10.1021/la904827d
The study investigates the influence of surfactant architecture on the properties of polystyrene-montmorillonite (PS-MMT) nanocomposites. A variety of surfactants were designed and synthesized to modify clay, aiming to understand how their chemical structure affects the nanocomposite's morphology after polymerization. The research focused on the behavior of surfactant-modified clays at three stages: post ion-exchange, after dispersion in styrene monomer, and following polymerization. The compatibility and prediction of the nanocomposite morphology were assessed based on the styrene monomer's ability to swell the surfactant-modified clay. Key factors identified for achieving exfoliated morphologies included the position of the ammonium group, the presence of a polymerizable group, surfactant solubility in the monomer, the length of the alkyl chain, and the concentration of surfactant used for clay modification. Techniques such as small-angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), wide-angle X-ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA), and thermal gravimetric analysis (TGA) were utilized to characterize the clay-polymer interactions and the properties of the resulting composites. The findings are expected to enhance the design of clay modifications for polymer nanocomposites.
10.1071/CH16710
The study reports on the successful synthesis and characterization of two 28-membered, 2,2'-bipyridine-containing macrocycles in high yield. The first macrocycle was formed through a Williamson ether synthesis, and upon reduction with sodium borohydride, the second macrocycle was produced quantitatively. These macrocycles, which contain a 2,2'-bipyridine unit, are potentially useful components for creating a variety of interlocked architectures, including catenanes, rotaxanes, and molecular machines. The research builds upon previous work by Sauvage, Stoddart, and Feringa, who were awarded the 2016 Nobel Prize in Chemistry for their contributions to the design and synthesis of molecular machines, and it aims to improve upon the yield-limiting macrocyclisation reactions that have historically been a challenge in the field. The study also discusses the use of high-yielding synthetic strategies and the potential for future investigations into the metal-complexation properties of these ligands and their application in forming interlocked structures.
10.14233/ajchem.2014.16893
The research primarily focuses on the synthesis, characterization, and in vitro antitumor activity evaluation of novel Schiff base compounds containing a pyrazole group. The synthesis involved the condensation reaction of 1-arylpyrazol-4-carbaldehyde with benzene hydrazine or phenylhydrazine hydrochloride, using methanol as a solvent and refluxing at 80°C for 2 hours. The reaction was optimized to avoid the use of additional catalysts to prevent complex post-processing. The synthesized compounds were purified through crystallization using a mixture of ethanol and dichloromethane. Characterization of the compounds was achieved using nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, mass spectrometry (MS), and elemental analysis. The in vitro antitumor activity was assessed by testing the compounds B2 and B4 against the K562 human leukemia cell line using the MTT assay method, with aminonide as a reference substance. The study found that these compounds exhibited antiproliferative activity against K562 cells, inhibiting their growth.
10.1021/jo0015974
The research focuses on the synthesis of R-keto esters and amides, which are crucial functional groups for inhibitors of hydrolytic enzymes such as serine and cysteine proteases. The study extends the method of oxidative cleavage of cyanoketophosphoranes using dimethyldioxirane as a mild and selective oxidant, followed by trapping with nucleophiles to yield the desired R-keto compounds. The experiments involved the preparation of cyanoketophosphoranes by coupling corresponding carboxylic acids with (cyanomethylene)phosphorane in the presence of EDCI. The oxidative cleavage was performed by adding dimethyldioxirane to solutions of cyanoketophosphoranes in MeOH for esters or in CH2Cl2 at -78 °C for amides, followed by the addition of the appropriate amine or alcohol nucleophile. The analyses used to characterize the products included flash column chromatography, analytical TLC, NMR spectroscopy (1H and 13C), infrared spectroscopy (IR), electron impact mass spectrometry (EIMS), and high-resolution mass spectrometry (HRMS). The study successfully demonstrated a mild and efficient method for synthesizing R-keto esters and amides with short reaction times and simple workup procedures.
10.1134/S1070363211010208
The research focuses on the synthesis of substituted 4H-[1,3]thiazino[3,2-a]benzimidazol-4-ols using N-tert-butyl-1-aza-1,3-enynes and symmetrically substituted 2-mercaptobenzimidazoles in water-alcohol solutions. The reaction is chemo- and regioselective, yielding a series of fused [1,3]thiazin-4-ols (IVa–IVf) without the need to isolate intermediates. The structures of these compounds were confirmed through 1H and 13C NMR spectroscopy and X-ray diffraction data. The experiments involved the addition of 2-mercaptobenzimidazole to N-tert-butyl-1-aza-1,3-enynes in methanol, sometimes with a DMF admixture, leading to the formation of the desired compounds with high melting points. The presence of water and DMF in methanol facilitated the hydrolysis of the intermediate [1,3]thiazine-4-tert-butylamine to the final [1,3]thiazin-4-ol products. The crystallographic data of one of the compounds, IVa, was deposited at the Cambridge Crystallographic Data Center with the reference number 757744.
10.1016/j.tet.2008.01.120
The research focuses on the isolation and structural elucidation of four novel xenicane diterpenoids, xenimanadins AeD (1e4), from the Indonesian soft coral Xenia sp. The study employed methanol extraction followed by medium pressure liquid chromatography (MPLC) and high-performance liquid chromatography (HPLC) for purification. The structures of the metabolites were determined using extensive NMR data interpretation and the modified Mosher method. The compounds were tested for cytotoxic potential against tumor cell lines. Reactants used in the experiments included methanol for extraction, (R)- and (S)-MTPA chloride for stereochemical determination, and various solvent mixtures for chromatography. Analyses utilized included optical rotation, infrared spectroscopy (IR), nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and high-resolution electron impact mass spectrometry (HREIMS).
10.1016/S0022-328X(99)00709-3
The study in the Journal of Organometallic Chemistry focuses on the direct nucleophilic displacement of halides (chlorine or iodine) in compounds with the formula (Me3Si)3CSiRRX, where R and R represent various organic groups. The researchers investigated the reactions of these compounds with nucleophiles such as KOCN, KSCN, KCN, or NaN3 in different solvents like CH3CN, MeOH, and DMSO, or CH3CN mixed with H2O. The study explores the influence of steric hindrance on the reactivity of silicon centers bearing the bulky trisyl group (Tsi). It was found that by reducing the steric hindrance or using linear nucleophiles, direct bimolecular displacement reactions occur without the observation of rearrangement. The study also successfully synthesized new compounds with different groups and examined their reactivity with the mentioned nucleophiles, providing insights into the ease of reactions on silicon centers bearing the bulky trisyl group.
10.1021/ol060045q
The study presents a Pd/C-catalyzed method for the deoxygenation of phenolic hydroxyl groups in phenol derivatives, converting them into aryl triflates or mesylates using magnesium metal in methanol (MeOH) at room temperature. The key innovation is the use of ammonium acetate (NH4OAc) as an additive, which significantly enhances the reaction's reactivity and rate. This approach is environmentally friendly, widely applicable, and operates under mild conditions without the need for a phosphine ligand or hydrogen gas. The method is effective for a variety of aryl triflates and mesylates, offering a practical and efficient route for deoxygenation in synthetic organic chemistry. The researchers also explored the reaction mechanism, suggesting that it involves an initial single electron transfer (SET) from magnesium to the palladium-activated aromatic ring, leading to the formation of an anion radical that subsequently eliminates the (trifluoro)methane sulfonic anion to produce the reduced arene product.
10.1039/c5nj02378e
The study presents a novel one-pot method for the catalytic cyclopropanation of various alkenes with unsubstituted hydrazones. The process utilizes iodosobenzene as an oxidant to convert hydrazones into diazo compounds, which are then cyclopropanated in the presence of a nickel(II) catalyst, Ni(OH)2. This method allows for the efficient generation of cyclopropane products under mild conditions (80°C) within a short time frame (5 minutes to 4 hours) and with moderate to good yields (42–91%). The protocol is applicable to a wide range of substrates, including aryl alkenes with different electronic effects, aliphatic alkenes with halogen functional groups, and alkyl acrylates. The study also explores the reaction mechanism and provides a promising approach to synthesizing cyclopropane compounds, which are prevalent in natural products and have significant value in pharmaceutical chemistry.
10.1248/cpb.23.677
The research focuses on the photolyses of steroidal oxime acetates, specifically examining the photo-methanolysis of the C-N and NO-Ac groups to the CO and NOH groups, respectively. The purpose of the study was to investigate the photo-Beckmann rearrangement of oxime esters within the context of steroidal chemistry. The researchers conducted photolysis on two steroidal oxime acetates, 6-acetoximino-3β-acetoxy-5a-cholestane (1) and 6-acetoximino-3β-acetoxycholestan-5a-ol (7), in methanol, leading to the formation of various nitrogen-free and nitrogen-containing compounds. The conclusions drawn from the study suggest that the primary photolysis of these compounds involves the comparable conversion of C-N and NO-Ac groups to CO and NOH groups, respectively.
Xn, 
T, 
F
