and ammonia concentrations.     

Study of the mechanism of redox transformations of sterically hindered <Emphasis Type="Italic">N</Emphasis>-aryl-<Emphasis Type="Italic">o</Emphasis>-iminoquinones

The mechanisms of redox transformations of sterically hindered [¹IBQ]-[³IBQ], 9,10-iminophenanthraquinone [⁴IFQ], and o-aminophenol [⁵AP] have been studied by cyclic voltammetry. It has been shown that the reduction process in tetrahydrofuran consists of two consecutive reversible steps leading to the formation of a radical anion and a dianion. In the case of acetonitrile, only the first redox process is detected, which involves the steps of protonation and electron addition resulting in the formation of a monoanion. Quantum-chemical calculations indicate a lower degree of participation of the six-membered nonaromatic carbon ring in the spin density delocalization in the o-iminosemiquinonate radical anions as compared to o-benzosemiquinonate radical anions. The oxidation of iminoquinones results in the formation of an unstable radical cation, which undergoes further chemical transformations. An increase in the acidity of a medium leads to the formation of protonated forms with the reduction potential being shifted anodically. The introduction of screening groups makes it possible to suppress side reactions of hydrolysis and cyclization of oxidized o-aminophenol [⁵AP] forms. Therefore, the major product of complete electrolysis is o-iminobenzoquinone [²IBQ].     

Synthesis of isomeric 2-oxazolidinones from (1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">R</Emphasis>)-and (1<Emphasis Type="Italic">S</Emphasis>,2<Emphasis Type="Italic">S</Emphasis>)-2-amino-1-(4-nitrophenyl)-1,3-propanediols

A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds was studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007.     

Synthesis of 3-acetyl-6-(<Emphasis Type="Italic">o</Emphasis>-methyl benzoyl)-<Emphasis Type="Italic">N</Emphasis>-ethylcarbazole

3-Acetyl-6-(o-methyl benzoyl)-N-ethylcarbazole was prepared through successive o-methyl benzoylation and acetylation of N-ethylcarbazole in one pot. The overall yield was 85.6% and the structure was confirmed by ¹H-NMR and ¹³C-NMR. A preliminary investigation had also been carried out on the mechanism of the o-methyl benzoylation of N-ethylcarbazole.     

Aryltetralin Lignans from <Emphasis Type="Italic">Linum mucronatum</Emphasis> Bertol. ssp. <Emphasis Type="Italic">mucronatum</Emphasis>

The dried and aerial part of Linum mucronatum ssp. mucronatum was analyzed by gas chromatography-mass spectrometry (GC-MS). Two aryltetralin lignans, podophylloyoxin, 6-methoxypodophylloyoxin, and β-peltatin, were identified. This is the first report of the analysis of L. mucronatum ssp. mucronatum.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 24–25, January–February, 2005.     

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     

Chemotaxonomy of <Emphasis Type="Italic">Ballota</Emphasis> Species

Sixteen taxa of Ballota were investigated by analyzing the contents of diterpenoid and flavonoid compositions, and the relationships were compared with their morphological properties. HPLC chromatograms of diterpenoids and flavonoids from acetone extracts of sixteen Ballota taxa revealed the presence of thirteen compounds. Isolated compounds from Ballota species were evaluated by the unweighted pair-group arithmetic average (UPGMA) clustering method. B. glandulosissima is distinct from all other taxa in the dendogram, and this species is morphologically different from other taxa by having a high number of glandular hairs. The second group is composed of B. saxatilis ssp. saxatilis and B. inaequidens; these two species are in close kinship as evidenced by their morphology (similar calyx shape). In the latter clusters at most, the affinities among taxa, as suggested by diterpenoid and flavonoid pattern, are only partially congruent with affinities based on other evidence. In general, morphologic, anatomic characters, distributions, and habitats are not concordant with the clusters. Also, no concordance was found between the sections, phylogenetic order [1], and those of the groups formed by cluster analyses.__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 242–244, May–June, 2005.     

Synthesis of 2,3-<Emphasis Type="Italic">cis</Emphasis> Stereomeric Emetamines <Emphasis Type="Italic">via Reissert</Emphasis> Compounds

Summary. Alkylation of Reissert compounds with certain benzoquinolizinone derivatives followed by hydrolytic cleavage afforded the core of the title compounds in a two step sequence. Finally, the lactam intermediates were reduced with DIBAH giving the target compounds, the structural and stereochemical assignments of which were achieved by ¹³C NMR spectroscopy. Part of PhD thesis, LMU München, D     

<Emphasis Type="Italic">O</Emphasis>- and <Emphasis Type="Italic">N</Emphasis>-Alkylation of <Emphasis Type="Italic">N</Emphasis>-halosuccinimides in ionic reactions with 1-phenyltricyclo [4.1.0.0<Superscript>2,7</Superscript>]heptane

N-Bromo and N-chlorosuccinimides add to 1-phenyltricyclo[4.1.0.0^2,7]heptane in CH₂Cl₂ with cleavage of the C(1)-C(7) bond to give isomeric 1 : 1 Markownikoff-type endo, anti-adducts of the norpinane structure in a ∼3 :7 ratio corresponding to N and O alkylation of succinimide.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No.2, pp. 457–460, February, 2005