Phosphorylation of 3-hydroxy- and 5,7-dihydroxyflavones with hexaethylphosphorous triamide

The reactions of 3-hydroxy- and 5,7-dihydroxyflavones with hexaethylphosphorous triamide proceed according to a classical scheme, but the reaction of 5,7-dihydroxyflavone occurs regioselectively. Dismutation of phosphites, which has been studied earlier only for the simplest aryl systems, is extended to flavonoids.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2698–2702, December, 2004.     

Interwell excitons in GaAs superlattices

The formation of spatially indirect excitons in superlattices with narrow minibands is investigated experimentally. The interwell exciton is similar to the first Wannier–Stark localized exciton of an electrically biased superlattice. However, in the present case the localization is mediated by the Coulomb interaction of the electron and the hole without external fields.     

Synthesis of zwitterionic titanocene monochloride Cp[η5-C5H4B(C6F5)3]TiCl containing tris(pentafluorophenyl)borane moiety in the η5-cyclopentadienyl ring

Russian Chemical Bulletin -     

Selective monoalkylation of phosphorus-substituted CH acids with (bromomethyl)- and 1,4-bis(bromomethyl)benzenes

C-Alkylation of phosphorus-substituted CH acids with various substituted (bromomethyl)arenes under phase transfer catalysis conditions (K₂CO₃/MeCN) proceeds with high selectivity (75—100%) as monoalkylation.     

Nature of weak inter-and intramolecular interactions in crystals 7. Stability of homochiral supramolecular organization of dications in crystals of 1,3-dialkyl-4,5-bis(3-guanidinioamino)imidazolidin-2-one salts

The geometries and peculiarities of the electronic structure of chiral 1,3-dialkyl-4,5-bis(3-guanidinioamino)imidazolidin-2-one dications (C ₂ symmetry) and their associates in salts containing chloride and nitrate anions were studied by X-ray diffraction analysis and quantum chemistry methods. Homochiral H-bonded cation chains are stable supramolecular fragments; however, their presence in the crystal structures does not provide spontaneous resolution of racemates upon crystallization. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 387–395, March, 2006.     

Reaction of 1,2-dialkyldiaziridines with ketenes as a new approach to cyclic and linear systems containing the N— C—N fragment

The reaction of 1,2-dialkyldiaziridines with ketenes proceeds through the N—N bond cleavage to form three types of structures containing the N—C—N fragment, viz., 1,3-dialkylimidazolidin-4-ones, 3,5-diacyl-3,5-diazahept-1-enes, and β-lactams. The reaction pathway depends on the reaction conditions and the structures of the starting compounds. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 997–1006, April, 2005.     

2-Phenyl-1-boraadamantane complexes. Crystal structure and use in the synthesis of cage compounds

Complexes of 2-phenyl-1-boraadamantane with trimethylamine and pyridine were studied by X-ray diffraction analysis. The 2-phenyl-1-boraadamantane adduct with tetrahydrofuran (1) was transformed to 1-hydroxy-2-phenyladamantane via a carbonylation—oxidation sequence. The intramolecular version of the organoborane reaction with organic azides was employed as a key step in the transformation of 2-phenyl-1-boraadamantane adduct (1) into 2-phenyl-1-azaadamantane (5).     

Interaction of bis(trimethylsilyl)acetylene complex of titanocene with mercury trifluoroacetate

The reaction of the bis(trimethylsilyl)acetylene complex of titanocene Cp₂Ti(Me₃SiC₂SiMe₃) with mercury trifluoroacetate (NF₃COO)₂Hg at 20 °C in a THF medium affords titanocene bis(trifluoroacetate) Cp₂Ti(OCOCF₃)₂ and metallic mercury. The structure of Cp₂Ti(OCOCF₃)₂ was established by the analytical and spectroscopic methods and X-ray diffraction analysis.     

The crystal and molecular structures of three germatrane derivatives

The molecular and crystal structure of three germatrane compounds: 1-(1-bromobicyclo[4.1.0]hept-7-yl)germatrane, l-(1-trimethylsilanyl-cyclopropyl)-germatrane and 1-(1-Methyl-1,2-dicarba-closo-dodecaboranyl)germatrane has been determined by X-ray diffraction method in order to investigate main geometrical regularities of the germatrane molecules. There were established all values of the main structural parameters above-mentioned molecules.