Totally found 269 items.

  • [期刊] Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated beta-carboxymethyl O and S-glycosides
    Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of beta-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent beta-lactams and other bioactive molecules of diverse medicinal interest.
  • [期刊] Microwave-assisted Amination Reactions: An Overview
    C-N coupling reactions were found to be attractive among researchers owing to the importance of C-N bond formation in heterocyclic synthesis. Hence C-N bond formation via amination reaction with the assistance of microwave radiations gained significant attraction recently. Microwave-assisted reactions are greener, faster and generally efficient compared to the conventional thermal reactions offering better purity of the product with enhancement in the yield. It was surprisingly revealed that several new advancements in amination reactions were highly influenced by this greener technology. This first review on microwave-assisted amination reaction focuses on the novel amination strategies that emerged with the help of microwave methodology, and covers literature up to 2019.
  • [期刊] The Synthesis of New Selenium-containing Heterocycles by the Oxidation Reaction of 2,4-Diaryltetrahydro-4H-selenochromenes
    We have explored the reactions of tetrahydro-4H-selenochromenes in the presence of phosphoric pentachloride, and synthesized new condensate aroylbenzoselenophenes. During the reactions, tetrahydro-4H-selenochromenes with phosphoric pentachloride underwent oxidative aromatization and nucleophilic substitution for a chlorine atom of one of the protons in the alicyclic fragment. Also, the narrowing of the heterocyclic fragment occurred as in synthesized selenium-containing compounds earlier transformed into the corresponding condensate aroylbenzoselenophenes.
  • [期刊] Amano Lipase PS from Burkholderia cepacia - Evaluation of the Effect of Substrates and Reaction Media on the Catalytic Activity
    Lipases in the native or immobilized form have commonly been used as catalysts in the chemical and pharmaceutical industry. One of the widely available enzyme catalysts on the market is lipase from Burkholderia cepacia (BCLs), previously called Pseudomonas cepacia (PCLs). This enzyme is applied, among others, in the stereoselective acylation of molecules to achieve chiral pure enantiomers of drugs or their building blocks. In this study, Amano lipase PS (APS-BCL), which is a commercial lipase from Burkholderia cepacia (BC) was tested. The lipolytic activity of APS-BCL by hydrolysis of vegetable oils and enantioselective activity of APS-BCL by the kinetic resolution of (R,S)-1-phenylethanol with using isopropenyl acetate as an acyl donor were evaluated. An effect of reaction media with different logP values (t-butyl methyl ether, dichloromethane, diisopmpyl ether, toluene, cyclohexane, n-hexane, isooctane and n-heptane) on the enantioselective activity of lipase was also studied. The high value of the enantiomeric ratio (E =308.5) with the utilization of isopropenyl acetate was achieved. Whereas, the best reaction medium turned out to be diisopmpyl ether, C =47.9%, ee(p) =98%, ee, =90%, after 24 h of incubation. Moreover, the influence of omega 6/omega 9 polyunsaturated fatty acids (PU-FM) ratio in commercial (peanut, camelina, rape, pumpkin seed, walnut, sesame, avocado, rice, corn, black cumin, hemp, safflower, grape seed) oils was investigated for the lipase activity. For the first time, the cut-off limit of omega 6/omega 9 ratio was proposed. The ratio equal to or higher than 2.3 allows achieving higher lipolytic activity.
  • [期刊] Temporary Solubilizing Tags Method for the Chemical Synthesis of Hydrophobic Proteins
    Hydrophobic proteins, as one of the cellular protein classifications, play an essential function in maintaining the normal life cycle of living cells. Researches on the structure and function of hydrophobic proteins promote the exploration of the causes of major diseases, and development of new therapeutic agents for disease treatment. However, the poor water solubility of hydrophobic proteins creates problems for their preparation, separation, characterization and functional studies. The temporary solubilizing tags are considered a practical strategy to effectively solve the poor water solubility problem of hydrophobic proteins. This strategy can significantly improve the water solubility of hydrophobic peptides/proteins, making them like water-soluble peptides/proteins easy to be purified, characterized. More importantly, the temporary solubilizing tags can be removed after protein synthesis, so thus the structure and function of the hydrophobic proteins are not affected. At present, temporary solubilizing tags have been successfully used to prepare many important hydrophobic proteins such as membrane proteins, lipoproteins and chaperones. In this review, we summarize the recent researches and applications of temporary solubilizing tags.
  • [期刊] Synthesis of Heterocyclic Triterpene Derivatives with Biological Activities via Click Reaction
    Grignard reactions were applied to synthesize 2-ethynyl-2-hydroxylallobetulin 5 from 2-oxoallobetulin 4. The compound plays an important role as starting material to synthesize heterocyclic triterpenes using the click reaction. A series of new 1,2,3-triazole derivatives derived from 2-oxoallobetulin were successfully obtained. Under similar reaction conditions, only one compound 6 kept the hydroxyl functional group, while in the other compounds 7, 8 and 9, water was eliminated. The structures of obtained compounds were confirmed by 2D-NMR spectroscopy. The X-ray analysis of 5 indicated that only one isomer was obtained and in this compound, the hydroxyl group is situated on the same side as the ether group, the ethynyl group being situated at the opposite side. All products were also evaluated for their cytostatic activity in cell culture including L1210, CEM and Hela. Several compounds showed measurable cytostatic activity in the micromolar range.
  • [期刊] Transitiona-metal Nanoparticles Catalyzed Carbon-Carbon Coupling Reactions in Water
    The use of transition-metal nanoparticles in catalysis has attracted much interest, and their use in carbon-carbon coupling reactions such as Suzuki, Heck, Sonogashira, Stille, Hiyama, and Ullmann coupling reactions constitutes one of their most important applications. The transition-metal nanoparticles are considered as one of the green catalysts because they show high catalytic activity for several reactions in water. This review is devoted to the catalytic system developed in the past 10 years in transition-metal nanoparticles-catalyzed carbon-carbon coupling reactions such as Suzuki, Heck, Sonogashira, Stine. Hiyama, and Ullmann coupling reactions in water.
  • [期刊] Ionic Liquids: A Versatile Medium for the Synthesis of Six-membered Two Nitrogen-Containing Heterocycles
    Due to special properties of ILs (ionic liquids) like their wide liquid range, good solvating ability, negligible vapour pressure, non-inflammability, environment-friendly medium, high thermal stability, easy recycling and rate promoters etc. they are used in organic synthesis. Therefore, ionic liquids have attracted the attention of chemists and act as a catalyst and reaction medium in organic reaction with high activity. There is no doubt that ionic liquids have become a major subject of study for modern chemistry. More publications in the field have been observed each year, although there is some evidence that this is beginning to plateau at approximately 3500 papers each year. They have been the subject of several major reviews and books, dealing with different applications and aspects of their behavior. Highly efficient methods are explored for the preparation of six-membered two nitrogen-containing heterocycles with the application of IL as a catalyst and reaction medium from 1893 to 2018.
  • [期刊] An Overview of the Chemistry and Pharmacological Potentials of Furanones Skeletons
    The furanone structure, a significant group of heterocyclic compounds, is frequently found in natural products that are exhibiting striking pharmacological effects and a growing field of research. They have a wide spectrum of pharmaceutical activity: anticataract, anticancer, antibacterial, anti-inflammatory, anticonvulsant. This review article presents a summary of natural furanones, synthetic methods, and the biological effects of these important compounds. Solid-phase method, cross-coupling reactions, Maillard-type reaction, the cycloaddition of alcohol and phenyl nitrile oxide, and side-chain modifications are some types of reactions for the preparation of furanone derivatives. Methods of preparation and pharmacological activities of furanone skeletons that are discussed in this review article will help the medicinal chemists to design and execute novel procedures towards finding new drugs.
  • [期刊] Pyrazolo[1,5-a]pyrimidines: A Close Look into their Synthesis and Applications
    Pyrazolo[1,5-a]pyrimidines are fused N-heterocyclic systems of a pyrazole. They are considered as a key structural motif in many vital applications, such as medicinal, pharmaceuticals, pesticides, dyes and pigments. Their synthetic routes have escalated dramatically in the last decades. The current review is a recent synthetic survey of pyrazolo[1,5-a]pyrimidines and their applications until recently.