Search

A new one-pot method for the synthesis of earlier unknown boron-containing adamantane derivatives, spiro[adamantane-2,2′-boriranes], via the catalytic cycloboration of methyleneadamantane with BF3·THF and RBCl2·SMe2 (R is 2-norbornyl and cyclooctyl) in the presence of Cp2TiCl2 and Mg (acceptor of halide ions) was developed. The structure of spiro[adamantane-2,2′-boriranes] was elucidated using 1D (1H, 13C, 11B, and 19F) and 2D (HSQC, HMBC, COSY, and diffusion-ordered (DOSY)) NMR techniques. 1-Fluorosubstituted spiro[adamantane-2,2′-borirane] was identified as a complex with the solvent molecule (THF) according to a comparison of the experimental and calculated 11B NMR chemical shifts and the calculation data for the thermodynamic parameters of complex formation. [ABSTRACT FROM AUTHOR]

1-Fluorine-substituted spiroboracarbocycles were first synthesized by cycloboration of monoterpenes ((–)-β-pinene, (–)-camphene, and l(–)-menthol methylene derivative) with boron trifluoride (BF3·THF) in the presence of two-component catalytic system Cp2TiCl2/Mg in tetrahydrofuran. [ABSTRACT FROM AUTHOR]

The 13C NMR chemical shifts of fullerene C60 exo-derivatives were calculated using quantum chemical hybrid functionals combined with Pople, Dunning correlation-consistent, and def2-TZVP split valence basis sets taking into account the solvent effect (polarizable continuum model). A relationship between theoretical and experimental 13C NMR chemical shifts (CSs) is assessed quantitatively to select a functional/basis set combination. It is found that the CAM-B3LYP/6-31G and M06L/6-31G combinations have the best convergence with experimental data in modeling the 13С NMR CSs of sp3 fullerene carbon atoms in С60 derivatives, whereas X3LYP/6-31G and CAM-B3LYP/6-31G(d) in modeling the 13С NMR CSs of their sp2 fullerene carbon atoms. [ABSTRACT FROM AUTHOR]

The reaction of methylidenecycloalkanes with BF3·THF in the presence of Cp2TiCl2 as catalyst has been performed for the first time to obtain 1-fluoroboriranes spiro-fused to cycloalkanes and 1-methylcycloalk-1-enes formed as a result of isomerization of the initial olefin. The product structure was confirmed by one- (1H, 13C DEPT, 11B, 19F) and two-dimensional (COSY, HSQC, HMBC) NMR and mass spectra in combination with quantum chemical calculation of 13C chemical shifts. [ABSTRACT FROM AUTHOR]

Cycloboration of methylidenecycloalkanes with PhBCl2 in the presence of Cp2TiCl2 as catalyst was performed for the first time to afford previously unknown spiro-boracarbocycles in 70–80% yields. The structure and properties of the obtained spiro-boriranes were studied by 11B, 1H, and 13C NMR and DOSY experi-ments. 1-Phenyl-substituted boraspiranes were found to be stable in solution at room temperature for 24 h. [ABSTRACT FROM AUTHOR]

A2:1 β-cyclodextrin - histochrome complex was synthesized based on a comparison with experimental studies of histochrome and showed antioxidant activity prolonged to 16 d as compared with 6 d for histochrome in tests of the duration of the in vitro antioxidant effect. PMR measurements proved that a β-cyclodextrin - histochrome complex formed. Computer modeling of the β-cyclodextrin-histochrome complex showed that the head-to-tail complex corresponded to the energy minimum. [ABSTRACT FROM AUTHOR]

The reaction of methylidenecycloalkanes with BF3·THF in the presence of Cp2TiCl2 as catalyst has been performed for the first time to obtain 1-fluoroboriranes spiro-fused to cycloalkanes and 1-methylcycloalk-1-enes formed as a result of isomerization of the initial olefin. The product structure was confirmed by one- (1H, 13C DEPT, 11B, 19F) and two-dimensional (COSY, HSQC, HMBC) NMR and mass spectra in combination with quantum chemical calculation of 13C chemical shifts. [ABSTRACT FROM AUTHOR]

Cycloboration of methylidenecycloalkanes with PhBCl2 in the presence of Cp2TiCl2 as catalyst was performed for the first time to afford previously unknown spiro-boracarbocycles in 70–80% yields. The structure and properties of the obtained spiro-boriranes were studied by 11B, 1H, and 13C NMR and DOSY experi-ments. 1-Phenyl-substituted boraspiranes were found to be stable in solution at room temperature for 24 h. [ABSTRACT FROM AUTHOR]