Search results for "Cyclobutanes"
showing 10 items of 12 documents
A novel moniliformin derivative as pan-inhibitor of histone deacetylases triggering apoptosis of leukemia cells
2021
New and potent agents that evade multidrug resistance (MDR) and inhibit epigenetic modifications are of great interest in cancer drug development. Here, we describe that a moniliformin derivative (IUPAC name: 3-(naphthalen-2-ylsulfanyl)-4-{[(2Z)-1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene]methyl}cyclobut-3-ene-1,2-dione; code: MCC1381) bypasses P-gp-mediated MDR. Using transcriptomics, we identified a large number of genes significantly regulated in response to MCC1381, which affected the cell cycle and disturbed cellular death and survival. The potential targets of MCC1381 might be histone deacetylases (HDACs) as predicted by SwissTargetPrediction. In silico studies confirmed that MCC13…
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
2010
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…
Gold(I)-Catalyzed Intermolecular Cycloaddition of Allenamides with α,β-Unsaturated Hydrazones: Efficient Access to Highly Substituted Cyclobutanes
2014
α,β-Unsaturated N,N-dialkyl hydrazones undergo a mild [2 + 2] cycloaddition to allenamides when treated with a suitable gold catalyst. The method, which represents the first application of N,N-dialkyl hydrazones in gold catalysis, is compatible with a wide variety of substituents at the alkenyl moiety of the hydrazone component, proceeds with excellent levels of regio- and diastereoselectivity, and provides densely substituted cyclobutanes with good to excellent yields.
Counterintuitive Mechanisms of the Addition of Hydrogen and Simple Olefins to Heavy Group 13 Alkene Analogues
2013
The mechanism of the reaction of olefins and hydrogen with dimetallenes ArMMAr (Ar = aromatic group; M = Al or Ga) was studied by density functional theory calculations and experimental methods. The digallenes, for which the most experimental data are available, are extensively dissociated to gallanediyl monomers, :GaAr, in hydrocarbon solution, but the calculations and experimental data showed also that they react with simple olefins, such as ethylene, as intact ArGaGaAr dimers via stepwise [2 + 2 + 2] cycloadditions due to their considerably lower activation barriers vis-à-vis the gallanediyl monomers, :GaAr. This pathway was preferred over the [2 + 2] cycloaddition of olefin to monomeric…
Squaramide-based reagent for selective chromogenic sensing of Cu(II) through a zwitterion radical.
2010
A minimalist squaramide-based chemodosimeter for Cu(2+) is described. Upon selective chelation to 2, Cu(2+) induces the formation of a highly colored zwitterionic radical, which is kinetically stable for hours. The presence of a radical is confirmed by EPR and ESI-MS. It is then possible to use reagent 2 for visual and selective sensing of Cu(2+) at neutral pH.
Squaric Acid Mediated Synthesis and Biological Activity of a Library of Linear and Hyperbranched Poly(Glycerol)-Protein Conjugates
2012
Polymer-protein conjugates generated from side chain functional synthetic polymers are attractive because they can be easily further modified with, for example, labeling groups or targeting ligands. The residue specific modification of proteins with side chain functional synthetic polymers using the traditional coupling strategies may be compromised due to the nonorthogonality of the side-chain and chain-end functional groups of the synthetic polymer, which may lead to side reactions. This study explores the feasibility of the squaric acid diethyl ester mediated coupling as an amine selective, hydroxyl tolerant, and hydrolysis insensitive route for the preparation of side-chain functional, …
Squaric acid mediated chemoselective PEGylation of proteins: reactivity of single-step-activated α-amino poly(ethylene glycol)s.
2012
The covalent attachment of poly(ethylene glycol) (PEG) to therapeutically active proteins (PEGylation) has become an important method to deal with the pharmacological difficulties of these polypeptides, such as short body-residence times and immunogenicity. However, the derivatives of PEG used for PEGylation lack further functional groups that would allow the addition of targeting or labeling moieties. Squaric acid diethyl ester was used for the chemoselective single-step activation of poly(ethylene glycol)s into the respective ester amides. The resultant selective protein-reactive poly(ethylene glycol)s were investigated with respect to their selectivity towards amino acid residues in bovi…
Squaraine Dyes for Photodynamic Therapy: Study of Their Cytotoxicity and Genotoxicity in Bacteria and Mammalian Cells¶‡
2007
Halogenated squaraine dyes are characterized by long wavelength absorption (>600 nm) and high triplet yields and therefore represent new types of photosensitizers that could be useful for photodynamic therapy. We have analyzed the cytotoxicity and genotoxicity of the bromo derivative 1, the iodo derivative 2 and the corresponding nonhalogenated dye 3 in the absence and presence of visible light. At concentrations of 1-2 microM, 1 and 2 reduced the cloning efficiency of AS52 Chinese hamster ovary cells to less than 1% under conditions that were well tolerated in the dark. Similarly, the proliferation of L5178Y mouse lymphoma cells was inhibited by photoexcited 1 and 2 with high selectivity. …
Near Infrared Spectroscopy Detection and Quantification of Herbal Medicines Adulterated with Sibutramine.
2015
There is an increasing demand for herbal medicines in weight loss treatment. Some synthetic chemicals, such as sibutramine (SB), have been detected as adulterants in herbal formulations. In this study, two strategies using near infrared (NIR) spectroscopy have been developed to evaluate potential adulteration of herbal medicines with SB: a qualitative screening approach and a quantitative methodology based on multivariate calibration. Samples were composed by products commercialized as herbal medicines, as well as by laboratory adulterated samples. Spectra were obtained in the range of 14,000-4000 per cm. Using PLS-DA, a correct classification of 100% was achieved for the external validatio…
ChemInform Abstract: Gold(I)-Catalyzed Intermolecular Cycloaddition of Allenamides with α,β-Unsaturated Hydrazones: Efficient Access to Highly Substi…
2015
α,β-Unsaturated N,N-dialkyl hydrazones undergo a mild [2 + 2] cycloaddition to allenamides when treated with a suitable gold catalyst. The method, which represents the first application of N,N-dialkyl hydrazones in gold catalysis, is compatible with a wide variety of substituents at the alkenyl moiety of the hydrazone component, proceeds with excellent levels of regio- and diastereoselectivity, and provides densely substituted cyclobutanes with good to excellent yields.