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101.
Lydia Kronsjö 《BIT Numerical Mathematics》1975,15(1):107-110
102.
103.
Enantioselective Organocatalytic Cascade Approach to Different Classes of Benzofused Acetals 下载免费PDF全文
Bruno Matos Paz Dr. Lydia Klier Line Næsborg Vibeke Henriette Lauridsen Prof. Dr. Frank Jensen Prof. Dr. Karl Anker Jørgensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16810-16818
A novel enantioselective organocatalytic strategy is presented for the synthesis of tetrahydrofurobenzofuran and methanobenzodioxepine natural product core structures. The strategy is based on a pair of divergent reaction pathways in which hydroxyarenes react with γ‐keto‐α,β‐unsaturated aldehydes, catalyzed by a chiral secondary amine. One reaction pathway, which leads to chiral 5,5‐fused acetals with two stereocenters—the tetrahydrofurobenzofuran scaffolds—proceeds in moderate yields and up to 96 % ee. The other reaction pathway provides 5,6‐bridged methanobenzodioxepine scaffolds with three stereocenters in moderate to good yields and up to 95 % ee. The reaction is remarkable as it can proceed with catalyst loadings as low as 0.25 mol %, providing one of the highest known turnover numbers in iminium ion catalysis. Furthermore, the hemiacetal tetrahydrofurobenzofuran can undergo functionalizations including reduction, oxidation, and allylation. Finally, the effects involved in the substrate control for the divergent pathways, based on both experimental and computational studies, have been investigated. A model involving steric, electronic and stereoelectronic interactions is discussed to rationalize the observed selectivities. 相似文献
104.
105.
Synthesis of Pyrrolo[2,3‐d]pyrimidines by Copper‐Mediated Carbomagnesiations of N‐Sulfonyl Ynamides and Application to the Preparation of Rigidin A and a 7‐Azaserotonin Derivative 下载免费PDF全文
Johannes Nickel Dr. Maitane Fernández Dr. Lydia Klier Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14397-14400
The treatment of readily available N‐alkynyl‐5‐iodo‐6‐sulfamido‐pyrimidines with iPrMgCl?LiCl followed by a transmetalation with CuCN?2 LiCl produces, after intramolecular carbocupration, metalated py r rolo[2,3‐d]pyrimidines. Quenching of these pyrimidines with allylic halides or acid chlorides results in polyfunctional pyrrolo[2,3‐d]pyrimidines. Further reaction with ICl and a Negishi cross‐coupling, using PEPPSI‐iPr as the catalyst, furnishes fully substituted N‐heterocycles. A formal synthesis of the marine alkaloid rigidin A has been achieved as well as the preparation of a derivative of 7‐azaserotonine, related to the natural hormone serotonin. 相似文献
106.
107.
Lydia KerschensteinerFlorian Löbermann Wolfgang Steglich Dirk Trauner 《Tetrahedron》2011,67(8):1536-1539
Crocipodin, an unusual benzotropolone pigment, has been isolated from the fruit bodies of the mushroom Leccinum crocipodium. Its structure was determined by spectroscopic methods, particularly 2D NMR spectroscopy. The structure was confirmed by total synthesis, starting from 4-bromocatechol and gallic acid. 相似文献
108.
Manuel Sánchez-Cantú Lydia M. Pérez-Díaz Efraín Rubio-Rosas Victor H. Abril-Sandoval Jorge G. Merino-Aguirre Federico M. Reyes-Cruz Laura Orea 《Chemical Papers》2014,68(5):638-649
A series of MgZnAl hydrotalcite-like compounds with different zinc content (1–25 mass % of nominal zinc content) were prepared by a simple and environmentally-friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG), nitrogen adsorption-desorption at ?196°C (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and CO2 temperature-programmed desorption (CO2-TPD). Transesterification of castor oil with methanol was selected as a probe reaction to stress the effect of zinc incorporation. From the XRD analysis of fresh samples it was demonstrated that the incorporation of zinc is feasible in the nominal range of 1–10 mass % while in the samples with higher zinc content, zinc nitrate and ZnO as secondary crystalline phases were observed. Furthermore, the analysis of samples calcined at 450°C indicated the coexistence of the ZnO and MgO crystalline phases. From the EDS and TG characterizations, the zinc percentage and thermal decomposition of the samples were determined. It was revealed that the samples exhibited the characteristic platy-like habit of hydrotalcite-like compounds. The BET analysis confirmed that the calcined samples presented an increment in their specific surface area values compared with the pristine ones. It was established that the amount of basic sites diminished with the zinc incorporation, which also affected the conversion degree of the transesterification reaction. 相似文献
109.
Ramona Samba Kai Fuchsberger Ilona Matiychyn Sebastian Epple Lydia Kiesel Alfred Stett Wolfgang Schuhmann Martin Stelzle 《Electroanalysis》2014,26(3):548-555
In this work, composite microelectrodes from poly(3,4‐ethylenedioxythiophene) (PEDOT) and carbon nanotubes (CNT) are characterized as electrochemical sensing material for neurotransmitters. Dopamine can be detected using square wave voltammetry at these microelectrodes. The CNTs improve the sensitivity by a factor of two. In addition, the selectivity towards dopamine in the presence of ascorbic acid and uric acid was examined. While both electrodes, PEDOT and PEDOT‐CNT are able to detect all measured concentrations of dopamine in the presence of uric acid, small concentrations of dopamine and ascorbic acid are only distinguishable at PEDOT‐CNT electrodes. Changing the pH has a strong influence on the selectivity. Moreover, it is possible to detect concentrations as low as 1 µM dopamine in complex cell culture medium. Finally, other catecholamines like serotonin, epinephrine, norepinephrine and L ‐dopa are also electrochemically detectable at PEDOT‐CNT microelectrodes. 相似文献
110.
Maria Cristina Marcucci Carlos Rocha Oliveira Daniel Spindola Alyne A. Antunes Leila Y. K. Santana Victor Cavalaro Isabelle B. Costa Ana C. de Carvalho Thiago A. M. Veiga Livia S. Medeiros Lucas dos Santos Zamarioli Carolina P. Gonalves Milena F. Santos Simone S. Grecco Vanessa Y. Suzuki Lydia Masako Ferreira Daniel M. Garcia 《Molecules (Basel, Switzerland)》2022,27(17)
The aim of this study was to investigate the cytotoxic activity of the Coriandrum sativum (C. sativum) ethanolic extract (CSEE) in neuroblastoma cells, chemically characterize the compounds present in the CSEE, and predict the molecular interactions and properties of ADME. Thus, after obtaining the CSEE and performing its chemical characterization through dereplication methods using UPLC/DAD-ESI/HRMS/MS, PM6 methods and the SwissADME drug design platform were used in order to predict molecular interactions and ADME properties. The CSEE was tested for 24 h in neuroblastoma cells to the establishment of the IC50 dose. Then, the cell death was evaluated, using annexin-PI, as well as the activity of the effector caspase 3, and the protein and mRNA levels of Bax and Bcl-2 were analyzed by ELISA and RT-PCR, respectively. By UHPLC/DAD/HRMS-MS/MS analysis, the CSEE showed a high content of isocoumarins-dihydrocoriandrin, coriandrin, and coriandrones A and B, as well as nitrogenated compounds (adenine, adenosine, and tryptophan). Flavonoids (apigenin, hyperoside, and rutin), phospholipids (PAF C-16 and LysoPC (16:0)), and acylglicerol were also identified in lower amount as important compounds with antioxidant activity. The in silico approach results showed that the compounds 1 to 6, which are found mostly in the C. sativum extract, obey the “Five Rules” of Lipinski, suggesting a good pharmacokinetic activity of these compounds when administered orally. The IC50 dose of CSEE (20 µg/mL) inhibited cell proliferation and promoted cell death by the accumulation of cleaved caspase-3 and the externalization of phosphatidylserine. Furthermore, CSEE decreased Bcl-2 and increased Bax, both protein and mRNA levels, suggesting an apoptotic mechanism. CSEE presents cytotoxic effects, promoting cell death. In addition to the promising results predicted through the in silico approach for all compounds, the compound 6 showed the best results in relation to stability due to its GAP value. 相似文献