Grigorii G. Alexandrov

A Domino Reaction of α,β-Acetylenic γ-Hydroxy Nitriles with Arenecarboxylic Acids: An Unexpected Facile Shortcut to 4-Cyano-3(2H)-furanones

An unexpected facile domino reaction of alpha,beta-acetylenic gamma-hydroxy nitriles with arenecarboxylic acids (Et(3)N, MeCN, 20-25 degrees C, 48 h) affords 4-cyano-3(2H)-furanones in 67-86% yield. The reaction is triggered by the addition of an arenecarboxylic acid to a triple bond, followed by the domino reaction sequence: intramolecular transesterification-enol formation and Claisen condensation of the ketoacetonitrile tautomer with ester functional group.

Z/E (C=C)-isomerization and fluorescence modulation of imines of 7-N,N-dialkylamino-4-hydroxy-3-formylcoumarins in organic solvents

Abstract Imines of 7-dialkylamino-3-formyl-4-hydroxycoumarins have been found to exist in Z-ketoenamine form in crystal state and undergo Z/E-isomerization around C=C bond in organic solvents at room temperature. Activation energies of isomerization have been measured experimentally and calculated by the DFT B3LYP method. Transition of ketoenamine form of p-nitrophenylimines into (hydroxy)imine form at low concentration (10-5 m) in polar solvents is accompanied by strong increase in fluorescence.

New Electroconducting Radical Cation Salts Based on BEDT-TTF with 8,8’-Dibromo Cobalt Bis(Dicarbollide) Anion

New molecular conductors on the base of 8,8’-dibromo cobalt bis(dicarbollide) anion, (BEDT-TTF)2[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (1), and (BEDT-TTF)[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (2) were synthesized and their crystal structures and electrical conductivities were determined. Both radical cation salts prepared were found to be semiconductors. The introduction of two bromine atoms in the cobalt bis(dicarbollide) anion produces a strong effect on crystal structure and electrical conductivity of the prepared materials.

Tautomeric Forms of 3-Formyl- 4-Hydroxycoumarin Arylhydrazones

Tautomeric forms of 3-formyl-4-hydroxycoumarin arylhydrazones were studied by 1H and 13C NMR spectroscopy, as well as X-ray structural analysis. These compounds were shown to exist primarily in the 4-hydroxycoumarin form both in DMSO solution, as well as in gas phase; the chroman-2,4-dione form was a minor component. According to X-ray structural analysis data, solid 3-formyl-4-hydroxycoumarin phenylhydrazone exists in the 4-hydroxycoumarin form.

Chemical assembly of the heteronuclear pivalate complex with the LiI and FeIII ions

The heteronuclear complex [Fe4Li2(O)2(Piv)10(H2O)2] (1, Piv is the pivalic acid anion) was obtained by refluxing FeIII pivalates with LiI pivalates in toluene and isolated as the 1•PhCH3 solvate with a toluene molecule. According to X-ray diffraction data, complex 1 contains the {Fe4Li2O2} core. The Mössbauer spectroscopy data indicate that the core comprises para magnetic FeIII ions in the high-spin state located in the symmetric octahedral environment of oxygen atoms. Thermolysis of 1 studied by simultaneous thermal analysis demonstrated thermal stability of the complex up to 225 °С. The main end product of thermolysis at 600 °С is the mixed oxide LiFe5O8.