Refernces
10.1021/jm040780c
The research focuses on the design, synthesis, stability, and biological investigation of dipeptidomimetic ketomethylene isosteres as pro-moieties for drug transport via the human intestinal di-/tripeptide transporter hPEPT1. The study involves the synthesis of five model prodrugs containing ketomethylene amide bond replacements, which were derived from readily available R,-unsaturated γ-ketoesters, with the model drug (BnOH) attached to various positions of the dipeptidomimetic. The experiments conducted include assessing the chemical stability of these prodrugs at different pH levels, their affinity for hPEPT1, and their transepithelial transport properties using Caco-2 cell monolayers. The reactants used in the synthesis involve R,-unsaturated γ-ketoesters, benzyl alcohol, and various amino acid derivatives, with analyses performed using techniques like HPLC, NMR, and UV detection to assess stability, affinity, and transport kinetics. The research aims to identify promising pro-moieties for a prodrug approach targeting hPEPT1, with the goal of enhancing oral bioavailability of drugs.
10.1055/s-0029-1217335
The study presents a novel and highly chemoselective method for the acetylation of alcohols using ethyl acetate as the acetyl donor, catalyzed by a tetranuclear zinc cluster (Zn4(OCOCF3)6O). The main focus of the research was to develop a green chemistry approach that efficiently converts alcohols into their corresponding acetates under mild reaction conditions with minimal waste production. The researchers utilized various functionalized alcohols as substrates, including benzyl alcohols with different para-substituents, primary aliphatic alcohols, and secondary alcohols, to demonstrate the broad applicability and functional-group compatibility of the method. The purpose of using the tetranuclear zinc cluster catalyst was to achieve high chemoselectivity, even in the presence of highly nucleophilic aliphatic amino groups, approaching the selectivity of enzymatic systems. The study also highlighted the ability to selectively acetylate aliphatic hydroxyl groups in the presence of phenolic groups, showcasing the potential of this method in complex molecule synthesis. The use of ethyl acetate as both the acetyl donor and solvent provided economic and environmental benefits, as it is stable, accessible, and resulted in minimal byproducts. The study's findings suggest that this catalytic system could be a valuable tool for environmentally benign acetylation reactions in organic synthesis.
10.1007/s12039-019-1682-x
The study focuses on the design and synthesis of sulfur-containing butylated hydroxytoluene (S-BHT) derivatives, which are multipotent antioxidants (MPAOs). These compounds were evaluated for their antioxidant potency and their potential as selective anticancer agents against human cancer cell lines HT29 (colon cancer) and MCF7 (breast cancer). The chemicals used in the study include BHT, various thiols, and p-toluenesulfonic acid (PTSA) as a catalyst. The purpose of these chemicals was to synthesize a series of S-BHT derivatives, which were then tested for their inhibitory activities against free radicals and their cytotoxic effects on the specified cancer cell lines. The study aimed to develop new antioxidants with enhanced radical scavenging abilities and to explore their potential as effective and selective anticancer agents.
10.1016/0008-6215(83)88254-8
This research aims to develop a convenient and practical method for synthesizing complex saccharides that are part of glycoconjugates. The study focuses on synthesizing a key intermediate compound for the production of a specific carbohydrate structure found in blood-group substances. The researchers used various chemicals, including benzyl alcohol, mercuric cyanide, hexamethyl-disilazane, chlorotrimethylsilane, acetic anhydride, and 2,2-dimethoxypropane, among others, to achieve the desired synthesis. The process involved multiple steps of acetylation, deacetylation, silylation, and isopropylidenation. The final product was obtained in good yields and its structure was confirmed through NMR spectroscopy. The study concludes that the synthesized intermediate could be a suitable precursor for the further synthesis of more complex oligosaccharides, potentially useful in the study of glycosidases, glycosyltransferases, and as synthetic antigens.
10.1016/S0040-4039(00)96022-2
The study investigates the thermal decomposition of 3-benzyloxy-3-chlorodiazirine in acetonitrile at 25°C to produce benzyloxychlorocarbene, which further fragments to form the benzyl cation. The researchers conducted a detailed analysis of the reaction, examining the effects of different solvents and solvent conditions on the fragmentation process. They found that the reaction proceeded cleanly in acetonitrile, with only minor solvent effects on the rate constant. The study also included an Arrhenius study to determine the energy of activation and a Hammett study to understand the reaction's sensitivity to substituent effects. The researchers proposed that the thermal fragmentation of benzyloxychlorocarbene yields intermediates such as ion pairs and suggested that the geometry of the diazirine prior to decomposition may influence the distribution of these ion pairs. Additionally, they explored the photolytic decomposition of the compound and observed the formation of benzyl radical, although they concluded that this was not the principal pathway for the fragmentation of the carbene. The study was supported by the National Science Foundation and contributed to the understanding of carbene chemistry and the formation of carbocations.
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/ol202582c
The study presents an efficient method for the N-alkylation of sulfonamides and amines using alcohols as alkylating reagents, catalyzed by manganese dioxide (MnO2) under aerobic and solvent-free conditions. This approach is a greener alternative to traditional methods, as it avoids the use of noble metal catalysts, preformed complexes, and inert atmosphere protection. The researchers found that MnO2 is a less toxic, readily available, and recyclable catalyst that can facilitate the reaction at mild temperatures without the need for high pressure or large excess amounts of reagents. The method was successfully applied to a variety of sulfonamides and amines, yielding good to high product yields. Additionally, the study explores the potential mechanism of the reaction, suggesting a process involving Mn-mediated alcohol oxidation, condensation, transfer hydrogenation, and regeneration of the aldehyde, which completes the catalytic cycle. The developed method simplifies operation and workup procedures and may serve as a promising alternative to existing N-alkylation methods.
10.1021/ja003851f
This research study on the polymerization of lactide using zinc and magnesium β-diiminate complexes, with a focus on stereocontrol and mechanism. The purpose of the study was to develop single-site metal catalysts capable of controlling the stereochemistry of poly(lactic acid) (PLA), a biodegradable polymer with potential applications in medical, agricultural, and packaging fields. The researchers synthesized a series of zinc(II) and magnesium(II) alkoxides based on a β-diiminate ligand framework and found that [(BDI-1)ZnOiPr]2 exhibited the highest activity and stereoselectivity among the zinc complexes studied. This complex was able to polymerize rac- and meso-lactide to PLA with high control over the stereochemistry, resulting in isotactic, heterotactic, and syndiotactic PLA microstructures. The polymerizations were found to be living, as evidenced by narrow polydispersities and linear relationships between number average molecular weight and conversion plots. The study concluded that the substituents on the β-diiminate ligand significantly influenced the stereoselectivity and polymerization rate.
10.1021/jo00048a029
The research focuses on the formal [3 + 2] cycloaddition of benzylic cations with alkenes, specifically styrenes, to afford dihydro(1H)indenes in good yield. The purpose of this study was to develop a general and stereoselective method for the preparation of highly substituted dihydro(1H)indenes, which are significant due to their presence in many natural products and synthetic compounds with biological activity. The researchers utilized benzylic cations generated from quinone methides and benzylic alcohols to react with styrenes, demonstrating remarkable stereoselectivity, particularly with (E)-styrenes, resulting in dihydro(1H)indenes with three stereogenic centers with >40:1 diastereoselectivity.
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