Search results for "DISCOVERY"
showing 10 items of 4119 documents
A DFT study of the Diels–Alder reaction between methyl acrolein derivatives and cyclopentadiene. Understanding the effects of Lewis acids catalysts b…
2006
Abstract The effects of Lewis acid catalysts based on sulfur containing boron heterocycles on the Diels–Alder reactions of two methyl acroleins with cyclopentadiene have been studied using DFT methods. These reactions take place along highly asynchronous concerted processes. While the reaction with crotonaldehyde leads to the expected endo adduct, the reaction with methacrolein leads to exo one in agreement with the experiments. The catalytic effect can be explained through the analysis of the electrophilicity index (ω) of the reagents, and the molecular structure of the corresponding transition structures.
Structure-activity relationship of dopaminergic halogenated 1-benzyl-tetrahydroisoquinoline derivatives
2009
Two series of halogenated 1-benzyl-7-chloro-6-hydroxy-tetrahydroisoquinolines were prepared to explore the influence of each series on the affinity for dopamine receptors. All the compounds displayed a high affinity for D(1)-like and/or D(2)-like dopamine receptors in striatal membranes, although they were unable to inhibit [(3)H]-dopamine uptake in striatal synaptosomes. The halogen placed on the benzylic ring in 1-benzyl-THIQs, compounds of the series 1, 2'-bromobenzyl derivatives with K(i) values into the nanomolar range, and the series 2, 2',4'-dichlorobenzyl-THIQ homologues, proves to be an important factor to modulate affinity at dopamine receptor. (C) 2009 Elsevier Masson SAS. All ri…
Iron Oxide/Hydroxide Nanoparticles with Negatively Charged Shells Show Increased Uptake in Caco-2 Cells
2012
The absorption of commonly used ferrous iron salts from intestinal segments at neutral to slightly alkaline pH is low, mainly because soluble ferrous iron is easily oxidized to poorly soluble ferric iron and because ferrous iron, but not ferric iron, is carried by the divalent metal transporter DMT-1. Moreover, ferrous iron frequently causes gastrointestinal side effects. Iron hydroxide nanoparticles with neutral and hydrophilic carbohydrate shells are alternatively used to ferrous salts. In these formulations gastrointestinal side effects are rare because hundreds of ferric iron atoms are safely packed in nanoscaled cores surrounded by the solubilizing shell; nevertheless, iron bioavailabi…
Sol-gel entrapped chromium(VI): a new selective, efficient and recyclable oxidizing system
2001
Abstract The sol-gel entrapment of chromium(VI) within a silica matrix, obtained by oxidation with ozone of the corresponding entrapped chromium(III), was found to be an efficient and recyclable oxidizing system (at least up to 16 times) for benzylic alcohols. No leaching of chromium in solution was observed, which prevented any environmental pollution.
Heterogeneous borrowing hydrogen reactions with Pd/C and ZnO: Diol scope
2017
Abstract A borrowing hydrogen reaction with different diols was employed for the preparation of complex beta- gamma- or epsilon-amino alcohols from p-toluidine and tetrahydroquinoline with the aim of better understanding the applicability of the Pd/C ZnO heterogeneous catalyst.
Synthesis of 2,4,6-trisubstituted tetrahydropyrans via 6-exo selenoetherification of unsaturated alcohols
2001
Stereoselectivity, regioselectivity and yields in the 6-exo selenoetherification of four unsaturated diols were found to depend on the stereochemistry of the diols and on the presence of an oxygen atom close to the intermediate seleniranium ring. Silica gel was useful in order to obtain good yields. Reactions performed both under kinetic and thermodynamic control led to the same products. Stereoselectivity, regioselectivity and yields in the 6-exo selenoetherification of four unsaturated diols were found to depend on several factors such as the stereochemistry of the diols, the nature of the R group, the nature of the counter anion of the PhSe+ species and the presence of silica gel.
A facile cleavage of allyl ethers on solid phase
2000
Abstract A simple and efficient protocol for the cleavage of allyl ethers on solid phase using a palladium(0)-catalyzed allyl transfer reaction is reported.
Receptor-mediated uptake of boron-rich neuropeptide y analogues for boron neutron capture therapy.
2014
Peptidic ligands selectively targeting distinct G protein-coupled receptors that are highly expressed in tumor tissue represent a promising approach in drug delivery. Receptor-preferring analogues of neuropeptide Y (NPY) bind and activate the human Y1 receptor subtype (hY1 receptor), which is found in 90% of breast cancer tissue and in all breast-cancer-derived metastases. Herein, novel highly boron-loaded Y1 -receptor-preferring peptide analogues are described as smart shuttle systems for carbaboranes as (10) B-containing moieties. Various positions in the peptide were screened for their susceptibility to carbaborane modification, and the most promising positions were chosen to create a mu…
Synthese und pharmakologische Wirkung von carbocyclischen Muskarinanalogen
1974
Als carbocyclische Muskarinanaloga wurden das (3-Hydroxycyclopentylmethyl)trimethyl-ammonium-jodid und dessen Acetat dargestellt und am isolierten Ileum des Meerschweinchens untersucht. Synthesis and Pharmacological Activity of Carbocyclic Analogs of Muscarine As carbocyclic analogs of muscarine (3-hydroxycyclopentylmethyl)trimethylammonium iodide and (3-acetoxycyclopentylmethyl)trimethylammonium iodide were synthesized and tested on the isolated guinea pig ileum.
Synthesis of a Tyr3-octreotate conjugated closo-carborane [HC2B10H10]: a potential compound for boron neutron capture therapy
2003
Abstract A novel Tyr 3 -octreotate conjugated closo -carborane as a potential compound for boron neutron capture therapy was obtained via Fmoc solid phase peptide synthesis. The boron cluster [C 2 B 10 H 11 ] was introduced through the reaction of 6,9-bis(acetonitrile)decaborane and 5-hexynoic acid yielding a new closo -carborane conjugated carboxylic acid which was coupled subsequently with solid phase conjugated Tyr 3 -octreotate. The final boron-containing peptide was purified by preparative reverse phase HPLC and structural identity was proved applying MALDI-TOF mass spectrometry.