10.1021/om034385g
The study investigates the reactions of 3-(pentafluorophenyl)indene and (pentafluorophenyl)cyclopentadiene with tetrakis(dimethylamido)titanium(IV), resulting in the formation of products where one or both ortho fluorines of the C6F5 group are replaced by dimethylamino groups. This suggests a titanium-mediated, intramolecular nucleophilic aromatic substitution mechanism. The research led to the isolation of organic products and the conversion of substituted cyclopentadiene to a ferrocene derivative. The study provides insights into the selective activation of polyfluorinated organic compounds, a significant challenge in synthetic chemistry, and contributes to the understanding of transition metal complex mechanisms for C-F activation.
10.1039/c39900000441
This research aimed to isolate exceptionally persistent nitrogen-centered free radicals, specifically N-arylthio-2,4,6-triphenylanilino radicals (2), which are oxygen-insensitive and can be isolated as pure radical crystals. These radicals are of interest due to their potential connection with organic ferromagnetic materials. The researchers generated thioaminyl radicals (2) by oxidizing N-arylthio-2,4,6-triphenylanilines (1) with lead dioxide (PbO2) in the presence of potassium carbonate (K2CO3). The resulting radicals were found to be remarkably stable, even in the presence of oxygen, and did not dimerize even at low temperatures. This exceptional persistence was attributed to electronic stabilization through conjugative delocalization of the unpaired electron and steric protection provided by the three phenyl groups on the anilino benzene ring. The isolation process involved a benzene solution of (1) being stirred with PbO2 and K2CO3, followed by filtration, solvent removal by freeze-drying, and crystallization from hexane. The structures of the radicals were confirmed through IR spectra and elemental analysis.
10.1021/om00084a013
The study investigates the photochemical reactions of phosphine-substituted cobalt carbonyl complexes, specifically focusing on [Co(CO)3L2][Co(CO)4] and Co2(CO)8L2 (L = tributylphosphine). The major photochemical reactions are initiated by the photolysis of the cation Co(CO)3L2?, which leads to ligand dissociation, electron transfer, and metal-metal bond cleavage. In the presence of CO, H2, or excess phosphine, various products are formed, including Co2(CO)8L2, HCo(CO)3L, HCo(CO)4L2, and [Co(CO)2L3]?. The neutral complex Co2(CO)8L2 is photostable in the absence of phosphine but undergoes photosubstitution or photodisproportionation in the presence of excess phosphine, depending on the solvent (hexane or methanol). The study provides insights into the mechanisms of these photochemical processes and their potential applications in catalysis.
10.1134/S1070428010090319
The research presents an investigation into the reactions of substituted 1-nitro-2-phenylethenes with N-phenacyl- and N-acetonylisoquinolinium bromides, aiming to expand the understanding of reactions involving nitrophenylethenes and azomethine ylides. The experiments involved the reaction of phenylethenes I and II with precursors of azomethine ylides, III and IV, using sodium hydride in dry dioxane to generate active azomethine ylides, which then underwent 1,3-dipolar cycloaddition to form substituted tetrahydropyrroloisoquinolines V–VIII in yields of 55–62%. The structures of these compounds were confirmed using IR and 1H NMR spectroscopy, as well as elemental analysis. Additionally, the carbonyl group in the cycloadducts allowed for further heterocyclization with hydrazine hydrate to synthesize novel substituted hexahydrotriazinoindolizines IX–XII. The IR spectra showed characteristic absorption bands for the NO2 and CN groups, and the 1H NMR spectra provided details on the protons of the pyrrolidine and isoquinoline rings. The reaction progress and compound homogeneity were monitored using TLC on Silufol UV-254 plates with a solvent mixture of acetone and hexane.
10.1021/ja029059r
The research focuses on elucidating the supramolecular structure of benzoxazine oligomers using a combination of molecular modeling, density functional theory (DFT) calculations, and advanced solid-state nuclear magnetic resonance (NMR) experiments. The study characterizes intramolecular hydrogen bonds as the driving forces behind the ring-shaped and helical conformations observed in trimeric and tetrameric units. The experiments involved the synthesis of model trimer and tetramer structures, which were then subjected to fast magic-angle spinning (MAS) 1H NMR spectra to assign resonances of protons forming hydrogen bonds. The experiments use n-hexane, acetone, chloroform, methylamine, p-cresol, and formaldehyde as solvents and reagents. DFT-based geometry optimizations and 1H chemical-shift calculations were used to validate and refine the structural models. Additional analyses included homonuclear 1H-1H double-quantum NMR spectra to identify local proton-proton proximities and quantitative 15N-1H distance measurements obtained from dipolar spinning sideband patterns. These experimental and computational approaches collectively supported the proposed helical geometry of the benzoxazine polymer, which could account for the material's unique chemical properties.
10.1039/b613641a
The study presents a method for converting (sp3)C–F bonds in alkyl fluorides to (sp3)C–X bonds (where X = Cl, C, H, O, S, Se, Te, N) using organoaluminium reagents with Al–X bonds in a hexane solution. The purpose of these chemicals is to facilitate the replacement of fluorine atoms with other atoms or groups, which is a challenging task due to the inertness of C–F bonds. The study demonstrates that this conversion can be achieved under mild conditions, with primary alkyl fluorides reacting efficiently to form various products such as alkyl chlorides, alkanes, and other derivatives. The reagents serve to cleave the C–F bond and promote the substitution reaction, which is significant in organic chemistry for the synthesis of various compounds.
F,
Xn,
N
