Latent ruthenium carbene complexes with six-membered N- and S-chelate rings

New ruthenium carbene complexes with chelating N- and S-benzylidene ligands were synthesized by the reactions of second- and third-generation Grubbs catalysts with ortho-vinylbenzyl-substituted amines or sulfides. These complexes were shown to exhibit catalytic activity in ring-opening metathesis polymerization and ring-closing metathesis.     

Cobalt and manganese complexes with redox-active ligands in polymerization of acrylonitrile and methyl methacrylate

The influence of bis[4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-iminobenzosemiquinonato]cobalt(ii) and 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzosemiquinonato]-[4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolate]manganese(iii) on polymerization of methyl methacrylate and acrylonitrile in the presence of azobisisobutyronitrile (as a traditional radical initiator) and alkyl halides (used for initiation of controlled atom transfer radical polymerization process) was studied. The effect of the nature of the activating agents (amines) and the temperature conditions on the overall polymerization rate of the indicated monomers, as well as molecular weight characteristics of the synthesized polymers, were analyzed. The optimal conditions for the synthesis of polyacrylonitrile and poly(methyl methacrylate) with a relatively narrow molecular weight distribution were selected.     

Synthesis of Dicarboxylic Acid Amides and Diamides on the Basis of [4-(4-Methoxyphenyl)tetrahydro-2<Emphasis Type="Italic">H</Emphasis>-pyran-4-yl]methanamine

The condensation of various nonaromatic amines with ethyl N-{[4-(4-methoxyphenyl)tetrahydro-2H-pyran-4-yl]methyl}oxamate prepared from [4-(4-methoxyphenyl)tetrahydro-2H-pyran-4-yl]methanamine and diethyl oxalate afforded the corresponding N,N'-disubstituted oxamides. N-Aryloxamides were synthesized by the reaction of [4-(4-methoxyphenyl)tetrahydro-2H-pyran-4-yl]methanamine with ethyl N-aryloxamates. The condensation of N-{[4-(4-methoxyphenyl)tetrahydro-2H-pyran-4-yl]methyl}succinamic acid with primary amines gave N,N'-disubstituted siccinamides.     

Cycloaminomethylation of dihydric phenols catalyzed by <Emphasis Type="Italic">d</Emphasis>- and <Emphasis Type="Italic">f</Emphasis>-metal compounds

An efficient method has been developed for the synthesis of 7,16,25-triaryl-7,8,16,17,25,26-hexahydro-6H,15H,24H-tribenzo[f,m,t][1,5,8,12,15,19,3,10,17]hexaoxatriazacyclohenicosines, 3,8-diaryl-2,3,4,7,8,9-hexahydrobenzo[1,2-e:4,3-e′]bis[1,3]oxazines, 3,9-bis(chlorophenyl)-3,4,9,10-tetrahydro-2H,8H-benzo[1,2-e:3,4-e′]bis[1,3]oxazines, and 2,9-bis(chlorophenyl)-1,2,3,8,9,10-hexahydrobenzo[1,2-e:6,5-e′]bis-[1,3]oxazines via cycloaminomethylation of pyrocatechol, resorcinol, and hydroquinone with N,N-bis(methoxymethyl) anilines in the presence of samarium catalysts.     

Exchange reactions of urethanes with proton-donating compounds: Kinetics of the reactions of phenyl-<Emphasis Type="Italic">N</Emphasis>-phenylurethane with butyl alcohols

The exchange reactions of phenyl-N-phenylurethane with aliphatic alcohols, namely, n-butyl, sec-butyl, and tert-butyl alcohols, in ortho-dichlorobenzene and in the media of the corresponding alcohols were studied. In the absence of a catalyst and proton-donating compounds, the monomolecular cleavage of phenyl-N-phenylurethane to isocyanate and alcohol proceeds at a noticeable rate starting only at 250°C. Between 40 and 80°C, the exchange reactions take place via direct exchange between urethane and the photon-donating compound and are second-order up to high conversions (until the almost complete disappearance of the initial urethane). Activation energies and apparent rate constants have been determined for the exchange reactions of phenyl-N-phenylurethane with butyl alcohols. The rates of the exchange reactions in the alcohol medium are compared with those in ortho-dichlorobenzene.     

Specific features of radical copolymerization of methyl methacrylate and <Emphasis Type="Italic">n</Emphasis>-butyl acrylate in the presence of the tributylborane–<Emphasis Type="Italic">p</Emphasis>-quinone system

Copolymerization of methyl methacrylate (MMA) and n-butyl acrylate (n-BA) in the presence of the tributylborane–p-quinone system has been investigated. Reactivity ratios of the monomers differ from the values known for conventional radical polymerization. The copolymerization proceeds in a controlled manner according to the reversible inhibition mechanism. The nature of p-quinone and the composition of the monomer mixture affect the realization of this mechanism. The microstructure of the copolymers obtained in the presence of borane and p-quinones depends on the nature of the latter.     

Methodology of simple quantum chemical estimation of solid-phase heats of formation with constant intermolecular interactions over the series of compounds (by the example of quinones)

Heats of formation for some quinone compounds, including both 1,2-quinones and 1,4-quinones, are calculated. Linear correlations, uniform for all the compounds studied, which relate the experimentally calculated in the solid state and quantum chemically calculated gas phase standard heats of formation are found. The correlation coefficient values for all the dependences found exceed 0.98. The electron density distribution in 1,2-benzoquinone and 1,4-benzoquinone molecules is investigated using DFT at the B3LYP/6-311++G(3df,3pd) theory level using the NBO-analysis. Essential common features of the electronic distribution in the above molecules are stated, which serves as a premise for a constant contribution of the crystal field effect to the heats of formation of ortho-and para-quinones. On the whole, by the example of quinones we develop a methodology for a simple theoretical estimation of the solid phase (and also in any condensed state) heats of formation of chemical compounds under the condition of approximately constant intermolecular interactions in the series in question.     

Addition of phthalimide and acetone to phosphorylated methylene quinones

New method for synthesis of phosphorylated methylene quinones via bromination of the sterically hindered phenol [prepared via benzylation of secondary chlorophosphines with 4-(methoxymethyl)-2,6-di-tert-butylphenol] with N-bromosuccinimide followed by dehydrobromination with trimethyl orthoformate has been developed. Tertiary phosphine oxides containing the fragment of sterically hindered phenol and amine or acetonyl group have been synthesized for the first time in the reaction of phosphorylated methylene quinones with N- and C-nucleophiles.     

Epoxidation and Heterocyclization of Arenesulfonamides of the Norbornene Series

Reactions of previously known and newly synthesized N-(bicyclo[2.2.1]hept-5-en-endo-2-ylmethyl)arenesulfonamides with monoperoxyphthalic acid generated in situ from phthalic anhydride and 30% hydrogen peroxide lead mostly to the corresponding N-arylsulfonyl-exo-2-hydroxy-4-azatricyclo[4.2.1.0^3,7]nonanes (azabrendanes). In some cases, N-(exo-5,6-epoxybicyclo[2.2.1]hept-5-en-exo-2-ylmethyl)arenesulfonamides were isolated as the only products or mixtures of alternative oxidation products were obtained. The presence of electron-acceptor nitro groups in the benzene ring and bulky substituents, primarily in the ortho position, is considered to be a structural factor preventing the primary oxidation products (epoxy derivatives) from undergoing heterocyclization.     

Voltammetric determination of pyrocatechol at a mechanically renewed electrode made of a graphite-epoxy composite

The reversibility of a two-electron pyrocatechol/o-benzoquinone system (ΔE _p = 28 ± 1 mV) is found by cyclic voltammetry at a mechanically renewed electrode from a graphite-epoxy composite. The closeness of the found and theoretical values of ΔE _p indicates the high electrochemical activity of the graphite-epoxy composite electrode renewed in situ by cutting a thin surface layer. The potentials of pyrocatechol anodic and cathodic peaks are proportional to E ₀ ± 0.059pH in the pH range of 1–9. The pyrocatechol anodic and cathodic peak currents remain linear functions of pyrocatechol concentration in the concentration range from 0.01 to 0.08 and from 0.08 to 0.9 g/L, respectively. A procedure for the voltammetric determination of pyrocatechol in its individual solutions and in the presence of hydroquinone is proposed. Good precision and the absence of a systematic error in the determination of pyrocatechol by measuring its cathodic peak are demonstrated.     

Synthesis of tertiary amines containing <Emphasis Type="Italic">gem</Emphasis>-dichlorocyclopropane and cycloacetal fragments

Reactions of secondary amines containing gem-dichlorocyclopropane and cycloacetal fragments with allyl chloride, trans-1,3-dichloropropene, benzyl chloride, and chloromethyl-gem-dichlorocyclopropane were studied. The corresponding tertiary amines were obtained in 20–85% yield. Microwave radiation stimulates N-alkylation of the secondary amine containing the heterocyclic moiety. The structures of the tertiary amines prepared were studied. The configuration of the double bond in the trans-1,3-dichloropropene derivative is retained.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl derivatives of 1,4-benzoquinone monoimine with substituted hydrazines

Reaction direction of N-sulfonyl derivatives of 1,4-benzoquinone monoimine with substituted hydrazines depends on the redox potential of the quinone imine and on the basicity of the hydrazine. Aryl (alkyl)hydrazines of high basicity favor the reduction of quinone monoimine. In reactions with less basic aroylhydrazones N'-(4-oxocyclohexa-2,5-dienylidene)aroylhydrazides were obtained only from the alkylsubstituted in the quinoid ring N-sulfonyl derivatives possessing a lower redox potential.     

Synthesis of <Emphasis Type="Italic">ortho</Emphasis>-carboranyl derivatives of (<Emphasis Type="Italic">S</Emphasis>)-asparagine and (<Emphasis Type="Italic">S</Emphasis>)-glutamine

(S)-Asparagine and (S)-glutamine ortho-carboranyl derivatives with free amino and carboxy groups in the α-position were synthesized. By an example of N ^γ-(1,2-dicarba-closo-dodecarboran-3-yl)-(S)-glutamine it was demonstrated that the developed synthetic approach carboranyl derivatives of amino acids allowed the preparation of optically pure isomers.     

Arylation of adamantanamines: VIII. Optimization of the catalytic system for copper-catalyzed arylation of adamantane-containing amines

Arylation of adamantane-containing amines with iodobenzene in the presence of copper(I) and copper(II) compounds and various N,N-, N,O- and O,O-bidentate ligands was studied. The best results were obtained using the catalytic system CuI–rac-BINOL [1,1′-bi(naphthalen-2-ol)] (10/20 mol %). Reactions with iodobenzene derivatives containing electron-donor and electron-withdrawing substituents in the para position to the iodine atom were carried out under the optimal conditions.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl-1,4-benzoquinone imines with sodium azide

Depending on the conditions and the order of addition of the reactants, reactions of N-sulfonyl-1,4-benzoquinone imines with sodium azide afforded N-(3-azido-4-hydroxyphenyl)alkane(arene)sulfonamides, N-(3-azido-4-oxocyclohexa-2,5-dienylidene)alkane(arene)sulfonamides, and N-(3,5-diazido-4-hydroxyphenyl)-alkanesulfonamides. Quantum chemical calculations showed that the reactions begin with addition of azide ion to the quinone imine.     

Polymerization of methyl methacrylate in the presence of <Emphasis Type="Italic">o</Emphasis>-iminoquinones: Reversible and irreversible inhibition

New regulators of radical polymerization of methyl methacrylate based on N-(aryl)-o-iminoquinones of various structures are proposed. It is shown that samples of polymethylmethacrylate with the participation of N-(aryl)-o-iminobenzoquinones could be used as macroinitiators of polymerization. Optimal conditions to synthesize polymers in the presence of o-iminobenzoquinones are determined, which make it possible to obtain polymethylmethacrylate with a polydispersity coefficient of no more than 1.5 on deep conversions during bulk polymerization.     

Synthesis and application of <Emphasis Type="Italic">N</Emphasis>-hydroxy(tetrahydrofuran-2-yl)amines

Data on synthesis, reactivity and bioactivity of N-hydroxy(tetrahydrofuran-2-yl)amines were discussed in the present review. General approaches to chiral N-glycosylhydroxylamines based on reactions of hydroxylamine with cyclic five-membered hemiacetals or dihydrofurans as well as reactions of tetrahydrofuran-containing nitrones with nucleophiles were systematized. The application of N-hydroxy(tetrahydrofuran-2-yl)amines in the synthesis of chiral heterocycles, aminophosphonic acids, N-hydroxypropargylamines, as well as natural compounds (for example, sieboldin A), pharmaceuticals (Zileuton) and their analogs was demonstrated. It was found that depending on substituents, N-hydroxy(tetrahydrofuran-2-yl)-amines can act as lipoxygenase inhibitors, and show antioxidant, antitumor, antibacterial, and other types of activities.     

Synthesis and reduction of <Emphasis Type="Italic">N</Emphasis>-substituted 5-nitrosoquinolin-8-amines

N-Substituted 5-nitrosoquinolin-8-amines were synthesized for the first time by amination of 5-nitrosoquinolin-8-ol with primary aliphatic amines. The amination of 5-nitrosoquinolin-8-ol with hexamethylenediamine afforded N¹,N⁶-bis(5-nitrosoquinolin-8-yl)hexane-1,6-diamine. The resulting nitrosoquinolinamines were reduced with hydrazine hydrate over Pd/C to N⁸-alkylquinoline-5,8-diamines and N¹,N⁶-bis-(5-aminoquinolin-8-yl)hexane-1,6-diamine.     

Radiation polymerization of methacrylates controlled by a chain transfer catalyst

The effect of γ-radiation dose and chain transfer catalyst on polymerization of methyl methacrylate (MMA) and copolymerization of MMA with hydroxyethyl methacrylate or triethylene glycol dimethacrylate has been investigated. The addition of 5 × 10^?4?10^?3 mol/L of bis[(difluoroboryl) isopropylpyridine dimethylglyoximato]cobalt(II) (Co(II)) makes it possible to produce macromonomers MM _n ⁼⁼ bearing terminal double bonds and having a degree polymerization of n = 2?40 and a polydispersity index of 1.05?1.15. It has been found that the degree polymerization of the macromonomers increases with the increasing γ-radiation dose and monomer conversion through the mechanism of the reversible β-cleavage of the terminal unit: R _k ^? + MM _n ⁼ ? MM _k+1 ⁼ + R _n-1 ^? followed by the living polymerization of both radicals. This reaction may compete with the catalytic chain transfer reaction and have a significant effect on the evolution of the molecular weight characteristics of the macromonomers during the course of MMA (co)polymerization.     

New functionalization opportunities for <Emphasis Type="Italic">peri</Emphasis>-hydroxynaphthoyl and <Emphasis Type="Italic">peri</Emphasis>-fused heterocyclic compounds

A capability was studied of hydrogenated α-pyrone heterocycle in 7-methoxy-4-(4-methoxy-phenyl)-3,4-dihydro-2H-benzo[h]chromen-2-one to undergo aminolysis under the treatment with hydrazine hydrate, primary and secondary aliphatic and aromatic amines. A new approach was developed to the preparation of perihydroxyketone of naphthalene series containing a specific functional substituent in the ortho-position with respect to hydroxy group. The effect was revealed of an acetyl group in the position 9 of 7-methoxy-4-(4-methoxyphenyl)-3,4-dihydro-2H-benzo[h]chromen-2-one on the reaction of this compound with aliphatic amines and hydrazine hydrate. 9-Methoxy-1-(4-methoxyphenyl)-6-methyl-3H-benzo[de]pyrido[3,2,1-if]cinnolin-3-one [9-methyl-6-methoxy-3-(4-methoxyphenyl)-10,10a-diazapyren-1-one] was obtained, a new bis-peri-fused heteroaromatic system.