Refernces
10.1016/S0040-4020(01)97712-9
A study on the oxidation of organic sulfur compounds such as disulfides, thiolsulfinate, thiolsulfonate, thiol, sodium thiolate, and sodium sulfinate using superoxide anion generated from potassium superoxide and 18-crown-6-ether under mild conditions. The research, conducted by Shigeo Oae and colleagues at the University of Tsukuba, demonstrates that these compounds are readily oxidized to both sulfinic and sulfonic acids. The study also notes that sulfide and sulfoxide did not react with the superoxide anion. The oxidation reactions were found to be more effective in polar solvents like pyridine and acetonitrile compared to less polar solvents like benzene. The relative reactivities of the compounds were observed in the order: thiolsulfinate > thiolsulfonate > disulfide = sodium thiolate > sodium sulfinate. The study provides insights into the fundamental nature of the reactions of superoxide anion with organic sulfur compounds and discusses the potential involvement of nucleophilic attack and electron transfer processes in these oxidations.
10.1016/S0957-4166(01)00391-3
The study in the provided scholarly article focuses on the synthesis of specific octahydroquinolin-7-ones, which are compounds derived from aspidosperma alkaloids and are important in asymmetric synthesis. The researchers synthesized the enamine (?)-(1’S)-5-ethyl-1-(1’-phenylethyl)-1,2,3,4-tetrahydropyridine 4 and used it to create (?)-(1’S,4aS,8aR)- and (+)-(1’S,4aR,8aS)-4a-ethyl-1-(1’-phenylethyl)-octahydroquinolin-7-ones 5 and 6. Key chemicals used in the study include (?)-(S)-1-phenylethylamine, 4-formyl-hexanoic acid methyl ester, LiAlH4/THF for reduction, and methyl vinyl ketone (MVK) in the presence of KOH/18-crown-6/methanol. These chemicals served various purposes, such as starting materials for the synthesis, a reducing agent, and reagents for the condensation reaction to form the desired octahydroquinolin-7-ones. The study also reports an X-ray study of compound 6, which confirmed the cis-fused ring structure and absolute configurations of the stereogenic centers. The purpose of these chemical syntheses was to explore the applications of 3,4-dihydro-1H-pyridin-2-ones in asymmetric synthesis and to prepare compounds 5 and 6 with specific stereochemistries.
10.1021/jo00066a032
The research focuses on the stereoselective formation of glucal epoxides, which are crucial intermediates in the synthesis of oligosaccharides and other carbohydrate derivatives. The study aimed to find an alternative approach to the existing method of dimethyldioxirane (DMD) oxidation, which has limitations such as the need for rigorous drying and difficulty in scaling up. The researchers explored the cyclization of bromohydrins as a route to glucal epoxide formation, using chemicals such as N-bromoacetamide (NBA), sodium hydride (NaH), potassium hydride (KH), 18-crown-6, sodium phenylthiolate, sodium azide, methoxide, and benzyloxide. They observed that the reaction conditions significantly affected the diastereoselectivity of the epoxide formation, leading to different ratios of a-manno and β-gluco products. The study concluded that the formation and cyclization of bromohydrins offer an alternative route for glucal epoxide synthesis, with potential applications to other carbohydrate substrates, and highlighted the importance of metal ions and solvents in modifying the relative reactivities of the anomeric alkoxides, which influence the stereoselectivity of the cyclization process.
10.1021/jo00298a044
The research investigates the reactivity of monohalonitrobenzenes in alkaline 2-propanol solutions of potassium 2-propoxide, focusing on the competition between radical and nonradical reaction pathways. The study aims to identify distinct reaction paths, including hydro dehalogenation to nitrobenzene, alkoxy dehalogenation via the SNAr mechanism, and nitro reduction to azoxy and anilino derivatives via nitroso intermediates. The research concludes that, with the exception of 2- and 4-fluoronitrobenzene, radical processes are generally faster than the SNAr reaction. The study also reveals that the presence of oxygen and cation complexing agents, such as 18-crown-6, significantly influence the reaction pathways and product distributions. Key chemicals used in the process include various halonitrobenzenes (X = F, Cl, Br, I), potassium 2-propoxide, 2-propanol, and 18-crown-6 ether.
10.1021/acs.orglett.0c02635
The study presents the development of a catalytic system for the C-alkylation of N-heterocyclic compounds, such as pyridine, pyrimidine, pyrazine, quinoline, quinoxaline, and isoquinoline, using alcohols. The process is based on a hydrogen-borrowing approach and utilizes [Cp*IrCl2]2 as the catalyst precursor, combined with potassium t-butoxide and 18-crown-6-ether. This method is environmentally friendly as it only produces water as a byproduct. The researchers optimized the reaction conditions and demonstrated the system's versatility by applying it to various substrates, achieving good to excellent yields. The study also proposed a possible reaction mechanism involving three steps: hydrogen transfer from alcohol to iridium catalyst, cross-aldol-type condensation, and transfer hydrogenation. The developed catalytic system is expected to contribute to the synthesis of pharmaceuticals and functional materials.
10.1021/om0102551
The research presents a study on the reduction reactions of uranium(IV) thiolates, Cp2U(SR)2 (where Cp is η-C5Me5 and R is Ph, Me, iPr, or tBu), using sodium amalgam to produce the corresponding uranium(III) complexes Na[Cp2U(SR)2] (R = Ph, Me, iPr) or the uranium(IV) sulfide Na[Cp2U(StBu)(S)]. The purpose of the study was to investigate the stability and reactivity of these complexes, particularly focusing on C-H and C-S bond cleavage. The research concluded that the stability and reactivity of the U(III) anions [Cp2U(SR)2]- and their oxidation following C-S or C-H bond cleavage were significantly influenced by the nature of the R group. The uranium(III) complexes Na[Cp2U(SPh)2] and [Na(18-crown-6)][Cp2U(SR)2] (R = Me, iPr) could be isolated, with the isopropyl thiolate derivative being the first crystallographically characterized thiolate of U(III). The study also found that low-valent, coordinatively unsaturated species could facilitate the C-S bond cleavage reaction, which is significant for catalytic desulfurization processes. Key chemicals used in the process included sodium amalgam, 18-crown-6, tetrahydrofuran (THF), and various organometallic compounds such as Cp2U(SR)2 and Na[Cp*2U(StBu)(S)].
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