10.1021/ja2118442
The research aims to investigate the structures and reactivities of nitrile imines, which are significant in organic synthesis and 1,3-dipolar cycloadditions leading to various compounds like pyrazoles and pyrazolines. The study focuses on several nitrile imines that were generated photochemically or thermally and examined using infrared (IR) spectroscopy within argon (Ar) matrices at cryogenic temperatures. The researchers analyzed the impact of substituents on the structures and IR absorptions of nitrile imines computationally at the B3LYP/6-31G* level. The IR spectra were compared with calculated anharmonic vibrational spectra, showing a good agreement and indicating that the spectra accurately reflect the structures of nitrile imines. The study concluded that nitrile imines with IR absorptions above 2200 cm?1 have propargylic structures with a CN triple bond, while those with absorptions below about 2200 cm?1 are more likely to be allenic. All nitrile imines isomerize to the corresponding carbodiimides through both thermal and photochemical processes. The chemicals used in this process include a range of nitrile imines such as Ph-CNN-H, Ph-CNN-CH3, Ph-CNN-SiMe3, Ph-CNN-Ph, and the boryl-CNN-boryl derivative, among others, which were subjected to various experimental conditions to observe their structural behaviors and rearrangements.
10.1016/S0022-328X(00)82505-X
The study investigates the chemical behavior of monomeric pyrazol-1-ylboranes, specifically focusing on the preparation and reactions of 1,3-dimethyl-2-(pyrazol-1’-yl)-1,3,2-diazaboracyclopentanes. The researchers prepared two new species of these compounds and examined their interactions with pyrazoles and (dimethylamino)dialkylboranes. They found that the boron in these compounds exhibits significant Lewis acidity, leading to the formation of 1:1 molar adducts with pyrazoles and facilitating ligand exchange reactions with (dimethylamino)dialkylboranes to produce B-tetraalkylpyrazaboles. The study also suggests that the bridging hydrogen in the adducts is delocalized, supported by NMR spectroscopic evidence and preparative experiments. The findings provide insights into the coordination chemistry of poly(pyrazol-1-yl)borate ions and their potential applications in forming chiral centers when complexed with transition metals.
10.1016/j.tet.2008.11.036
The research primarily focuses on the arylation reactions of NH-heterocycles, such as pyrazole, 3-(trifluoromethyl)pyrazole, imidazole, and pyrrole, with 2,4-difluoroiodobenzene, facilitated by both copper catalysis and SNAr reactions. The study aims to explore the regioselective reactions and multiple substitutions to synthesize a range of new N-arylated heterocycle derivatives. The reactants include various NH-heterocycles and 2,4-difluoroiodobenzene, with copper catalysts like Cu2O and ligands such as salicylaldoxime utilized in some reactions. The analyses involved the use of 1H, 13C, and 19F NMR spectroscopy, IR spectroscopy, and mass spectrometry to determine the structures and purities of the synthesized compounds, along with X-ray crystallography for certain products to confirm their regiochemistry. The research also includes a Suzuki–Miyaura reaction to extend the utility of the synthesized arylation products.
10.1002/anie.201306511
The research focuses on the development of a traceless directing group strategy for C-H borylation reactions of nitrogen heterocycles and anilines. The main content revolves around the use of the (pinacolato)boron (Bpin) group as a traceless directing group, which can be readily installed and removed without additional steps, offering an alternative to traditional methods that require installation and removal of directing groups. The experiments involved the borylation of various substrates, including pyrroles, indoles, azaindoles, pyrazoles, and anilines, using the Bpin group. Reactants such as HBpin and iridium catalysts were used, along with tertiary amines to facilitate N-borylation. The analyses included monitoring the reactions by 1H and 11B NMR spectroscopy, and evaluating the yields and selectivity of the borylated products. The study demonstrated that the Bpin-directed approach is operationally simpler and generally higher yielding than the Boc-directed counterparts, and it expands the scope of C-H borylation by enabling functionalization at different positions on the substrates.
10.1016/j.bmcl.2013.01.054
The study focuses on the design, synthesis, and in vitro evaluation of a series of pyrazole-based fatty acid binding protein (FABP) 3 ligands. The researchers aimed to develop subtype-selective FABP ligands, specifically targeting heart fatty acid binding protein (FABP3), which is involved in lipid homeostasis and the uptake and transport of fatty acids towards mitochondrial β-oxidation systems. The study utilized a structure-guided approach, comparing the X-ray crystallographic structures of adipocyte FABP (FABP4) with the selective inhibitor BMS309403 and FABP3 with elaidic acid. Key chemicals used in the study include chalcone derivatives, substituted phenylhydrazines HCl, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) for oxidation, BBr3 for demethylation, and various alkyl bromo alkanoates for alkylation. These chemicals were used to synthesize 1,3,5-trisubstituted pyrazole derivatives, which were then tested for their binding-inhibitory activity towards FABP3 and FABP4. The purpose of these chemicals was to create ligands that could selectively bind to FABP3, potentially leading to the discovery of new drugs for the treatment of conditions related to lipid metabolism.
10.1139/v80-010
The study investigates the preparation, characterization, and reactions of N-tert-butyldimethylsilyl derivatives of various heterocyclic compounds, including imidazole, 2-methylimidazole, 4-methylimidazole, benzimidazole, pyrazole, 1,2,4-triazole, and benzotriazole. These derivatives were synthesized using tert-butyldimethylsilyl chloride and the corresponding heterocyclic compounds. The products were identified and characterized using carbon and proton nuclear magnetic resonance (NMR), mass spectrometry, and elemental analysis. The study confirmed the absence of intermolecular silyl exchange at ambient temperature through carbon NMR spectra, but noted that such exchange occurred at elevated temperatures (130-160°C). The study also explored the reaction of these silyl derivatives with dimethylsulfoxide (DMSO), resulting in the formation of N-(methylthio)methyl derivatives of the heterocycles. The mechanism for this reaction involves a Pummerer rearrangement, and the products were characterized using various analytical techniques, providing insights into the stability and reactivity of these compounds under different conditions.
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