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6 results on '"Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM)"'

1. The β-phosphorus hyperfine coupling constant in nitroxides: 6. Solvent effects in non-cyclic nitroxides

Author

Paul Brémond, Raphael Bikanga, Lionel Bosco, Sylvain R. A. Marque, Gérard Audran, Paulin Nkolo, Teddy Butscher, Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Lab Substances Naturelles (LASUNA), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), and Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)

Subjects
ALKOXYAMINE, Nitroxide mediated radical polymerization, Radical, HOMOLYSIS, 010402 general chemistry, Photochemistry, 01 natural sciences, Biochemistry, PROBES, law.invention, ELECTRON-PARAMAGNETIC-RESONANCE, law, Polarizability, RADICALS, [CHIM]Chemical Sciences, Molecule, Physical and Theoretical Chemistry, Electron paramagnetic resonance, 010405 organic chemistry, Chemistry, Hydrogen bond, Organic Chemistry, 0104 chemical sciences, Homolysis, NITROGEN, Solvent effects, POLARITY
Abstract

International audience; In two recent articles (Org. Biomol. Chem., 2015 and 2016), we showed that changes in the phosphorus hyperfine coupling constant a(P) at position beta in beta-phosphorylated nitroxides can be dramatic. Such changes were applied to the titration of water in organic solvents and conversely of organic solvents in water. One of the molecules tested was a non-cyclic nitroxide meaning that a thorough investigation of the solvent effect on the EPR hyperfine coupling constant is timely due. In this article, we show that the aP of persistent non-cyclic beta-phosphorylated nitroxides decrease with the normalized polarity Reichardt's constant ENT. The Koppel-Palm and Kalmet-Abboud-Taft relationships were applied to gain deeper insight into the effects influencing a(N) and a(P): polarity/polarizability, hydrogen bond donor properties, and the structuredness of the cybotactic region.

Published
2016

2. C-ON bond homolysis of alkoxyamines: when too high polarity is detrimental

Author

Gigmes, Didier, Nkolo, Paul, Audran, Gérard, Bikanga, Raphaël, Brémond, Paul, Marque, Sylvain, Roubaud, Valérie, Institut de Chimie Radicalaire (ICR), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Laboratoires de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), and Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)

Subjects
chemistry.chemical_classification, Nitroxide mediated radical polymerization, 010405 organic chemistry, Stereochemistry, Organic Chemistry, Nitroxyl, 010402 general chemistry, 01 natural sciences, Biochemistry, Medicinal chemistry, 0104 chemical sciences, Homolysis, chemistry.chemical_compound, Reaction rate constant, chemistry, Polar effect, [CHIM]Chemical Sciences, Methanol, Physical and Theoretical Chemistry, Solvent effects, Alkyl, ComputingMilieux_MISCELLANEOUS
Abstract

Throughout the last decade, the effect of electron withdrawing groups (EWGs) has been known to play a role - minor or moderate depending on the nitroxyl fragment R1R2NO - in the change in the homolysis rate constant (kd) for C-ON bond homolysis in alkoxyamines (R1R2NOR). It has been shown that the effect of EWGs on kd is described by a linear relationship with the electrical Hammett constant σI. Since then, linear multi-parameter relationships f(σRS,ν,σI) have been developed to account for the effects involved in the changes in kd, which are the stabilization of the released radical (σRS) and the bulkiness (ν) and polarity (σI) of the alkyl fragment. Since a decade ago, new results have been published highlighting the limits of such correlations. In this article, previous multi-parameter linear relationships are amended using a parabolic model, i.e. (σI,nitroxide - σI,alkyl)2, to describe the effect of EWGs in the alkyl fragment on kd. In contrast to previous studies, these improved linear multi-parameter relationships f(σRS,ν,ΔσI2) are able to account for the presence of several EWGs on the alkyl fragment, R. An unexpectedly strong solvent effect - a ca. 1500-fold increase in kd - from tert-butylbenzene to the water/methanol mixture is also observed for 3-((2,2,6,6-tetramethylpiperidin-1-yl)oxyl)pentane-2,4-dione 1b in comparison to a ca. 5-fold increase in kd that is generally observed.

Published
2017

3. Normal, Leveled, and Enhanced Steric Effects in Alkoxyamines Carrying a beta-Phosphorylated Nitroxyl Fragment

Author

Gérard Audran, Paul Brémond, Raphael Bikanga, Jean-Patrick Joly, Sylvain R. A. Marque, Paulin Nkolo, Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM), Lab Substances Naturelles (LASUNA), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Steric effects, family, 010405 organic chemistry, Chemistry, Stereochemistry, Organic Chemistry, Nitroxyl, mediated polymerization, 010402 general chemistry, 01 natural sciences, on bond homolysis, 0104 chemical sciences, Homolysis, chemistry.chemical_compound, Reaction rate constant, Fragment (logic), styrene, Phosphorylation, [CHIM]Chemical Sciences, polar, rate-constant, free-radical polymerization, polymers, bearing
Abstract

International audience; The design of new R1R2NOR3 alkoxyamines for various applications relies on the accurate prediction of two kinetic parameters, the C-ON bond homolysis rate constant (k(d)) and its re-formation rate constant (k(c)). Relationships to describe the steric and polar effects of the R1R2NO fragment ruling k(d) have been developed. For all cyclic nitroxyl fragments, the steric effect is described as the sum of the bulkiness of the R-1 and R-2 groups (i.e., normal steric effect), while for the noncyclic nitroxyl fragment (except for one case), a leveled steric effect is assumed. In this work, we show that the normal steric effect also applies to noncyclic nitroxyl fragments and that for one case an enhanced steric effect is also observed, i.e., experimental k(d) \\textgreater 5-fold larger than the predicted value.

Published
2017

4. Hyperfine coupling constants of beta-phosphorylated nitroxides: Subtle interplay between steric strain, hyperconjugation, and dipole-dipole interactions

Author

Paul Brémond, Gérard Audran, Raphael Bikanga, Sylvain R. A. Marque, Paulin Nkolo, Valérie Roubaud, Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM), Lab Substances Naturelles (LASUNA), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Polarity (physics), Solvent effect, 010402 general chemistry, Hyperconjugation, Photochemistry, 01 natural sciences, Biochemistry, nitrogen, Hyperfine coupling, Drug Discovery, [CHIM]Chemical Sciences, Physics::Chemical Physics, mri, solvent polarity, 010405 organic chemistry, Chemistry, Hydrogen bond, Organic Chemistry, Nitroxides, electron-transfer, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 0104 chemical sciences, Solvent, Dipole, Crystallography, parameter, resonance, Multi-parameter analysis, Solvent effects, solvation, probes, esr, EPR spectroscopy
Abstract

International audience; Solvent effects in beta-phosphorylated nitroxides show that nitrogen and phosphorus hyperfine coupling constants a(N) and a(p), increase and decrease with increasing polarity, polarizity, and Hydrogen Bond Donor effects of solvents, respectively. In a series of articles, it was shown that the driving interaction controlling the change in a(p) is the maximization of the N+center dot O-center dot center dot center dot center dot center dot center dot P+-O- dipole - dipole interaction. In this work, we show that the steric strain in Spiro beta-phosphotylated nitroxides affords the opposite trend for a(p) that is, a(p) increases with increasing solvent properties features. (C) 2017 Elsevier Ltd. All rights reserved.

Published
2017

5. How intramolecular hydrogen bonding (IHB) controls the C-ON bond homolysis in alkoxyamines

Author

Mariya V. Edeleva, Paul Brémond, Raphael Bikanga, Valérie Roubaud, Gérard Audran, Sylvain R. A. Marque, Jean-Patrick Joly, Paulin Nkolo, Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM), N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, ANR-14-CE16-0023,NORMATHER,Etude et inhibition de l'activation des cellules endothéliales dans la vascularisation physiologique et pathologique de la rétine.(2014), Lab Substances Naturelles (LASUNA), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), Institut de Chimie Radicalaire ( ICR ), Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), Lab Substances Naturelles ( LASUNA ), Université des Sciences et Techniques de Masuku, ANR-14-CE16-0023,NORMATHER,Etude et inhibition de l’activation des cellules endothéliales dans la vascularisation physiologique et pathologique de la rétine. ( 2014 ), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
family, Protonation, 010402 general chemistry, Photochemistry, chemistry, 01 natural sciences, Biochemistry, Medicinal chemistry, chemistry.chemical_compound, Reaction rate constant, [ CHIM.ORGA ] Chemical Sciences/Organic chemistry, polar, Physical and Theoretical Chemistry, Alkyl, chemistry.chemical_classification, 010405 organic chemistry, Hydrogen bond, Chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Organic Chemistry, Nitroxyl, constants, 0104 chemical sciences, 3. Good health, Homolysis, Intramolecular force, derivatives, nitroxyl fragment, Solvent effects, free-radical polymerization
Abstract

International audience; Recent amazing results (Nkolo et al., Org. Biomol. Chem., 2017, 6167) on the effect of solvents and polarity on the C-ON bond homolysis rate constants kd of alkoxyamine R1R2NOR3 led us to re-investigate the antagonistic effect of intramolecular hydrogen-bonding (IHB) on kd. Here, IHB is investigated both in the nitroxyl fragment R1R2NO and in the alkyl fragment R-3, as well as between fragments, that is, the donating group on the alkyl fragment and the accepting group on the nitroxyl fragment, and conversely. It appears that IHB between fragments (inter IHB) strikingly decreases the homolysis rate constant kd, whereas IHB within the fragment (intra IHB) moderately increases kd. For one alkoxyamine, the simultaneous occurrence of IHB within the nitroxyl fragment and between fragments is reported. The protonation effect is weaker in the presence than in the absence of IHB. A moderate solvent effect is also observed.

Published
2017

6. One-pot microwave-assisted synthesis and antimalarial activity of ferrocenyl benzodiazepines

Author

Jean-Bernard Lekana-Douki, Philippe Grellier, Fousseyni S. Touré Ndouo, Gabin Mwande-Maguene, Sylvain Pellegrini, Jacques Lebibi, Till Bousquet, Jouda Jakhlal, Lydie Pelinski, Elisabeth Mouray, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Département de Parasitologie, Mycologie et Médecine Tropicale, Faculté de Médecine-Université de Libreville, Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Lab Substances Naturelles (LASUNA), Université des Sciences et Techniques de Masuku [Franceville, Gabon] (USTM), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Substances Naturelles et de Synthèses Organométalliques (LASNSOM), Unité de Recherche en Chimie [Université des Sciences et Techniques de Masuku] (URCHI), Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)-Ecole Doctorale des Sciences Fondamentales et Appliquées [Université des Sciences et Techniques de Masuku] (EDSFA), and Université des Sciences et Techniques de Masuku (USTM)-Université des Sciences et Techniques de Masuku (USTM)

Subjects
chemistry.chemical_classification, biology, 010405 organic chemistry, Chemistry, Condensation, Plasmodium falciparum, General Chemistry, 010402 general chemistry, biology.organism_classification, 01 natural sciences, Microwave assisted, Catalysis, 3. Good health, 0104 chemical sciences, Amino acid, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Materials Chemistry, [CHIM]Chemical Sciences, Organic chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

An efficient synthesis of 1,4-benzodiazepin-2-ones is described by condensation between 2-aminobenzophenone and Boc-protected amino acids via microwave-assisted irradiation. This produces higher yields in shorter reaction times than with traditional methods. The antiplasmodial activity of the corresponding ferrocenyl benzodiazepines was evaluated in vitro against Plasmodium falciparum F32 (chloroquine-sensitive) and FCB1 and K1 (chloroquine-resistant) strains and gabonese clinical isolates.

Published
2011

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