Tris-ureas as versatile and highly efficient organocatalysts for Michael addition reactions of nitro-olefins: Mechanistic insight from in-situ diagnostics
摘要:
Tris(2-aminoethyl)-amine, TREN based tris-ureas (1a-1d) and tris-thiourea (1e) have been explored towards a wide range of catalytic Michael addition reactions. These tris-ureas, 1a-1d efficiently catalyze the addition reaction of beta-nitro styrenes (2a-2d) with various nucleophiles such as beta-ketoesters (3a-3c), 1,3-dicarbonyl compound (3d), a cyanoester (3e) and a nitroester (3f) under ambient conditions to produce corresponding nitro alkanes in high yields. Pentafluorophenyl attached tris-urea, 1d is found to be the most effective catalyst in the series that yields 78-98% products conversion. In case of the reaction between beta-nitro styrenes and malononitrile (3g) in presence of 1d, 2-amino-5-nitro-4,6-diphenylcyclohex-1-ene-1,3,3-tricarbonitriles are also isolated as a minor product along with the corresponding Michael adduct. The added advantage of bridge-head nitrogen center in tris-urea organocatalysts, 1a-1d has been established by studying analogous benzene platform based tris-ureas (1f, 1g, 1h) in similar experimental conditions. Furthermore, a plausible reaction mechanism has also been established based on in-situ H-1 NMR kinetic studies. (C) 2015 Elsevier B.V. All rights reserved.
The cytotrophoblast (CTB) cells of the human placenta have membrane receptors that bind certain cardiotonic steroids (CTS) found in blood plasma. One of these, marinobufagenin, is a key factor in the etiology of preeclampsia. Herein, we used synthetic receptors (SR) to study their effectiveness on the angiogenic profile of human first trimester CTB cells. The humanextravillous CTB cells (Sw.71) used in this study were derived from first trimester chorionic villus tissue. Culture media of CTB cells treated with ≥1 nM SR level revealed sFlt-1 (Soluble fms-like tyrosine kinase-1) was significantly increased while VEGF (vascular endothelial growth factor) was significantly decreased in the culture media (* p < 0.05 for each) The AT2 receptor (Angiotensin II receptor type 2) expression was significantly upregulated in ≥1 nM SR-treated CTB cells as compared to basal; however, the AT1 (Angiotensin II receptor, type 1) and VEGFR-1 (vascular endothelial growth factor receptor 1) receptor expression was significantly downregulated (* p < 0.05 for each). Our results show that the anti-proliferative and anti-angiogenic effects of SR on CTB cells are similar to the effects of CTS. The observed anti angiogenic activity of SR on CTB cells demonstrates that the functionalized-urea/thiourea molecules may be useful as potent inhibitors to prevent CTS-induced impairment of CTB cells.
人类胎盘的细胞滋养层细胞(CTB)具有膜受体,这些受体能结合血浆中发现的某些强心类固醇(CTS)。其中一种称为金线蛙甾醇,是子痫前期发病机制中的关键因素。本文中,我们利用合成受体(SR)来研究它们对人类孕早期CTB细胞的血管生成特征的有效性。本研究所用的外滋养层人类CTB细胞(Sw.71)源自孕早期的绒毛组织。经≥1 nM SR水平处理的CTB细胞培养基显示出可溶性酪氨酸激酶受体Fms样1(sFlt-1)显著增加,而血管内皮生长因子(VEGF)显著减少(* p < 0.05)。与基础水平相比,≥1 nM SR处理的CTB细胞中,血管紧张素II受体2型(AT2)表达显著上调;而血管紧张素II受体1型(AT1)和血管内皮生长因子受体1(VEGFR-1)的表达则显著下调(* p < 0.05)。我们的结果表明,SR对CTB细胞的抗增殖和抗血管生成作用与CTS的作用相似。SR在CTB细胞上展现的抗血管生成活性表明,功能化的脲/硫脲分子可能作为强效抑制剂,用以预防CTS诱导的CTB细胞功能障碍。
Trapped inorganic phosphate dimer
作者:P. S. Lakshminarayanan、I. Ravikumar、E. Suresh、Pradyut Ghosh
DOI:10.1039/b713365k
日期:——
Single crystal X-ray crystallographic signature of the pentafluorophenyl substituted tripodal urea-based receptor shows formation of a pseudo dimeric cage which also encapsulates a phosphate dimer via numerous hydrogen bonding and anion⋯π interactions.
Structure–Activity Relationships in Tripodal Transmembrane Anion Transporters: The Effect of Fluorination
作者:Nathalie Busschaert、Marco Wenzel、Mark E. Light、Paulina Iglesias-Hernández、Ricardo Pérez-Tomás、Philip A. Gale
DOI:10.1021/ja205884y
日期:2011.9.7
this class of compound is capable of transporting chloride through a lipid bilayer via a variety of mechanisms, including chloride/H+ cotransport and chloride/nitrate, chloride/bicarbonate, and to a lesser extent an unusual chloride/sulfate antiport process. Calculations indicate that increasing the degree of fluorination of the tripodal transmembrane transporters increases the lipophilicity of the transporter
制备了一系列易于制备的含有脲和硫脲基团的氟化三足阴离子转运蛋白,并研究了它们的阴离子转运特性。使用离子选择性电极的囊泡阴离子转运测定表明,此类化合物能够通过多种机制转运氯离子通过脂质双层,包括氯离子/H+共转运和氯离子/硝酸盐、氯离子/碳酸氢盐,并且在较小程度上不寻常的氯化物/硫酸盐反向转运过程。计算表明,增加三足跨膜转运蛋白的氟化程度会增加转运蛋白的亲脂性,这被证明是氟化化合物优异转运活性的主要影响因素,clog P = 8 时实现了最大转运速率最活跃的转运蛋白5含有附加有3,5-双(三氟甲基)苯基的尿素官能团,并且能够在受体与脂质比率低至1:250000时介导跨膜氯化物转运。质子核磁共振滴定和单晶 X 射线衍射揭示了三足受体在溶液和固态中以 1:1 或 2:1 化学计量以不同亲和力结合不同阴离子的能力。我们还提供证据表明,通过使用一系列体外活力和荧光测定,最有效的阴离子转运蛋白能够诱导人类癌细胞凋亡。
Aerial CO
<sub>2</sub>
Trapped as CO
<sub>3</sub>
<sup>2–</sup>
Ions in a Dimeric Capsule That Efficiently Extracts Chromate, Sulfate, and Thiosulfate from Water by Anion‐Exchange Metathesis
carbonate capsule and are 9.70 A for [(L1) 2 ·(CrO 4 )·(TBA) 2 ] (2), 9.61 A for [(L1) 2 ·(S 2 O 3 )·(TBA) 2 ] (3), and 9.71 A for [(L1) 2 ·(SO 4 )·(TBA) 2 ] (4). Quantification by weighing the bulk extract shows that 1 can separately extract ca. 90 % of the above three anionsfromwater by anion-exchange metathesis. The quantitative estimations of the extractions of SO 4 2– and CrO 4 2–ions were further
三(2-氨基乙基)胺基(tren基)3-氰基苯基取代的三足尿素L1是熟悉的尿素基阴离子受体之一,已显示出将CO 3 2– 离子封装为碳酸盐胶囊[(L1 ) 2 ·(CO 3 )·(TBA) 2 ] (1, TBA = 四丁基铵) 通过从碱性二甲基亚砜 (DMSO) 溶液中固定空气中的二氧化碳。单晶 X 射线结构分析证实了 CO 3 2- 离子通过形成十二个强 N-H…O 氢键相互作用在 L1 (9.62 A) 的二聚体囊状组件的腔中包裹。1 的优异 CHCl 3 和 CH 2 Cl 2 溶解度已被用于通过阴离子-从水中提取 CrO 4 2- 、SO 4 2- 和 S 2 O 3 2- 离子的液-液(L-L)萃取。交换复分解。1 H NMR 光谱明确证实了从水中提取这些阴离子,红外光谱、粉末 XRD (PXRD) 和单晶 X 射线衍射分析。大量提取物的 1 H NMR 光谱分析支持形成 2:1(主客体)复合物。对于
Neutral tripodal receptors towards efficient trapping of oxalate
Tris(2-aminoethyl)amine (TREN) based pentafluorophenyl urea and 4-cyanophenyl thiourea receptors have shown encapsulation of oxalate ( $\mathrm C}_2}}\mathrm O}_4}}^2-}})$ in semi-aqueous environment. A single crystal X-ray study shows trapping of planar conformer of $\mathrm C}_2}}\mathrm O}_4}}^2-}}$ in both the cases. Further solution state binding of $\mathrm C}_2}}\mathrm O}_4}}^2-}}$ is probed by 1H-NMR titration study in semi-aqueous solvent.