Search results for "SELECTIVITY"
showing 10 items of 1148 documents
A DFT study of the role of the Mg complex formation on the mechanism of the 1,3-dipolar cycloadditions of benzonitrile oxides with acryloylpyrazolidi…
2010
Abstract The role of the Mg complex formation on the mechanism, the reaction rate and regioselectivity of the 1,3-dipolar cycloaddition (13DC) reactions of benzonitrile oxides (BNOs) towards electron-deficient acryloylpyrazolidinones has been theoretically studied using DFT methods at the 6-31G* level. These 13DC reactions have asynchronous concerted mechanism with a non-polar character. These cycloadditions present a slight 5-regioselectivity induced by a steric repulsion between the phenyl substituent of the BNOs and the pyrazolidinone appendage present on the acryloyl derivative, which increases with the formation of the bulky Mg–acryloylpyrazolidinone complex. The present DFT study poin…
Evaluation of the electrochemical anion recognition ofNO3−-imprinted poly(Azure A) inNO3−/Cl−mixed solutions by ac-electrogravimetry
2016
Abstract During the reversible electrochemical reactions of the intrinsically conducting polymer (ICP) films, ions are inserted in them to balance the inner charge site of the polymer. For this reason, doped ICP films with anions or cations can be good candidates for the electrochemical removal of contaminant ions from wastewater. In this work, a polymer of a phenothiazine derivative (poly(Azure A or PAA)) was electrosynthesized by cyclic voltammetry in aqueous solutions using nitrate ions as a structural template. After that, PAA film was repeatedly cycled in identical conditions in a monomer-free solution. The electrochemical anion recognition of the nitrate-imprinted poly(Azure A) ( N O …
Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination
2019
Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…
Synthesis of potentially anti-inflammatory IPL576,092-contignasterol and IPL576,092-manoalide hybrids
2004
The synthesis of two potentially anti-inflammatory steroidal hybrid compounds has been accomplished through a 16- and 17-step sequence, respectively, starting from commercially available androst-5-en-3β-ol-17-one. The synthetic strategies are based both on stereoselective side chains elaboration and high yielding functional group transformations.
Janus Micelles Induced by Olefin Metathesis
2008
A facile one-step procedure for hydrophobic modification and simultaneous TEM contrast enhancement via a regioselective olefin metathesis reaction using Grubbs' catalyst is presented. Polyether diblock copolymers were investigated, and both the chain ends of the hydrophilic and the hydrophobic block were hydrophobically modified. Modification of the hydrophilic block results in nonsymmetric supramolecular structures (Janus micelles) which self-assemble into larger hierarchically organized super-micelles.
Bioactive pyrrole-based compounds with target selectivity
2020
The discovery of novel synthetic compounds with drug-like properties is an ongoing challenge in medicinal chemistry. Natural products have inspired the synthesis of compounds for pharmaceutical application, most of which are based on N-heterocyclic motifs. Among these, the pyrrole ring is one of the most explored heterocycles in drug discovery programs for several therapeutic areas, confirmed by the high number of pyrrole-based drugs reaching the market. In the present review, we focused on pyrrole and its hetero-fused derivatives with anticancer, antimicrobial, and antiviral activities, reported in the literature between 2015 and 2019, for which a specific target was identified, being resp…
ChemInform Abstract: Enantioselective Palladium-Catalyzed Oxidative β,β-Fluoroarylation of α,β-Unsaturated Carbonyl Derivatives.
2016
The site-selective palladium-catalyzed three-component coupling of deactivated alkenes, arylboronic acids, and N-fluorobenzenesulfonimide is disclosed herein. The developed methodology establishes a general, modular, and step-economical approach to the stereoselective β-fluorination of α,β-unsaturated systems.
Cover Picture: Source of Selectivity in Oxidative Cross-Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3-Hexafluoropropan-2-ol (Chem. Eur. J. 35/20…
2015
A convenient synthesis of unsymmetrically substituted terphenyls of biologically active stilbenes via a double Suzuki cross-coupling protocol
2003
A double Suzuki cross-coupling protocol has been devised as a practical route to a variety of terphenyls. Good chemoselectivity was observed. Unsymmetrically substituted triphenylenes were also easily prepared.
The product of a regiospecific and stereoselective ene-reaction of a polycyclic terpenoid system
2001
The X-ray structure of dimethyl (Z)-[(8aS,2R,4aR,4bR)-8a-methoxycarbonyl-1,4a,7-trimethyl-8-oxo-2,3,4,4a,4b,5,8,8a,9,10-decahydrophenanthren-2-yl]-2-butenedioate, C25H32O7, confirmed its relative configuration. The structure shows the bend in the molecular skeleton as found for similar compounds. Weak intermolecular C—H⋯O interactions have been found in the crystal.