Acylation of [B12H12]2− dianion by carboxylic acid halides

The sodium salt of [B₁₂H₁₂]²⁻ dianion reacts with carboxylic acid halides to give a mixture of B-acylated product [B₁₂H₁₁COR]²⁻ and an unstable intermediate, the latter undergoing hydrolysis to form [B₁₂H₁₁OH]²⁻. The ratio of the products formed depends on the nature of the radical R. The reaction mechanism was studied by NMR spectroscopy. A number of novel [B₁₂H₁₁COR]²⁻ compounds were synthesized; their structures were confirmed by NMR and IR spectral data. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 980–985, May, 1998.     

Cetylpyridinium bromide-based oil-in-water microemulsions as a medium for hydrolysis of esters of phosphorus acids in the presence of primary amines

High-resolution ¹H NMR technique with Fourier-transform and pulsed-gradient spin-echo was used to study the structure of oil-in-water microemulsions based on cetylpyridinium bromide. The sizes of microdrops and the distribution of components between the disperse and continuous phases were found. It was shown for the hydrolytic decomposition of O,O-bis-(p-nitrophenyl) methyl phosphonate in the presence of amines that the microemulsion medium can affect both the rate and mechanism of hydrolysis. The reaction rate constants depend on the structure of microdrops.     

Efficient coupling of heteroaryl halides with arylboronic acids in the presence of a palladium-tetraphosphine catalyst

Cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane:·1/2[PdCl(C₃H₅)]₂ system catalyses the Suzuki cross-coupling of heteroaryl halides with a range of arylboronic acids with very high ratio substrate/catalyst in good yields. Substrates such as pyridines, quinolines, thiophenes, an indole, pyrimidines or a furane have been used successfully.     

Phosphorylformonitrile oxides as spin traps for carbon-centered free radicals: co-formation with radicals in the generation of nitrile oxides from <Emphasis Type="Italic">C</Emphasis>-phosphorylformohydroximoyl halides in the presence of alcohols or ethers

One-electron oxidation of the oximes R₂P(=O)C(=NOH)X (X = Cl or Br) generates the nitrile oxides R₂P(=O)C⁺=NO⁻, which serve as spin traps for unstable carbon-centered radicals.The latter are generated upon addition of PbO₂ to a mixture of formohydroximoyl halide with an alcohol or an ether of the general formula R¹OCHR²R³ under the action of atomic chlorine (bromine) released during the generation of nitrile oxide. This gives rise to new, more persistent C phosphoryliminoxyls R₂P(=O)C(=NO^·)C(OR¹)R²R³ (R¹, R², R³ = H, Alk). When primary alcohols (R¹ = R² = H) are used, acyl radicals generated at the initial step of the reaction are also trapped by nitrile oxides to give C-acyl-C phosphoryl iminoxyl radicals R₂P(O)C(=NO^·)C(=O)R³. Hyperfine coupling constants for more than 20 C-phosphoryl-iminoxyls existing in solutions as mixtures of Z- and E-isomers were determined.The effect of the structure of the primary radical (length of the carbon chain, degree of branching, the presence of a ring, and its size) on the radiospectroscopic characteristics of new C-phosphoryliminoxyl radicals was studied.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 336–341, February, 2005.     

Diastereoselective bromination of(R)-N-cinnamoyl-4-phenyloxazolidin-2-one in the presence of Lewis acids

The stereochemistry of addition of Br₂ toE-andZ-(R)-N-cinnamoyl-4-phenyloxazolidin-2-ones was studied. It was established that both theE-andZ-isomers give only two out of four possible diastereoisomers in the presence of Lewis acids (BPr₃ or AlBr₃). The absolute configurations of the diastereoisomers [(2S', 3R') and (2R', 3S') of the side chain] were established by X-ray structural analysis. The stereochemistry observed is a consequence of the stepwise bromination and the absence of bridging bromine atoms along the reaction coordinate. In the case of theZ-isomer, the diastereoselectivity of the reaction was high, whereas it is low in the case of theE-isomer. It was suggested that at the first stage of addition of Br₂ at the C=C bond, the attack of the Br⁺ cation occurs at the α position, and the second stage of transfer of Br⁻ occurs with the participation of boron or aluminum complexes in the intermediate state of the bromination reaction. This hypothesis as well as the results of calculations of the initial conformations of the substrates provide an explanation of the regularities observed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1022–1028, May, 1997.     

Identification of intermediates in the reaction of 2-thenyl halides with magnesium

The reaction of 2-thenyl chloride with magnesium was shown by the ESR method to proceedvia the intermediate formation of radicals and radical ion pairs, whereas similar reactions of 2-thenyl bromide and iodide occur through the formation of free radicals only. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1556–1559, September, 2000.     

Di-4(3H)-quinazolinon-2-yl Derivatives from the Diacid Chlorides of Pinic and sym-Homopinic Acids

The corresponding diamides have been synthesized by the interaction of the diacid chlorides of cis-2,2-dimethyl-3-carboxycyclobutaneacetic acid (pinic acid) and cis-2,2-dimethylcyclobutane-1,3-diacetic acid (sym-homopinic acid) with two equivalents of anthranilic acid. Treatment of the diamides with formamide gave 2,2-dimethyl-1-[4(3H)-quinazolinon-2-yl]methyl-3-[4(3H)-quinazolinon-2-yl]cyclobutane and 2,2-dimethyl-1,3-di[4(3H)-quinazolinon-2-ylmethyl]cyclobutane respectively.     

Transformations ofmyo-inositol hexa-O-nitrate under the action of amines

Reactions ofmyo-inositiol hexa-O-nitrate with ammonia and primary amines yield tetrahydroxy-1,4-benzoquinone derivatives,viz., its tetraammonium salt and its diimines, respectively. Reactions with secondary and tertiary amines give salts of rhodizonic acid, which are converted into salts of croconic acid under certain conditions. The reactions with secondary amines involve intermediate formation of radical species, which were dectected by ESR spectroscopy. A scheme for the chemical transformations ofmyo-inositol hexa-O-nitrate under the action of amines was proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2962–2967, December, 1996.     

Supramolecular architecture in the crystals of polyfluorinated homophthalic acids

X-ray diffraction analysis of four perfluorinated homophthalic (2-carboxymethylbenzoic) acids is carried out. In the crystals of 2-carboxymethyl-3,4,5,6-tetrafluorobenzoic acid (1) the chains (1D architecture) form with the usual dimeric carboxylic C(O)OH

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O(HO)C synthon. The aromatic carboxylic group is disordered in the ratio 0.58:0.42 over two positions. In the crystals of 2-(carboxydifluoromethyl)-3,4,5,6-tetrafluorobenzoic (2) and 2-(1-carboxy-2,2,2-trifluoroethyl)-3,4,5,6-tetrafluorobenzoic acids (3) the layers (2D architecture) with dimeric and chain-like synthons C(O)OH...O(HO)C are found. In the crystals of 2-[methoxycarbonyl(difluoromethyl)]-3,4,5,6-tetrafluorobenzoic acid (4) only dimers (0D architecture) form with the chain synthon that incorporates both an ester and a carboxylic group. In the crystals of 1 and 2 intermolecular H-O...π interactions, in the crystals of 4 C-F...π interactions, and in 3 both types of interactions are observed.

     

Synthesis of 9-benzyl-o- and 9-benzyl-m-carboranes containing functional substituents in the benzene ring by electrophilic alkylation ofo- andm-carboranes by the correspondingR-benzyl halides

9-Benzyl-o- andm-carboranes containing NO₂, COOH, COOMe, and COPh groups in thepara-position of the benzene ring were synthesized by the Friedel—Crafts reaction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1138–1140, June, 1995.This study was financially supported by the International Science Foundation (Grant MSE 000).     

New systems for classical nitrosohalogenation of alkenes 1. Reactions of alkenes with ethyl nitrite in the presence of phosphorus halides and thionyl chloride

Studies of nitrosation of norbornene and norbornadiene derivatives and dimethyl tricyclo[4.2.2.0^2,5]deca-3,7-diene-9,10-cis-endo-dicarboxylate demonstrated that nitrosation of alkenes with EtONO-PHal₃, EtONO-POHal₃ (Hal = Cl or Br), and EtONO-SOCl₂ systems can afford nitroso halides in high yields without the formation of by-products (ketones and oximes). The reactions with 5-substituted norbornenes are nonregioselective. The trans dimer of endo-5-trifluoromethyl-cis-exo-2-chloro-3-nitrosobicyclo[2.2.1]heptane was studied by X-ray diffraction. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2070–2080, September, 2005.     

Cyanamides in cyclization reactions with anthranilates, 2-aminophenyl ketones, and methyl 2-(3-oxopiperazin-2-yl)acetate

Cyclization of aryl-, aroyl-, and (4,6-dimethylpyrimidin-2-yl)cyanamides with methyl anthranilates, 2-aminophenyl ketones, and methyl 2-(3-oxopiperazin-2-yl)acetate leads to 2-amino-3,4-dihydroquinazolin-4-one, 2-aminoquinazoline, and 6-amino-1,3,4,8,9,9a-hexahydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione derivatives, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 164–170, January, 2008.     

Kinetics of the Vapor-Phase Decomposition of Mtbe (Methyl Tert-Butyl Ether) over h3pw12o40/sio2

A kinetic study on the vapor-phase MTBE decomposition over H₃PW₁₂O₄₀/SiO₂ was carried out. Possible kinetic mechanisms are proposed and discussed. Rate expressions were ultimately developed after several verification processes.     

Some laws governing the alkylation of 6-tert-butyl-2-methylphenol with methyl acrylate in the presence of a phenoxide

A kinetic scheme of the reaction between 6-tert-butyl-2-methylphenol and methyl acrylate in the presence of an alkali metal phenoxide has been proposed. The rate constants of the elementary steps describing the catalytic mechanism have been calculated. The reaction gives methyl 3-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionate as the only product (Calkylation). The nature of the metal cation does not affect the reaction mechanism.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–507, March, 1993.     

Some transformations of 2-benzylcyclododecanones prepared by alkylation of cyclododecanone with benzyl halides under conditions of phase transfer catalysis

Cyclododecanone is readily alkylated with benzyl halides (ArCH₂X) to give 2-benzylcyclododecanones under conditions of phase transfer catalysis. Under the action of polyphosphoric acid 2-benzylcyclododecanone undergoes cyclization to give 1,2,3,4,5,6,7, 8,9,10-decahydrocyclododeca[b]indene. It also reacts with NOCl to give 12-hydroxyimino-2-benzylcyclododecanone, which enters the Beckmann rearrangement to afford 2-benzyl-1,12-dodecandioic acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 905–907, May, 1993.     

Reaction of β-pinene and thiols in the presence of Lewis acids

The reaction of β-pinene with thiols using zinc chloride catalyst occurred regiospecifically to synthesize pinane-type sulfides and to form anti-Markovnikov addition products. However, the pinane structure isomerized into menthane in the presence of boron trifluoride etherate. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 146–148, March–April, 2006.     

Rapid and mild sulfonylation of aromatic compounds with sulfonic acids via mixed anhydrides using Tf2O

An efficient and direct sulfonylation of aromatic compounds with sulfonic acids is described via mixed anhydrides in short reaction times using Tf₂O in nitromethane at room temperature.     

Chemoselectivity of 6-bromo-2-methyl-3,1-benzoxazin-4-one towards amines,Schiff bases,and azines

Summary 6-Bromo-2-methyl-3,1-benzoxazin-4-one (1) undergoes an unusual cleavage at position 4 when it is allowed to react witho-phenylenediamine or anthranilic acid in dry benzene to give the corresponding compounds2–5, respectively. The reaction of1 withSchiffbases and azines results in the formation of the compounds6a–d and8a,b, respectively. The reaction involves a cleavage of theSchiff base or the azine into its amine and arylidene moieties which are smoothly incorporated into1 via nucleophilic attack of the amine at position 4 and condensation of the aldehyde with a reactive methyl group, at position 2 respectively. No displacement of the arylidene segment was observed.

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Zur Chemoselektivität von 6-Brom-2-methyl-3,1-benzoxazin-4-on gegenüber Aminen,Schiffschen Basen und Azinen

Zusammenfassung 6-Brom-2-methyl-3,1-benzoxazin-4-on reagiert mito-Phenylendiamin oder Anthranilsäure in trockenem Benzol unter einer ungewöhnlichen Bindungstrennung zu den Verbindungen2–5. Die Reaktion von1 mitSchiffschen Basen und Azinen führt zu den Verbindungen6a–d und8a,b. Die Reaktion verläuft über eine Spaltung derSchiffschen Base oder des Azins in ihre Amin- und Arylidenreste, die über einen nucleophilen Angriff des Amins an Position 4 und Kondensation des Aldehyds mit der reaktiven Methylgruppe in Position 2 glatt in1 übergeführt werden. Es wurde kein Arylidenaustausch beobachtet.

     

Kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of amines and polymethylbenzenes

A study of the kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of hydrogen donors (para-substituted N,N-dimethylanilines and polymethylbenzenes) showed that plots of the quantum yield of photoreduction (_H) and apparent reaction rate constant (k _H) vs. oxidation potential of hydrogen donors are extreme. In the presence of amines, k _H and _H increase, as a whole, whereas they decrease in the presence of polymethylbenzenes. In coordinates _H-G _e (G _e is the change in the free energy of electron transfer) for pairs quinone-H donor, _H increases with G _e approaching to zero. For the amine series, this effect is mainly in the exothermic region of G _e (G _e < 0). For the series of polymethylbenzenes, this increase is observed in the endothermic region (G _e > 0).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2381–2385, November, 2004.     

On the bond order of C2 and N2

The commonly adopted bond order values of C₂ and N₂ are critically investigated with a new bond order concept. Ab initio calculations with extended basis sets suggest that C₂ can be described by a double to triple bond closer to acetylene than to ethylene and N₂ by a triple bond. The basis set dependence is discussed. Also a relation between the number of basis functions, MO's and non-vanishing eigenvalues of the bond order parts of the density matrix is presented.