Search results for "Amide"
showing 10 items of 3119 documents
(E)-2-Cyano-3-(5′-piperidin-1-yl-2,2′-bithien-5-yl)acrylic Acid: A Fluorescent Probe for Detecting Prefibrillar Oligomers
2013
The synthesis of (E)-2-cyano-3-(5′-piperidin-1-yl-2,2′-bithien-5-yl)acrylic acid, a novel amyloid aggregation fluorescent probe, is reported. This new probe is able to monitor soluble oligomeric aggregates after 24 h, at which time Thioflavin T emission, commonly used to monitor amyloid fibril formation, remains unchanged. Atomic force microscopy, native polyacrylamide gel electrophoresis, and dynamic light scattering confirm that the earlier stages of aggregation are prefibrillar oligomeric species not possessing the amyloid structure. This new molecular scaffold expands the toolbox of fluorescent probes for the identification of prefibrillar oligomers, which is needed in studies aimed at …
Optimisation of gradient elution with serially-coupled columns. Part I: single linear gradients.
2014
A mixture of compounds often cannot be resolved with a single chromatographic column, but the analysis can be successful using columns of different nature, serially combined through zero-dead volume junctions. In previous work (JCA 1281 (2013) 94), we developed an isocratic approach that optimised simultaneously the mobile phase composition, stationary phase nature and column length. In this work, we take the challenge of implementing optimal linear gradients for serial columns to decrease the analysis time for compounds covering a wide polarity range. For this purpose, five ACE columns of different selectivity (three C18 columns of different characteristics, a cyano and a phenyl column) we…
Adaptogens in chemobrain (Part II): Effect of plant extracts on chemotherapy-induced cytotoxicity in neuroglia cells
2019
Abstract Background Cancer chemotherapy-induced cognitive impairments are apparently associated with harmful effects on physiological functions of brain cells. Adaptogens, are known to exhibit neuroprotective effects and to increase cognitive functions in clinical studies. In our previous study (Seo et al., 2018), we demonstrated that selected adaptogenic extracts significantly attenuate cytostatic-induced regulation of more than 100 genes involved in the activation of neuronal death and inhibiting neurogenesis. Neuroprotective and cytoprotective activities of adaptogens rise the question about their possible impact on cytostatic effects of a chemotherapeutic combination of 5-fluorouracil, …
Cooperativity of H-bonding and anion–π interaction in the binding of anions with neutral π-acceptors
2012
A rare anion-π complex between bromide and a neutral receptor is reported and related receptor systems are studied with a series of anions. The interaction is observed in the solid state and in solution, and further evidence for it is obtained by a computational study.
New anionic cobalt complexes using highly hindered bis-amides with varying donor abilities as ligands.
2007
Four potential tetradentate ligands of formulae 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)ethane (H(4)L(1), 1), 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)propane (H(4)L(2), 2), 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)benzene (H(4)L(3), 3) and 1,8-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)naphthalene (H(4)L(4), 4) have been prepared and the crystal structures of three of them (1, 3 and 4) determined by single crystal X-ray diffraction. The investigation of their complexing ability toward Co(II) afforded the compounds of formulae [Co(III)(L(3))Na(I)(H(2)O)(2)] (5), [Co(III)(L(n))Li(I)(H(2)O)2] with n = 1 (6), 2 (7) and 3 (8) and [Co(II)(L(4))Li(I)(2)] (9). Complexes 5-8 are squa…
A bis(triazole)benzamide receptor for the complexation of halide anions and neutral carboxylic acid guests. Guest-controlled topicity and self-assemb…
2012
Bis(triazole)benzamide 1 has been readily synthesized by means of Cu-catalyzed 1,3-dipolar cycloaddition and its ability to bind halide anions and neutral gallic acid derivative 12GA has been theoretically and experimentally investigated. The cavity defined by the N-H amide group and the vicinal aromatic hydrogens is suitable to form H-bonding arrays with halide guests. The stability of complexes 1·Cl- and 1·Br- is very similar, as DFT calculations predict and 1H NMR titration experiments confirm. The zigzag "anti" conformation of the molecule generates two regions with complementary positive and negative potentials that favor the statistical complexation of two molecules of the neutral car…
Asymmetric Synthesis of Tetrahydrobenzofurans and Annulated Dihydropyrans via Cooperative One-Pot Organo- and Silver-Catalysis
2016
Synthesis : journal of synthetic organic chemistry 48(19), 3207-3216(2016). doi:10.1055/s-0035-1561468
1,2‐Benzothiazine Derivatives from Sulfonimidamides by Metal‐Catalyzed Annulation Reactions in Solution and under Solvent‐Free Mechanochemical Condit…
2021
Advanced synthesis & catalysis (2021). doi:10.1002/adsc.202001505 special issue: "Hot Topic: C-H Activation"
Biomimetic diels–alder cyclizations for the construction of the brevianamide, paraherquamide, sclerotamide, asperparaline and VM55599 ring systems
1998
Abstract A potentially bio-mimetic Diels–Alder cyclization to construct the bicyclo[2.2.2] ring system common to the paraherquamides, marcfortines, sclerotamides, brevianamides, VM55599, and asperparaline is reported. Epi-deoxybrevianamide E (22) is converted into the corresponding lactim ether (23) and then oxidized with DDQ to provide an azadiene (24) which is tautomerized in the presence of base to azadiene 25 which, spontaneously cyclizes to give a 2:1 mixture of cycloadducts 26 and 27. These cycloadducts are each in turn, converted into d , l -C-19-epi-brevianamide A (20) and d , l -brevianamide B (6). The stereochemical implications of the [4+2] cycloaddition is discussed in the conte…
Anthracene Fluorescence Quenching by a Tetrakis (Ketocarboxamide) Cavitand
2014
Quenching of both fluorescence lifetime and fluorescence intensity of anthracene was investigated in the presence of a newly derived tetrakis (ketocarboxamide) cavitand at various concentrations. Time-correlated single photon counting method was applied for the lifetime measurements. A clear correlation between the fluorescence lifetime of anthracene as a function of cavitand concentration in dimethylformamide solution was observed. The bimolecular collisional quenching constant was derived from the decrease of lifetime. Fluorescence intensity was measured in the emission wavelength region around 400 nm as a result of excitation at 280 nm. Effective quenching was observed in the presence of…