The directing effect of annelated rings in aromatic systems—XI : Bromination of bicyclic phenols with heterocyclic annelated rings

Bicyclic phenols of type 1 with annelated rings containing a N or an O heteroatom (X = N or O) as well as the ring opened analogs have been brominated and the product distribution determined. The results indicate that while most annelated rings have a directing effect to the ar-β position of the molecule, a 6-membered annelated ring is an exception and it facilitates substitution in the ar-α position.     

Nature of the excited states of dialkylamino derivatives of aromatic and heteroaromatic compounds with an annelated oxazole ring

On the basis of analysis of the electron density redistribution upon excitation, drawing on charge transfer numbers, we have considered the nature of the electronic transitions in the absorption spectra of analogs of 2,5-diphenyloxazole, in which the carbon atom at position 4 of the oxazole ring is bonded to the ortho position of the 5-phenyl fragment of the vinylene, azomethine, amide, and ester groups. We have shown that the differences in the electronic transitions of the basal molecule and the studied structural analogs are determined by the electron-donor effect of the bridging group and the degree of its conjugation with the extended -electron system of the original molecule. The dialkylamino derivatives of the studied compounds, on the other hand, display a high degree of similarity in the electronic structure of the excited states, and the characteristics of their long-wavelength transitions, such as in the case of substitution of the 2-phenyl fragment, do not depend on the nature of the bridging group of atoms. We give a theoretical explanation of the experimentally observed increase in the intensity of the long-wavelength transitions and the efficiency of luminescence upon introduction of dialkylamino groups into the 2- and 5-phenyl fragments.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 6, pp. 644–650, November–December, 1990.     

Formation of derivatives of n-hydroxyindoles,annelated with furazan and furoxan rings

Upon reaction of 4-oxo-5-hydroxyimino-4,5,6,7-tetrahydrobenzofurazan and tetrahydrobenzofuroxan with acetylacetone, 8-acetyl-6-hydroxy-7-methylpyrrolo[2,3-e]benzofurazan and -benzofurazan-3-oxide are formed; and upon reaction with acetoacetate, 8-ethoxycarbonyl-6-hydroxy-7-methylpyrrolo[2,3-e]benzofurazan and -benzofurazan-3-oxide are formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1676–1678, December, 1993.     

A new synthesis of n-acyl aromatic α-amino acids—amidoalkylation of aromatic and heterocyclic compounds with glyoxylic acid derivatives

The synthesis of N-acyl derivatives of aromatic α-amino acids 5 by the amidoalkylations of aromatic and heterocyclic compounds with glyoxylic acid amide adducts is described.     

Synthesis and study of heterocyclic derivatives with biological properties

Certain derivatives of benzotriazole containing the cytotoxic bis(ß-chloroethyl)amino group are synthesized. They are 1-p-[bis(ß-choroethyl)amino]tolylbenzotriazole and (benzotriazolyl-4)-amidoacetylsarcolysine.For Part VI see [10].     

Spectral-luminescent properties of natural coumarin derivatives and their use for group identification

Natural hydroxycoumarins and their derivatives possess an intensive fluorescence depending on the type and position of substituents. From the wavelengths of the fluorescence maxima and the sizes of the Stokes shifts it is possible to identify the groups to which coumarins belong — hydroxycoumarins, furocoumarins, and angular dihydrofuro- and dihydropyranocoumarins.     

Spectral-luminescent properties of natural coumarin derivatives and their use for group identification

Natural hydroxycoumarins and their derivatives possess an intensive fluorescence depending on the type and position of substituents. From the wavelengths of the fluorescence maxima and the sizes of the Stokes shifts it is possible to identify the groups to which coumarins belong — hydroxycoumarins, furocoumarins, and angular dihydrofuro- and dihydropyranocoumarins.All-Union Scientific-Research Institute of Drug Chemistry and Technology, Khar'kov. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 766–769, November–December, 1985.     

Hydroxide-catalyzed synthesis of heterocyclic aromatic amine derivatives from nitriles

A generalized method for synthesizing a wide variety of heterocyclic aromatic amine derivatives from nitriles by use of hydroxide catalysts is presented. Nitrile dimers (3-aminocrotononitrile and dicyandiamide) and a dimer analog (anthranilonitrile) react with monomeric nitriles in the presence of hydroxide to form respectively, aminopyrimidines, diaminotriazines and aminoquinazolines.     

Convenient magnesiation of aromatic and heterocyclic rings bearing a hydroxy group in presence of LiCl

The reaction of various iodophenols with MeMgCl in presence of LiCl followed by the addition of i-PrMgCl provides the corresponding magnesiated magnesium phenolates as THF soluble reagents; this approach can be extended to heterocyclic compounds bearing a hydroxy group like pyridines and quinolines.     

Synthesis of heterocyclic derivatives of dihydroquinopimaric acid

Heterocyclic derivatives of dihydroquinopimaric acid were synthesized, in which indole, pyrazole, or pyrimidine ring is fused to the E ring of the acid.     

Determination of thiocyanate with aromatic halosulphonamides in acid and alkaline media

Ten organic aromatic halosulphonamides, both mono and dihalo compounds, ranging from chlorosulphonamides to iodosulphonamides, have been prepared and characterized by their infrared and NMR spectra and successfully used for determining thiocyanate in its metal salts and complexes. The proposed procedures are simple, rapid and reproducible, with an error of about +/-0.8%. These procedures are also useful for computing the number of thiocyanate ligands present in the complexes. Comparison of the present results with those from the argentometric method shows excellent agreement. The oxidation involves an 8-electron change per thiocyanate ion with the chloro and bromosulphonamides and a 6-electron change with iodosulphonamides.     

Polymethine dyes which are derivatives of heterocyclic bases containing condensed thiophene rings

Some new polymethine dyes of the cyanine and merocyanine series, containing thieno[2, 3-b]thieno[2, 3-b]pyridine-4 and thieno[3, 2-b]-thieno[2, 3-b]-pyridine-8 groups are synthesized. Replacement of the vinylene group by a sulfur atom in the condensed benzene rings of the 5, 6-benzoquinoline-4 group in dyes which are derivatives of this base, results in a marked hypsochromic shift of the absorption maximum of the corresponding dyes.For Part IV see [8].     

Ureidoalkylations and oxyalkylation of aromatic compounds with glyoxylic acid derivatives

The ureidoalkylation of benzene, toluene, xylene, anisole, phenol, acetanilide and chlorobenzene with N,N-dimethylurea-glyoxylic acid adducts 1 and 6 gives substituted N,N-dimethylcarbamoyl-DL-phenylglycine. The oxyalkylation of benzene with glyoxylic acid, methyl glyoxylate and methyl dimethoxyacetate is also described (see Table 1).     

A novel method for sulfonation of aromatic rings with silica sulfuric acid

Direct and chemoselective sulfonation of aromatic compounds with silica sulfuric acid in 1,2-dichloeoethane or under solvent-free conditions.     

Spectral-luminescent properties of actinides in elpasolite structure

Absorption, luminescence and self-luminescence spectra of transuranium elements (Np³⁺, Am³⁺, Cm³⁺) doped into Cs₂NaLnCl₆ (Ln=La, Lu) crystals are presented. In the case of Am³⁺ an attempt has been made to investigate luminescence excitation mechanisms. One of the luminescence features characteristic of the Am- and Cm-doped elpasolites appears to be dominante green glow. The octahedral ligand-field calculations were performed by the pair interaction method. The main properties of f-f transition spectra in crystals of elpasolite type are discussed.