Synthesis of derivatives of <Emphasis Type="Italic">o</Emphasis>-aminoacetophenone and <Emphasis Type="Italic">o</Emphasis>-aminobenzyl alcohol

Oxidation of 2′-hydroxy-8-methylspiro[4H-benz-1,3-oxazin-2-one-6,1′-cyclopentane] or N-mesyl-2-(cyclopent-1-en-1-yl)-6-methylaniline provided the corresponding ketones. The rearrangement of these ketones oximes under treatment with thionyl chloride gave rise to nitriles of 5-(2-amino-3-methylphenyl)-5-oxopentanoic or 5-(2-methanesulfamido-3-methylphenyl)-5-hydroxypentanoic acids. By heating 5-(2-acetylamido-3-methylphenyl)-5-oxopentanoic acid with LiH in THF3-(2,8-dimethylquinol-4-on-3-yl)propanoic acid was obtained.     

Synthesis and structure of bis(1,2-diaminoethane) copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-hydroxybenzoate) monohydrate and <Emphasis Type="Italic">trans</Emphasis>-diaquabis(1,2-diaminoethane)copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-aminobenzoate)

X-ray structural analysis has been performed for two complex compounds: Cu(en)₂(o-HB)₂H₂O (I) (a = 16.873(4) Å, b = 8.713(2) Å, c = 14.803(3) Å, β = 91.15(2)°, V = 2175.8(8) ų, C2/c, Z = 4, R(F) = 0.0263, 1516 reflections with I > 3σ (I)) and [Cu(en)₂(OH₂)₂]²⁺(o-AB^?)₂ (II) (a = 7.488(5) Å, b = 22.122(8) Å, c = 7.856(5) Å, β = 118.77(2)°, V = 1140.7(11) ų, P2₁/n, Z = 2, R(F) = 0.0432, 1684 reflections with I > 3σ(I)) synthesized under identical conditions (en is ethylenediamine, o-HB is o-hydroxybenzoate, and o-AB is o-aminobenzoate). Although the compounds were assumed to have similar structures and the Cu-Lig bond lengths and the cis and trans angles are acceptable for an octahedral structure, the geometric parameters of o-HB suggest that the copper atom has a plane square environment.     

Zinc(II) and cadmium(II) complexes with <Emphasis Type="Italic">o</Emphasis>-hydroxybenzoic acid or <Emphasis Type="Italic">o</Emphasis>-aminobenzoic acid and 2-methylimidazole

Mixed complexes of the type: Zn(Hsal)₂(2-MeHim)₂, Zn(Han)₂(2-MeHim)₂, Cd(Hsal)₂(2-MeHim)₂, Cd(Han)₂(2-MeHim)₂, where Hsal=OHC₆H₄COO⁻, Han=NH₂C₆H₄COO⁻, 2-MeHim=2-methylimidazol) have been synthesized and characterized by IR spectroscopic and X-ray diffraction studies. Single-crystal X-ray structure of Cd(Hsal)₂(2-MeHim)₂ has been obtained. Thermal behaviour of the compounds was investigated by thermal analysis (TG, DTG, DTA). A coupled TG-MS system was used to analyse the principal volatile products of complexes. Thermal decomposition pathways have been postulated.     

New tin(<Emphasis Type="SmallCaps">iv</Emphasis>) <Emphasis Type="Italic">o</Emphasis>-iminosemiquinone complexes

New tin(iv) mono- and bis-o-iminosemiquinone complexes were obtained by the exchange reaction of radical anion lithium salt of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-imino-benzoquinone with tin(iv) organochlorides. The compounds synthesized were characterized by EPR spectroscopy and X-ray diffraction analysis. Substituents on the tin atom were found to affect stability of paramagnetic metal derivatives formed.     

Synthesis of <Emphasis Type="Italic">o</Emphasis>(<Emphasis Type="Italic">m</Emphasis>)-carborane-containing azomethines

A method of preparative synthesis of o(m)-carborane-containing azomethines via the condensation of o(m)-carboranyl-C-methylene-4-formylbenzoates with aliphatic, cycloaliphatic, and aromatic amines was developed.     

<Emphasis Type="Italic">bis</Emphasis>(<Emphasis Type="Italic">N,N</Emphasis>-diethylnicotinamide) <Emphasis Type="Italic">p</Emphasis>-chlorobenzoate complexes of Ni(II), Zn(II) and Cd(II)

Three novel mixed ligand complexes of Ni(II), Zn(II) and Cd(II) with p-chlorobenzote and N,N-diethylnicotinamide were synthesised and characterized on the basis of elemental analysis, FTIR spectroscopic analysis, solid state UV-Vis spectrometric and magnetic susceptibility data. The thermal behavior of the complexes was studied by simultaneous TG-DTA methods in static air atmosphere and the mass spectra data were recorded. According to microanalytical results, formulas of complexes are C₃₄H₄₀N₄O₈ClNi, C₃₄H₄₀N₄O₈ClZn and C₃₄H₄₄N₄O₁₀ClCd. The complexes contain two moles of coordination waters, two moles p-chlorobenzoate and two mole N,N-diethylnicotinamide (dena) ligands per formula unit. In these complexes, the p-chlorobenzoate and N,N-diethylnicotinamide behave as monodentate ligand through acidic oxygen and nitrogen of pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be as metal oxides.     

Molecular structure of <Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">o</Emphasis>-and <Emphasis Type="Italic">p</Emphasis>-hydroxybenzyl)cytisine

The molecular structures of N-(o-and p-hydroxybenzyl)cytisine were investigated by NMR spectroscopy, x-ray structure analysis, and molecular modeling. It was found that NMR resonances of the OH and aromatic protons in N-(o-hydroxybenzyl)cytisine were doubled because of the presence of two conformers in solution. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 2008.     

Oxidation kinetics of Zn-5,15 bis(<Emphasis Type="Italic">ortho</Emphasis>-methoxyphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin with organic peroxides in <Emphasis Type="Italic">o</Emphasis>-xylene

With the purpose of further investigation of the effect of the steric strain of the porphyrin macroring in metal porphyrins on their redox properties, kinetics of oxidation of Zn-5,15 bis(ortho-methoxyphenyl)-2,3,7,8,12,13.17,18-octamethylporphyrin with organic peroxides in o-xylene at 295°C were studied spectrophotometrically to show that this process leads to complete destruction of the complex. Kinetic characteristics (k _ef, k _v) of the process were evaluated. The structure of the zinc porphyrin and its oxidation intermediates were obtained by quantum-chemical calculations. Steris strains in the metal prophyrin macroring were revealed and shown to enhance in the course of the reaction. An effect of the degree of deformational strain on the oxidation rate was noted.     

Electrochemical transformations of catecholate and <Emphasis Type="Italic">o</Emphasis>-amidophenolate complexes with triphenylantimony(V)

The electrochemical properties of catecholate and o-amidophenolate complexes with triphenylantimony(V) with various substituents in the aromatic ring were examined. Introduction of electron-donating groups into the catecholate ligand or replacement of an O atom (in catecholate) by a N atom (o-amidophenolate) stabilizes the monocationic forms of the complexes obtained by one-electron oxidation. Complexes with electron-withdrawing substituents undergo irreversible two-electron oxidation resulting in the elimination of o-quinone. Complexes containing electron-withdrawing ligands do not form o-semiquinones and are inert to atmospheric oxygen. According to electrochemical data, oxygen can be bound reversibly by catecholate complexes containing the electron-donating methoxy groups in the 3,6-di-tert-butylcatecholate ligand and o-amidophenolate derivatives with half-wave oxidation potentials lower than or equal to 0.70 V (vs. Ag/AgCl), which form relatively stable cationic complexes upon the oxidation.     

Conformational Polymorphism in Racemic 2,4-Di-<Emphasis Type="Italic">o</Emphasis>-Benzoyl-6-<Emphasis Type="Italic">o</Emphasis>-Tosyl <Emphasis Type="Italic">myo</Emphasis>-Inositol 1,3,5-Orthoacetate

The title compound, C₂₉H₂₆O₁₀S, yields two conformational polymorphs concomitantly from dichloromethane-methanol mixture; the major polymorph grows as plates (Form I, monoclinic, P2₁/n) and the minor polymorph grows as needles (Form II, triclinic, P-1). The two forms differ mainly in orientation of the tosyl group. In Form I, sulfonyl oxygen of the tosyl group makes intermolecular C −H…O interactions, whereas the same group in Form II is involved in an intramolecular short dipolar S=O…C=O (sulfonyl-carbonyl) contact. The molecular organization and the influence of various weak non-covalent interactions that stabilize these conformers in the crystal lattices are discussed.     

Versatility and reactivity of salicylaldehyde <Emphasis Type="Italic">S</Emphasis>-methylisothiosemicarbazone in palladium(II) complexes

New palladium(II) complexes, [Pd(HL)Cl] · H₂O (I) and {K[Pd(L¹)(NO₂)] · H₂O}₂, with S-methylisothiosemicarbazone of salicylaldehyde (H₂L) and its derivative (H₂L¹) were synthesized. X-ray diffraction analysis demonstrated the ambident nature of S-alkylated thiosemicarbazone, which is attached to palladium(II) through O, N, and S donor atoms in I and through O, N, and N atoms in II. This is the first known case of metal coordination of the alkylated sulfur atom of a thiosemicarbazide moiety of the ligand. A mechanism of nitrosation of the terminal amide nitrogen atom of the H₂L¹ ligand during complexation was proposed.     

Photolysis of <Emphasis Type="Italic">o</Emphasis>-iodo- and <Emphasis Type="Italic">o</Emphasis>-bromophenols in aqueous solution of sodium sulfite and organic solvents

The photochemical reaction of o-iodo- and o-bromophenol in an aqueous sodium sulfite solution proceeds via both nonchain and chain mechanisms. The formation of the intermediate product, aromatic radical anion, was observed. The quantum yield of the photochemical reaction of o-iodophenol increases, when the electron donor diphenylamine is irradiated. In the photolysis of o-halophenols in organic solvents, free iodine is evolved in addition to aromatic products. The products of the photolysis of o-iodophenol in ethanol and carbon tetrachloride were identified by gas chromatography-mass spectrometry. These are phenol in the case of ethanol and a mixture of o-chlorophenol and hydroxychloro-substituted biphenyls in the case of carbon tetrachloride. The quantum yields were determined for all photochemical reactions studied.     

Binuclear copper(II) complexes with acyldihydrazones of <Emphasis Type="Italic">N</Emphasis>-benzenesulfonyl-<Emphasis Type="Italic">L</Emphasis>-aspartic acid

The structure and the EPR spectra of copper(II) coordination compounds with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid and salicylaldehyde (2-hydroxyacetophenone) were described. The compounds were studied by chemical and thermal analyses, IR spectroscopy, and EPR. The molecular and crystal structures of copper(II) complexes with N-benzenesulfonyl-L-aspartic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹ · 2Py] · 1.5 H₂O was determined by X-ray diffraction. The crystals are triclinic: a = 10.4714(4) Å, b = 12.9702(5) Å, c = 14.6187(9) Å, α = 104.763(2)°, β = 93.082(2)°, γ = 111.4240(10)°, space group P \(\bar 1\), Z = 2. The binuclear complexes containing copper cations whose coordination polyhedra are connected by an aliphatic spacer (Cu...Cu, 8.669 Å) are additionally linked by phenoxy bridges (Cu...Cu, 3.398 Å). The EPR spectra of these compounds in solutions exhibit an isotropic signal of seven HFS lines due to two equivalent copper ions with the spin Hamiltonian parameters g = 2.115?2.120, a _Cu = (35.5?38.0) × 10^?4 cm^?1, which is indicative of weak exchange interactions between the paramagnetic sites.     

Copper(II), nickel(II), and zinc(II) complexes with <Emphasis Type="Italic">o</Emphasis>-tozylaminobenzaldehyde 4,6-dimethylpyrimidyl hydrazone

o-Tosylaminobenzaldehyde dimethylpyrimidyl hydrazone and its copper(II), nickel(II), and zinc(II) complexesare synthesized and studied. According to the X-ray diffraction data, the zinc(II) complex has the structure of a tetragonal pyramid with the N₃O donor ligand environment. According to EPR and magnetochemistry data, the copper(II) complex has a similar structure of the chelate core. In the nickel(II) complex, the solvent molecule completes the coordination core to an octahedron.     

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.     

Reaction 5-(Arylmethylidene)pyrimidine-2,4,6(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>,5<Emphasis Type="Italic">H</Emphasis>)-triones with L-Proline and Aldehydes

Boiling in toluene of 5-(arylmethylidene)pyrimidine-2,4,6(1H,3H,5H)-triones with L-proline and aldehyde led to the formation of previously unknown substituted 1′-arylhexahydro-1H-spiro[pyrimidine-5,2′-pyrrolysine]-2,4,6(1H,3Н,5Н)-triones.     

<Emphasis Type="Italic">Z</Emphasis>-and <Emphasis Type="Italic">E</Emphasis>-conformers of <Emphasis Type="Italic">N</Emphasis>-chloroacetylcytisine

N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated.     

Curing reaction of <Emphasis Type="Italic">o</Emphasis>-cresol-formaldehyde epoxy/LC epoxy(<Emphasis Type="Italic">p</Emphasis>-PEPB)/anhydride(MeTHPA)

The curing kinetics of a bi-component system about o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 3-methyl-tetrahydrophthalic anhydride (MeTHPA) as a curing agent, were studied by non-isothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy E _a and the conversion α was obtained by the isoconversional method of Ozawa. The reaction molecular mechanism was proposed. The results show that the values of E _a in the initial stage are higher than other time, and E _a tend to decrease slightly with the reaction processing. There is a phase separation in the cure process with LC phase formation. These curing reactions can be described by the Šesták–Berggren (S–B) equation, the kinetic equation of cure reaction as follows: \frac\textda\textdt = Aexp( - \fracE_\texta RT )a^m ( 1 - a )ⁿ {\frac{{{\text{d}}\alpha }}{{{\text{d}}t}}} = A\exp \left( { - {\frac{{E_{\text{a}} }}{RT}}} \right)\alpha^{m} \left( {1 - a} \right)^{n} .     

Sonogashira reaction catalyzed by palladium isocyanide complex modified <Emphasis Type="Italic">in situ</Emphasis>

Palladium isocyanide complex modified in situ by addition of benzohydrazide as nucleophile was shown to catalyze Sonogashira reactions of phenylacetylene with iodobenzenes in refluxing ethanol in the presence of potassium carbonate. The reactions were complete in 2 h, and neither preliminary degassing nor protection from atmospheric moisture and oxygen was necessary. The yields of the cross-coupling products, unsymmetrical diarylacetylenes were only slightly lower than those obtained with the preliminarily prepared catalyst. The proposed procedure was used to synthesize a series of diarylacetylenes containing both electrondonating and electron-withdrawing substituents in the benzene rings.     

<Emphasis Type="Italic">N</Emphasis>-aryl-<Emphasis Type="Italic">o</Emphasis>-iminobenzoquinones as novel regulators of radical polymerization

The effect of a number of quinoid compounds on methyl methacrylate polymerization initiated by azo-bis(isobutyronitrile) has been studied. It has been revealed that N-aryl-o-iminobenzoquinones, in contrast to o-benzoquinones, can provide radical polymerization of methyl methacrylate in controllable mode. The efficiency of the compounds as chain growth regulators has been found to depend on their composition and reaction conditions. It has been established that 4,6-di-tert-butyl-N-(2,6-diethylphenyl)-o-iminobenzoquinone and 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone under radical initiation conditions provide the synthesis of poly(methyl methacrylate) with wide-range molecular weight, retaining polydispersity indices about ~1.4–1.8 up to deep conversions.