10.1007/s10593-010-0647-2
The study focuses on the intramolecular cyclization of 1-[1-alkylsulfanyl-2-phenyl-2-(phenylhydrazono)ethylidene]pyrrolidinium salts, which are synthesized by the alkylation of thioamide with benzyl, allyl, and propargylsulfanyl groups in the presence of cesium carbonate in DMF at room temperature. These pyrrolidinium salts can be efficiently converted into 1,3-diphenyl-6,7,8,8a-tetrahydro-1H-pyrrolo[2,1-c]-1,2,4-triazine-4-thione derivatives in good yields. The research demonstrates that this cyclization method is general for alkyl derivatives of arylhydrazonothioacetamides, expanding the scope of this reaction type. The synthesized pyrrolotriazines are of practical interest due to their potential high antitumor activity, making them promising candidates for biological investigation. The study was financially supported by the Russian Basic Research Fund and includes detailed experimental procedures, characterization data, and comparison of the reaction outcomes with different bases and solvents.
10.1021/ol2001039
The research focuses on the development of a highly enantioselective method for constructing a quaternary carbon center by catalytic enantioselective cross-aldol reactions between acetone and aryl trihalomethyl ketones, using N-(heteroarenesulfonyl)prolinamides as organocatalysts. The experiments involved the reaction of various trihalomethyl ketones (both trifluoromethyl and trichloromethyl) with acetone, utilizing N-(8-quinolinesulfonyl)prolinamide as the catalyst of choice, which was found to be highly efficient. The reactants included different aryl trifluoromethyl ketones and trichloromethyl ketones, along with acetone, and the products were analyzed for yield and enantioselectivity using high-performance liquid chromatography (HPLC) and X-ray crystallography to determine the absolute configuration of certain products. The study also employed molecular orbital calculations to elucidate the role of hydrogen bonding in exerting enantioselectivity, revealing that the interaction between the sulfonimide proton and the 8-quinolyl nitrogen atom is crucial for the reaction's selectivity.
10.1021/om00100a023
The research focuses on two main studies within the field of organometallic chemistry. The first study investigates the electrochemical behavior of a mixture of isomers, specifically cis- and trans-Cr(CO)4(P(OMe)3)2, and the reversible electrochemical responses that involve significant structural changes. The researchers concluded that the observed single wave Nernstian response for the oxidation of the mixture is due to rapid isomerization of the oxidized cis+ species and/or a rapid cross redox reaction, which leads to the redox responses always being observed at the trans+/transO redox potential, irrespective of the equilibrium or nonequilibrium mixtures of the isomers present in the bulk solution. The second study presents a method for the stoichiometric hydroformylation of coordinated acetone using a zirconium complex, Cp2Zr[(μ-0C)Mo(CO)3Cp][μ2,η1-CMe2O)Zr(Me)Cp2], which undergoes CO insertion into its Zr-C bond, leading to the formation of α-hydroxyisobutyraldehyde. The researchers found that the acetone ligand in the complex is unreactive towards potential insertion reagents other than CO. The chemicals used in these processes include various organometallic compounds, such as chromium and zirconium complexes, as well as solvents like toluene and acidifying agents like CF3COOH.
10.1134/S1070363220040015
The research investigates the three-component condensation reaction of propan-2-one (acetone) with formaldehyde and propane-2-thiol in the presence of sodium hydroxide to produce various ?-keto sulfides. The study aims to determine the optimal conditions for forming different products, namely 4-[(propan-2-yl)sulfanyl]butan-2-one (1), 3-{[(propan-2-yl)sulfanyl)methyl]but-3-en-2-one (2), and 4-[(propan-2-yl)sulfanyl]-3-{[(propan-2-yl)sulfanyl)methyl}butan-2-one (3), by varying the amount of sodium hydroxide. The key findings are that the product ratio depends on the quantity of sodium hydroxide used. When the molar ratio of acetone : formaldehyde : propane-2-thiol : sodium hydroxide is 1 : 1 : 1 : 0.03, compound 1 is initially formed, which then transforms into compounds 2 and 3. Increasing the amount of sodium hydroxide to 0.4 mol results in a maximum conversion of propane-2-thiol to 99% within 5 hours, with bis-sulfide 3 being the major product. The study concludes that the formation of compound 2 involves an aldol condensation of compound 1 with formaldehyde, and compound 3 is produced via a base-catalyzed thia-Michael addition of propane-2-thiol to the C=C double bond of compound 2.
10.1023/A:1023419530311
The study in the provided document investigates the reaction of quaternary ammonium salts with a 1,1-dimethylbut-2-yne-1,4-diyl common group with aqueous alkali. The research focuses on the intermediate formation of 1,2-cleavage products rather than 1,4-cleavage products. When both nitrogen atoms have allylic groups, a rearrangement followed by cleavage and substitution occurs, leading to the formation of methyl isopropyl ketones. Salts with two 3-methylbut-2-en-1-yl groups result in the cleavage of isoprene. The study also explores the reactions of 1,4-diammonium salts with two methyl substituents in the but-2yne-1,4-diyl common group under the influence of aqueous alkali, detailing the products and mechanisms involved in these chemical transformations.
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.
10.1016/S1872-2067(12)60693-7
The study focuses on the synthesis of 4H-pyran derivatives using a silica-bonded N-propylpiperazine sodium n-propionate (SBPPSP) as a recyclable catalyst. The catalyst was prepared from commercially available and inexpensive starting materials and was used to catalyze the synthesis of various 4H-pyran derivatives, including 3,4-dihydropyrano[c]chromenes, 2-amino-4H-pyrans, 1,4-dihydropyrano[2,3-c]pyrazoles, and 2-amino-4H-benzo[e]chromenes. The chemicals used in the study included aromatic aldehydes, malononitrile, dimedone, ethyl acetoacetate, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, and α-naphthol, which served as reactants in the multi-component reactions to form the desired 4H-pyran derivatives. The purpose of these chemicals was to participate in condensation reactions under refluxing aqueous ethanol conditions, with SBPPSP facilitating the process and being easily recoverable and reusable, highlighting the environmental and economic benefits of the method.
10.1021/om010024u
The research focuses on the synthesis and characterization of new dihydride- and alkene-η6-arene complexes of iridium, which are significant in organometallic chemistry and have potential applications as catalysts in various transformations. The study aimed to develop a versatile synthetic route to these iridium complexes containing bulky alkylphosphines, which were found to be active catalysts for the hydrogenation of a variety of unsaturated substrates. The chemicals used in the process include iridium derivatives with general formulas [(η6-arene)IrH2(PR3)]BF4 and [(η6-arene)Ir(η2-C2H4)(PiPr3)]BF4, where arene ranges from benzene to various substituted benzenes and alkenes, and PR3 represents different phosphine ligands. The synthesis involved treatment of [Ir(μ-OMe)(cod)]2 with [HPR3]BF4, followed by reaction with H2 in acetone/benzene mixtures, and further substitution reactions with different arenes. The research concluded that these complexes not only serve as efficient hydrogenation catalysts but also act as convenient precursors for the synthesis of new η6-arene complexes of iridium with alkene ligands.
10.1016/S0040-4020(97)00298-6
The research focuses on the synthesis of (4S)-hydroxymethyl-(2R)-(2-propyl)-butyrolactone, an important hydroxyethylene isostere chiron, which is a key structural component in the development of drugs targeting enzymes like HIV-protease and renin. The study aimed to develop a practical and efficient route for the stereocontrolled introduction of a 2-propyl group into (4S)-hydroxymethyl-1,4-butyrolactone using enolate chemistry. Several approaches were explored, leading to the development of a practical synthesis for both (2R)- and (2S)-isomers. The successful methods involved a cross-aldol reaction, radical-mediated deoxygenation, and selective reduction steps, using chemicals such as lithium enolate, acetone, triphenyltin hydride, and TBDPS (tert-butyldiphenylsilyl) group for protection, among others. The research concluded with the identification of viable routes for the preparation of all four diastereomers, with a particular emphasis on the trans-2,4-substituted butyrolactones, which are amenable to large-scale preparation.
10.1016/j.tetasy.2008.02.023
The study, titled "Convenient enantioselective synthesis of b-tri?uoromethyl-baminoketones by organocatalytic asymmetric Mannich reaction of aryl tri?uoromethyl ketimines with acetone," investigates the use of LL-proline as a catalyst to synthesize chiral b-aryl-b-tri?uoromethyl-b-aminoketones through an asymmetric Mannich reaction between aryl tri?uoromethyl ketimines and acetone. The researchers found that this method yields high enantiomeric purity (74–92% enantiomeric excess) and good yields (up to 86%). The study explores the reaction conditions, such as solvent effects and catalyst concentration, and demonstrates the versatility of the method by synthesizing several derivatives. Additionally, the synthesized aminoketones are further transformed into other useful compounds, such as 1,3-aminoalcohols and 1,3-diamines, showcasing the potential applications of these chiral fluorine-containing compounds in pharmaceuticals and other biologically active agents.
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