An optimized protocol for the multigram synthesis of 3-(trifluoromethyl)bicyclo[1.1.1]pent-1-ylglycine (CF3-Bpg)

An optimized procedure for the multigram synthesis of 3-(trifluoromethyl)bicyclo[1.1.1]pent-1-ylglycine (CF₃-Bpg) has been developed. The overall yield of the synthesis for the optimized up-scaling was increased from 35% to 53%. Moreover, conditions for separating the key isomeric aminonitriles 7 and 8 by crystallization were found, which greatly facilitated the isolation of 8 on a multigram scale. Following this optimized protocol, 100 g of optically pure CF₃-Bpg have been synthesized.     

Effect of oxygen pressure on phase equilibria in the Eu-Mn-O system

Phase equilibria in the Eu-Mn-O system are studied using the static method in combination with X-ray phase analysis. Compound EuMnO₃ was studied by means of DSC and high-temperature roentgenography. The transformation of the orbitally ordered O′ phase to the orbitally disordered O phase was confirmed for the EuMnO₃ compound. Thermodynamic characteristics of the formation of EuMn₂O₅ and EuMnO₃ compound from their elements were calculated.     

Simulating the proton transfer reaction in the phosphoric acid-N,N-dimethylformamide system by means of the AM1 semiempirical method

Using the AM1 semiempirical method, we calculate the energy profile of the proton transfer reaction during the formation of a hydrogen bond between molecules of phosphoric acid (H₃PO₄) and N,N-dimethylformamide (DMFA) in both gas and liquid phases. The energy barriers of the reaction transition are estimated. The changes in the geometric parameters of hydrogen bonds and the intermolecular interaction energy of H₃PO₄-DMFA and (H₃PO₄)₂-DMFA complexes during the transition from the gas phase into the solution are analyzed.     

The Stone--Weierstrass Theorem and Spaces of Measures

Results concerning the Stone--Weierstrass theorems for completely regular spaces are obtained.     

Synthesis of crown-containing 2-styrylbenzothiazoles. Effect of alkali metal cations on the condensation of crown-ether benzaldehydes with 2-methylbenzothiazole

Methods for the synthesis of unknown 2-styrylbenzothiazoles containing crown ether moieties with different combinations of O, S, and N-heteroatoms based on the Wittig reaction or condensation of 2-methylbenzothiazole with crown-ether benzaldehydes in the presence of strong bases or acids are proposed. The condensation in the presence of bases is accompanied by complex formation with participation of the crown ether moiety of the benzaldehyde. The complex formation has a pronounced influence on the yield of the target product and the pattern of condensation of 2-methylbenzothiazole with crown-ether benzaldehydes.     

Synthesis and structures of azine-based crown-containing hetarylphenylethenes

Condensation of methyl-substituted six-membered heteroaromatics containing one or two nitrogen atoms with aldehyde derived from benzo-15-crown-5 ether in DMF in the presence of Bu^tOK afforded 15-crown-5-containing hetarylphenylethenes. According to the results of NMR spectroscopy, these compounds exist as mixtures of syn and anti conformers in solution (MeCN-d₃). The structures of two compounds were established by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1650–1659, July, 2005.     

Influence of Allotropic Forms of Carbon on Formation and Cross-Linking of Heat-Resistant Polymer Binders

The thermochemical reactions of polyimide binder with various allotropic forms of carbon, fullerene C₆₀ and ultradispersed artificial diamonds, were studied by thermal and spectral analyses.