10.1002/chem.201002076
The study presents the development of a series of eight new [2]rotaxane molecules, with a focus on the first sulfonamide interlocked system, designed to selectively recognize chloride anions in aqueous media. The research leverages a chloride-anion-templating synthetic pathway to create these [2]rotaxanes, whose three-dimensional interlocked-binding domains exhibit high chloride selectivity. The study utilizes 1H NMR spectroscopic titration to demonstrate the rotaxanes' chloride recognition capabilities and employs X-ray structural analysis and computational molecular dynamics simulations to elucidate the formation yields, anion binding affinities, and selectivity trends. The findings reveal that the rotaxanes can selectively bind chloride even in competitive aqueous solvent mixtures, with the binding affinity tunable through modifications such as electron-withdrawing substituents and charge increase. The research contributes to the advancement of anion recognition in supramolecular chemistry and has implications for nanotechnological applications.
10.1016/j.tetlet.2008.06.123
The study focuses on the synthesis of substituted 2-azabicyclo[3.2.1]octadienes, which are significant in the creation of natural products and biologically active compounds, through the ring expansion of substituted norbornadienes using toluenesulfonyl azide. The researchers explored the regioselectivity of the cycloaddition/rearrangement process with various mono- and disubstituted norbornadienes, finding that both types could be converted into the bicyclooctadiene ring system with high regiocontrol and in moderate to excellent yields. The study also investigated the impact of different substituent groups on the reaction's outcome, noting that electron-withdrawing groups resulted in little to no product, while hydroxymethyl derivatives provided a moderate yield of a single regioisomer. The synthesized 2-azabicyclo[3.2.1]octadienes can be further modified to yield highly substituted derivatives of the 2-azabicyclo[3.2.1]octane ring system, which is prevalent in natural products and pharmacologically active molecules, thus providing a valuable route for the synthesis of these complex structures.
10.1055/s-2004-831250
The study presents an efficient method for synthesizing esters and thioesters from corresponding carboxylic acids using Tetramethylfluoroformamidinium hexafluorophosphate (TFFH) as a coupling reagent. The research details the preparation of N-acyl-dithiocarbamates from carboxylic acids and 1,3-thiazolidine-2-thione with TFFH. It highlights TFFH's advantages over traditional reagents like Dicyclohexylcarbodiimide (DCC), including higher reactivity, fewer byproducts, and lower toxicity. The study also demonstrates the chemoselective acylation of dithiocarbamates using TFFH, which is beneficial for preparing aldehydes from carboxylic acids. The results show that TFFH is effective for a wide range of substrates, including those with sensitive functional groups, and can be used under mild conditions with high yields, making it a valuable reagent in organic synthesis.
10.1016/j.ica.2004.07.008
The research focuses on the synthesis, characterization, electrochemical behavior, and catalytic properties of dioxo-molybdenum(VI) and -tungsten(VI) complexes with novel asymmetric N2OS, and partially symmetric N2S2 and NOS2 N-capped tripodal ligands. The reactants used in the synthesis include various ligands such as [Hx(Ln)], [WO2Cl2(dme)], [MoO2(acac)2], and bases like triethylamine or KOH. The synthesized complexes were characterized using spectroscopic techniques such as NMR, IR, and mass spectrometry, and their molecular structures were established through X-ray diffraction analysis. The complexes' electrochemical properties were investigated using cyclic voltammetry, and their catalytic activities for the oxidation of allylic and benzylic alcohols were examined under both anaerobic and aerobic conditions. The study also explores the effect of different chelate ring sizes and donor atoms on the complexes' properties.
10.1007/s00706-011-0563-x
The research focuses on the development of an eco-friendly and efficient catalytic system for the synthesis of a series of new (E)-1-(benzylideneamino)-3-cyano-6-(trifluoromethyl)-1H-2-pyridones. These compounds are derived from the cyclocondensation reaction of benzylidene cyanoacetohydrazide with 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones, using a novel catalytic system consisting of triethylamine and a Lewis acid in the ionic liquid [BMIM][BF4]. The study emphasizes the comparison between this new system and traditional methods, highlighting that the products were only successfully synthesized using the new catalyst system. The experiments were conducted at room temperature, yielding products in moderate to good yields (42–87%). Various analytical techniques were employed to characterize the products, including NMR spectroscopy, GC-MS, and in some cases, X-ray diffraction, with elemental analysis and melting points also reported. The research underscores the potential of ionic liquids as green solvents, capable of being recycled and reused, thus reducing environmental impact.
10.1016/S0040-4039(01)01178-9
The research focuses on the synthesis of 5-(ω-sulfhydrylalkyl)salicylaldehydes, which are precursors for the preparation of alkanethiol-modified metal salens. These compounds are of interest for their potential use in modifying the surfaces of gold electrodes. The experiments involved multistep syntheses to obtain two specific alkanethiol-modified salicylaldehydes: 5-(2-sulfhydrylethyl)salicylaldehyde and 5-(6-sulfhydrylhexyl)salicylaldehyde. Key reactants included 4-methoxyphenethyl alcohol, hydriodic acid, Grignard reagent, paraformaldehyde, triethylamine, and thiourea, among others. The synthesis procedures involved refluxing, formation of Grignard reagents, column chromatography for purification, and treatment with base. The synthesized compounds were characterized using gas chromatography-mass spectrometry (GC–MS) and nuclear magnetic resonance (NMR) spectrometry to confirm their structures and purity.
10.1002/adsc.200700333
The research focuses on the copper-catalyzed multicomponent reactions (MCRs) of terminal alkynes, acid chlorides, and carbodiimides to synthesize functionalized propiolamidine derivatives. The study explores the efficiency of various bases and solvents to optimize the reaction conditions. The optimal catalytic system was found to be a combination of CuI, triethylamine (TEA), and acetonitrile (CH3CN), yielding the desired products in good to excellent yields. The experiments involved a suspension of carbodiimide and acid chloride, followed by the addition of anhydrous acetonitrile, TEA, CuI, and alkyne at room temperature under a nitrogen atmosphere. The reaction mixture was stirred, then extracted with CH2Cl2, washed with saturated NaHCO3 solution and water, dried over anhydrous MgSO4, and evaporated under vacuum. The residue was purified using silica gel column chromatography with petroleum ether/ethyl acetate as the eluent. The analysis of the reaction products was based on isolated yields, which were calculated based on the amount of N,N’-dialkylcarbodiimides used.
10.1080/00397910802419680
The research focuses on the efficient synthesis of 7-amino-3-hydroxyindan-1-one, a three-dimensional, three-point scaffold with potential applications in constructing focused compound libraries for biological interactions. The synthesis is achieved through a three-step process: first, reacting 4-nitrophthalic anhydride with ethyl acetoacetate, acetic anhydride, and triethylamine in methylene chloride to produce compound 10; second, hydrolyzing and decarboxylating compound 10 with trifluoroacetic acid in acetonitrile to yield 4-nitroindan-1,3-dione (11); and third, reducing compound 11 using catalytic hydrogenation with 10% Pd/C in methanol to obtain the final product, 7-amino-3-hydroxyindan-1-one (7). The structure of compound 7 was confirmed using heteronuclear multiple bond correlation (HMBC) spectral studies. The article also details the preparation of N-substituted derivatives of compound 7 and provides their physical constants, spectral data, and yields. Analytical techniques used include NMR spectroscopy, LC/MS, and melting point determination, ensuring the purity and structure of the synthesized compounds.
10.1007/s12039-012-0354-x
The research focuses on the synthesis and evaluation of a series of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinone derivatives as potential antibacterial and antifungal agents. The study involved the synthesis of twelve compounds, which were subjected to in vitro antibacterial testing against E. coli, S. aureus, K. pneumoniae, P. aeruginosa, and antifungal testing against C. albicans, A. niger, and A. flavus using the cup-plate method. The synthesized compounds were confirmed through spectral data interpretation, including Fourier Transform-Infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and elemental analysis. The experiments utilized various reactants such as pyruvic acid, o-phenylenediamine, ethylchloroacetate, potassium carbonate, and different aromatic aldehydes, along with chloroacetylchloride and triethylamine for the final compound formation. The structures of the synthesized compounds were elucidated using these analytical techniques, and their biological activities were assessed and compared with standard drugs to determine their potential as antimicrobial agents.
10.1016/j.tetlet.2012.02.081
The study presents a method for the N-arylation of amines and NH-heterocycles using NiCl2·6H2O as a recyclable heterogeneous catalyst under microwave exposure. The primary chemicals used include aryl halides, various amines, and NH-heterocycles as substrates for the coupling reaction, NiCl2·6H2O as the catalyst, and triethylamine (Et3N) as the base. These chemicals serve the purpose of forming carbon-nitrogen bonds in the synthesis of aryl amines, which are important in the production of drugs, materials, natural products, agrochemicals, and optical devices. The study highlights the advantages of using microwave energy for heating chemical reactions, which include reduced reaction times, increased product yields, and enhanced product purities. The process is solvent-free, does not require ligands, and the catalyst can be easily recovered and reused, making the protocol convenient, rapid, economical, and environmentally friendly.
10.1039/b403652b
The study focuses on the synthesis and evaluation of two new zinc ion-dependent oligonucleotide-based artificial nucleases (OBANs), OBAN 4 and OBAN 5. These OBANs are composed of 2'-O-methyl modified RNA oligomers conjugated to 5-amino-2,9-dimethylphenanthroline (neocuproine) via a urea linker. OBAN 4 features the catalytic group on a linker extending from the C-4 of an internal cytosine, while OBAN 5 has two neocuproine units attached via linkers from the C-5 position of uridine moieties. The synthesis involves conjugating the catalytic group to the amino linkers of the modified oligonucleotides by converting 5-amino-2,9-dimethylphenanthroline to phenylcarbamate and reacting it with oligonucleotides carrying primary aliphatic amines in aqueous buffer. Both OBAN systems are found to cleave RNA in bulged-out regions from non-complementary parts of the target sequences in the presence of Zn(II) ions, with differences in efficiency compared to previous systems discussed. The study also explores the influence of linker and linker position, as well as target RNA structure, on cleavage efficiency, providing insights into the development of more efficient OBAN systems for potential applications in life science and biotechnology.
10.1080/00397910802241407
The research presents the synthesis and characterization of a new series of hydroxy pyrazolines, which are nitrogen-containing heterocyclic compounds known for their broad spectrum of biological activities such as antitumor, immunosuppressive, antibacterial, anti-inflammatory, anticancer, antidiabetic, and antidepressant properties. The study begins with the preparation of 3-phenyl-1-(thiophen-2-yl)prop-2-en-1-one (chalcone 1) through the Claisen-Schmidt condensation of 2-acetyl thiophene with benzaldehyde. This chalcone 1 is then converted into 2,3-dibromo-3-phenyl-1-(thiophen-2-yl)propan-1-one (chalcone dibromide 2) by reacting with bromine in chloroform. Further reaction of chalcone dibromide 2 with various thiosemicarbazides in the presence of triethylamine in absolute ethanol yields hydroxy pyrazolines 3a–h. The synthesized compounds are characterized using IR, 1H NMR, and 13C NMR spectroscopy, with their purity confirmed by elemental analysis. The research also includes the preparation of substituted thiosemicarbazides used in the reaction, and the detailed experimental procedures for the synthesis of each compound are provided in the article.
10.1055/s-0034-1378361
The research focuses on the efficient synthesis of 2-alkynyl 1,3,4-oxadiazoles, which are significant in pharmaceutical and material sciences due to their potential bioactivity and applications in organic electronics. The study reports the first application of the Sonogashira reaction for the preparation of these oxadiazole derivatives. The experiments involved the palladium-catalyzed cross-coupling of 2-bromo-1,3,4-oxadiazoles with terminal alkynes under Sonogashira conditions, utilizing PdCl2(PPh3)2 and CuI as catalysts, and Et3N as a base in DMF solvent at 60°C. The reaction conditions were optimized to achieve high yields of products without side products. Various reactants, including different 2-bromo-1,3,4-oxadiazoles with electron-donating or electron-withdrawing groups and a range of terminal alkynes with aromatic, heteroaromatic, or aliphatic moieties, were used. The synthesized products were characterized using spectroscopic data, including IR, 1H NMR, 13C NMR, and ESI-MS, and compared with known compounds to confirm their structures.
10.1002/ejic.202000425
The research focuses on the synthesis of non-symmetric ruthenium(II) POCOP pincer complexes and their subsequent conversion into bimetallic derivatives through π-coordination of arenophile fragments. The study utilizes reactants such as [RuCl2(COD)]n, various POCOP pincer ligands based on the naphthoresorcinate backbone, and different organometallic fragments like [RuCp]+, [RuCp*]+, and [FeCp*]+. The experiments involve deprotonation of naphthoresorcinol by triethylamine, followed by reaction with chlorophosphines to form the POCOP ligands, and further coordination with ruthenium precursors to obtain the desired complexes. Single-crystal X-ray diffraction, DFT calculations, and various spectroscopic techniques (NMR, FTIR, and MS) were employed to characterize the molecular structures and confirm the formation of the complexes. The research also explores the selective synthesis of either Ru-Cl or Ru-H complexes by manipulating reaction conditions and investigates the potential of these complexes in catalytic processes, such as the reduction of carbon dioxide.
10.1016/j.tetlet.2013.07.029
The study presents a copper-catalyzed one-pot synthesis of alkynyl imidates and alkynyl thioimidates through a coupling reaction involving terminal alkynes, trichloroimidates generated in situ from trichloroacetonitrile and benzyl alcohols or thiols. The key chemicals include phenylacetylene as a model terminal alkyne, trichloroacetonitrile as a precursor for trichloroimidates, and benzyl alcohol or thiol as the source of the imidate or thioimidate group. Copper iodide (CuI) acts as the catalyst, and triethylamine (Et3N) is used as a base. The reaction is optimized in acetonitrile at room temperature, yielding the desired products in good yields. The mechanism involves the formation of a copper acetylide intermediate, which reacts with the trichloroimidates to form a tetrahedral intermediate, followed by the elimination of CuCCl3 to produce the final products. This method offers a versatile and efficient route for synthesizing functionalized alkynes with readily available starting materials and catalysts.
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