Reaction of 2-chloromethylphenols with enaminones

The reaction of o-(chloromethyl)phenols with enamino ketones afforded a series of 3-acyl- and 3-formyl-4H-chromenes as a result of cascade transformation including [4 + 2]-cycloaddition of enamino ketone to o-quinone methide generated in situ and subsequent elimination of secondary amine.     

Synthesis of new hydrazones based on <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">p</Emphasis>-hydroxybenzohydrazides

o- and p-Hydroxybenzohydrazides reacted with various unsaturated aromatic aldehydes to give the corresponding N′-(hydroxybenzoyl)hydrazones. Inhibitory activity of the obtained hydrazones against cathepsin E was evaluated.     

Compounds of the menthane series. Synthesis of unsaturated primary alcohols with the <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">p</Emphasis>-menthane skeletons

Precursors to terpene alcohols of the o- and p-menthane series (o-cimen-7-ol and o- and p-cimen-9-ols) were synthesized, and their reduction with lithium in ethylenediamine was studied. The reduction of o- and p-cimen-9-ols in the presence of isopropyl alcohol selectively afforded the corresponding 1,4-dihydro derivatives. Under analogous conditions, o-cimen-7-ol was converted into a mixture of unsaturated hydrocarbons. The reduction with lithium in ethylenediamine in the absence of isopropyl alcohol in all cases gave mixtures of menthene alcohols.     

Transformations of 5-chloro-2-hydrazino-4-<Emphasis Type="Italic">p</Emphasis>-tolylsulfonyl-1,3-thiazole

Accessible 2,2-dichloro-1-p-tolylsulfonylethenyl isothiocyanate reacted with hydrazine hydrate to give 5-chloro-2-hydrazino-4-p-tolylsulfonyl-1,3-thiazole whose reactions with thiols and amines followed a complicated pattern. Treatment of 5-chloro-2-hydrazino-4-p-tolylsulfonyl-1,3-thiazole with acetylacetone led to the formation of previously unknown 5-chloro-2-(3,5-dimethyl-1H-pyrazol-1-yl)-4-p-tolylsulfonyl-1,3-thiazole which reacted with O-, S-, and N-centered nucleophiles at the C⁵ atom with high regioselectivity.     

Functionalization of sterically hindered catechol and <Emphasis Type="Italic">o</Emphasis>-benzoquinone with 2,2,6,6-tetramethylpiperidine 1-oxyl

Sterically hindered 4,6-di-tert-butyl-3-formylcatechol and 3,6-di-tert-butyl-o-benzoquinone react with 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl to give new chelate ligands of the o-quinone type bearing a 2,2,6,6-tetramethylpiperidine 1-oxyl neutral radical moiety. Structures of the synthesized compounds were established by ESR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray diffraction analysis.     

Crystalline inclusion complexes of diterpenoid isosteviol with aromatic compounds

Crystalline inclusion complexes of diterpenoid isosteviol (ent-16-ketobeyeran-19-oic acid) with individual benzene, o-, m-, p-xylenes, ethylbenzene, isopropylbenzene, o-and m-nitoranilins, benzaldehyde, styrene and naphthalene are obtained and characterized by single crystal X-ray diffraction. As determined by GC and ¹H NMR spectroscopy, isosteviol selectively includes toluene from the equimolar benzene-toluene mixture, o-xylene from a commercial mixture of xylenes, o-and m-nitroanilins from their mixture with p-nitroanilin, and also styrene from styrene-ethylbenzene and styrene-isopropylbenzene mixtures thus yielding crystalline inclusion complexes.     

Synthesis of 6,8-substituted 4-(hydroxyphenylamino)- and 4-(aminophenylamino)-2-methylquinolines

A procedure has been developed for the synthesis of 4-(hydroxyphenylamino)- and 4-(aminophenylamino)-2-methylquinolines having a substituent in the 6(8)-position of the quinoline ring from the corresponding 4-chloro-2-methylquinolines and o-, m-, and p-aminophenols and o-, m-, and p-phenylenediamines.     

DMT [(−)-(2<Emphasis Type="Italic">R</Emphasis>,3<Emphasis Type="Italic">R</Emphasis>)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol], a highly efficient host compound for nitroaromatic guests: selectivity,X-ray and thermal analyses

In this work, we reveal that the compound (?)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) is a highly efficient host material for nitroaromatics o-nitrotoluene (o-NT), m-nitrotoluene (m-NT), p-nitrotoluene (p-NT) and nitrobenzene (NB). Each of these guests was included with a 2:1 host:guest ratio. The host displayed selectivity for p-NT and NB when these guests were mixed in equimolar proportions with any one of the other guest solvents, and the host recrystallized from this binary mixture. A selectivity order for the host in these conditions was thus noted to be NB?≈?p-NT?>?o-NT?>?m-NT. Furthermore, guests were also mixed in non-equimolar proportions and the host behaviour analysed, the results of which were in accordance with observations from the equimolar studies. Additionally, an equimolar quaternary experiment of all four guests provided a somewhat adjusted host selectivity order [p-NT (39.9%)?>?NB (30.2%)?>?m-NT (17.1%)?>?o-NT (12.8%)]. Single crystal diffraction analyses of all four complexes showed the crystals to share the same host packing, and comparable host–guest interactions were observed in each. However, thermal analyses, both DSC and TG, showed that the preferred guests p-NT and NB formed complexes with increased relative thermal stabilities, and this observation correlated with the selective behaviour of the host in competition experiments.     

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.     

Theoretical study on the fluorination of benzene with N-Fluoropyridinium salts in acetonitrile solution

The prominent roles of organofluorine compounds in various fields have aroused considerable interest in the development of new methods for carbon-fluorine bond formation. Electrophilic fluorination receives much attention. Density functional theory (DFT) was used to theoretically explore the fluorination activity of 12 N-Fluoropyridinium salts on the substrate of benzene in acetonitrile solution. Geometry optimizations and frequency calculations of the reactants, transition states, and products were performed at B3LYP/6-311G(d,p) level for the 12 fluorination reaction channels. Based on the optimized structure, all the stationary points have been corrected by the single point energy at a high-level of M06-2x/6-311++G (d,p). Four substituents were considered in this paper, they are nitro-, cyano-, chloro-, methoxy-, respectively. Three substituted sites (ortho-, meso-, para-) were also concluded. Based on the obtained potential energy surfaces information and analysis of substituent effect, the fluorination reaction channel of oNO₂NFpyr is most efficient due to the lowest reaction energy barrier; therefore, oNO₂NFpyr is a promising optimum fluorinating reagent among the studied 12 N-Fluoropyridinium salts.     

Reduction of nitrophenols in an electrocatalytic system

Results of research into hydrogenation of o- and p-nitrophenols in an electrocatalytic system on a cathode activated with d- and s-metal catalysts are presented. The optimal conditions for o-aminophenol formation on Raney nickel were identified by the probability-determined method for the experimental design.     

Reductive acylamination of pyridine <Emphasis Type="Italic">N</Emphasis>-oxide with ethylenediamine and phenylenediamines

Reactions of pyridine N-oxide with ethylenediamine and o- and p-phenylenediamines in the presence of p-toluenesulfonyl chloride in alkaline medium lead to the formation of the corresponding N,N′-bis-(p-tolylsulfonyl)-N,N′-bis(pyridin-2-yl)diamines as a result of reductive acylamination.     

Design of postmetallocene Schiff base-like catalytic systems for polymerization of olefins: XII. Synthesis of tetradentate bis-salicylaldehyde imine ligands

Reactions of salicylaldehyde, 3-tert-butylsalicylaldehyde, and 3,5-di-tert-butylsalicylaldehyde with 1,4-diaminobutane, 1,6-diaminohexane, 4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′,5,5′-tetramethyldiphenylmethane, 4,4′-diamino-5,5′-dicyclopentyl-3,3′-dimethyldiphenylmethane, 4,4′-diamino-5,5′-dicyclohexyl-3,3′-dimethyldiphenylmethane, bis(4-aminophenyl) sulfone, o,o′- and p,p′-diaminodiphenyl ethers, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4″-diamino-p-terphenyl gave a series of the corresponding Schiff bases which can be used as tetradentate ligands for the synthesis of titanium and zirconium complexes.     

3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2-benzoquinone in the synthesis of quinolino[4,5-<Emphasis Type="Italic">bc</Emphasis>][1,5]benzoxazepines,aminophenols, and phenoxazines

Reaction of 3,5-di-tert-butyl-1,2-benzoquinone with 5-amino-4-chloroquinolines gave derivatives of a new fused heterocyclic system, substituted quinolino[4,5-bc][1,5]benzoxazepines. The molecular structure of 9,11-di-tert-butyl-2,4,6-trimethyl-7H-quinolino[4,5-bc][1,5]benzoxazepine was determined by X-ray analysis. 3,5-Di-tert-butyl-1,2-benzoquinone reacted with o-nitro-, o-acyl-, and o-methoxycarbonylanilines and some amino-substituted nitrogen-containing heterocycles to form the corresponding sterically hindered N-aryl-(hetaryl)-o-aminophenols. Di-tert-butyl-substituted phenoxazines were obtained as a result of thermal cyclization of intermediately formed quinone imines.     

Effect of donor and acceptor properties of solvents on the kinetics of photoreduction of sterically hindered <Emphasis Type="Italic">о</Emphasis>-benzoquinones

Effect of the solvent nature on the kinetics of photoreduction of 3,6-di-tert-butyl-1,2-benzoquinone and its six derivatives in the presence of N,N-dimethylaniline and 4-(N,N-dimethylamino)benzaldehyde has been investigated. It has been found that for the о-quinone—amine pair, for which the free energy change of electron transfer is ΔG_e > +0.11 eV, the rate constant of о-quinone photoreduction k_H decreases proportionally to the increase in the acceptor number of the solvent. For the о-quinone—amine pair with ΔG_e < +0.11 eV, the k_H value decreases proportionally to the increase in the donor number of the solvent. It has been established that the enhancement of the electron-acceptor properties of the solvent leads to the emergence of kinetic isotope effect for the reactant pairs of 3,6-di-tert-butyl-1,2-benzoquinone and 4,5-dimethoxy-3,6-di-tert-butyl-1,2-benzoquinone with N,N-di-methylaniline (ΔG_e = +0.11 and +0.22 eV, respectively).     

Formation of solvate structures by the <Emphasis Type="Italic">ortho</Emphasis>-, <Emphasis Type="Italic">meta</Emphasis>-, and <Emphasis Type="Italic">para</Emphasis>-isomers of hydroxybenzoic acid in supercritical fluid

The solvate structures formed by the ortho-, meta-, and para-isomers of hydroxybenzoic acid (o-HBA, m-HBA, and p-HBA) with a polar co-solvent (methanol at a concentration of 0.030 and 0.035 mole fractions) in supercritical carbon dioxide at a constant density of 0.7 g/cm³ and temperatures of 318 and 328 K have been studied by the classic molecular dynamics. It has been determined that a stable hydrogen-bonded complex with the co-solvent forms via the hydrogen of the carboxyl group for all isomers. The probability of this complex existence is high at all temperatures and concentrations. In the o-HBA molecule, the other functional groups are engaged in the intramolecular hydrogen bond, but not involved in interactions with methanol. It has been found that m-HBA and p-HBA can be involved in hydrogen bonds with methanol via hydroxyl hydrogen and oxygen atoms; they are characterized by the presence of one more co-solvent molecule (rarely, two molecules) in their solvation shell and intermittent formations/breakages of hydrogen bonds via other functional groups. These bonds are far less stable, and their formation is sensitive to change of temperature and co-solvent concentration. It has been concluded that the degree of selective solvation of m-HBA and p-HBA by co-solvent molecules is approximately the same, but the rate of structural rearrangements in the nearest environment of m-HBA is higher than that of p-HBA.     

Stereochemistry of seven-membered heterocycles: XLVI. Synthesis and dynamic <Superscript>13</Superscript>C NMR spectroscopy of spiro[cyclohexane-1,4′-[3,5]dioxabicyclo[5.1.0]octanes]. DFT calculations of structurally related formaldehyde and acetone acetals

Spiro[cyclohexane-1,4′-[3,5]dioxabicyclo[5.1.0]octanes] were synthesized, and their conformational behavior was studied by dynamic ¹³C NMR spectroscopy. Anancomeric displacement of conformational equilibrium toward two nonequivalent twist conformers with close energies was revealed. The relative Gibbs energies ΔG ^o and enthalpies of formation ΔH ^o of twist and chair-like conformers with endo and exo orientation of the three-membered ring of structurally related formaldehyde and acetone acetals were calculated in terms of the density functional theory at the B3LYP/6-31G(d,p) level. Like spiro-cyclohexane analogs, they were shown to have a non-chair conformation.     

Reaction of 3-carene with perfluoroalkanoic acids

The addition of perfluoroalkanoic acids to 3-carene involves opening of the cyclopropane ring at the peripheral bonds with formation of a mixture of isomeric p-menth-1-en-8-yl and m-menth-1-en-8-yl perfluoroalkanoates. The reaction rate decreases as the length of the perfluoroalkyl radical of the acid increases. Trichloroacetic acid reacted with 3-carene at a lower rate than does trifluoroacetic acid, but the products are analogous p-menth-1-en-8-yl and m-menth-1-en-8-yl trichloroacetates.     

The thermodynamic properties of the [(Me<Subscript>3</Subscript>Si)<Subscript>7</Subscript>C<Subscript>60</Subscript>]<Subscript>2</Subscript> fullerene complex

The temperature dependence of the heat capacity C _p ^o of the [(Me₃Si)₇C₆₀]₂ fullerene complex was measured for the first time using precision adiabatic vacuum calorimetry over the temperature range 6.7–340 K and high-accuracy differential scanning calorimetry at 320–635 K. For the most part, the error in the C _p ^o values was about ±0.5%. An irreversible endothermic effect caused by the splitting of the dimeric bond between fullerene fragments and the thermal decomposition of the complex was observed at 448–570 K. The thermodynamic characteristics of this transformation were calculated and analyzed. Multifractal analysis of the low-temperature (T < 50 K) heat capacity was performed, and conclusions were drawn concerning the character of the heterodynamicity of the structure. The experimental data obtained were used to calculate the standard thermodynamic functions C _p ^o (T), H ^o (T) ? H ^o (0), S ^o (T) ? S ^o (0), and G ^o (T) ? H ^o (0) over the temperature range from T → 0 to 445 K and estimate the standard entropy of formation of the compound from simple substances at 298.15 K. The standard thermodynamic properties of [(Me₃Si)₇C₆₀]₂ are compared with those of the (C₆₀)₂ dimer, the [(η⁶-Ph₂)₂Cr]⁺[C₆₀]^?? fulleride, and the initial C₆₀ fullerene.     

Fusion of 2-(furan-2-yl)thiazole to 1-methyl-1<Emphasis Type="Italic">H</Emphasis>-benzimidazole

Methylation of 5(6)-nitro-1H-benzimidazole with methyl iodide in the presence of potassium hydroxide and N-methylpyrrolidin-2-one gave a mixture of isomeric 1-methyl-5-nitro- and 1-methyl-6-nitro-1H-benzimidazoles which were reduced with tin in concentrated aqueous HCl on heating. The resulting amines reacted with furan-2-carbonyl chloride in N-methylpyrrolidin-2-one to give furan-2-carboxamides which were treated with excess P₂S₅ in pyridine. Oxidation of isomeric furan-2-carbothioamides with K₃[Fe(CN)₆] in alkaline medium afforded a mixture of intramolecular cyclization products, 2-(furan-2-yl)-6-methyl-6H-imidazo[4,5-g][1,3]benzothiazole and 2-(furan-2-yl)-8-methyl-8H-imidazo[4,5-g][1,3]benzothiazole which were separated by column chromatography and identified.