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Neier, Reinhard

Nom
Neier, Reinhard
Affiliation principale
Fonction
Professeure ordinaire
Email
Reinhard.Neier@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/383
_
0000-0003-0890-1797

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  • Publication
    Accès libre
    Macrocyclisation of 2-(5-(2-hydroxyethyl)furan-2-yl)acetic acid model compounds of nonactic acid
    (2009)
    Eng, Carine
    ;
    Simone, Jean-Mary
    ;
    Hartenbach, Akane
    ;
    Loiseau, François
    ;
    Neier, Reinhard 
    The macrocyclisation of hydroxyethylfuranyl acetic acid and of dehydrogenated model compounds of nonactic acid was investigated to develop a facile synthesis of nonactin analogues. By applying the Yamagushi macrocyclisation to our ω-hydroxyacids, we were able to isolate a mixture of di-, tri-, tetra- and pentameric macrocycles.
  • Publication
    Accès libre
    Malonylation/Decarbalkoxylation of Furan Derivatives as Key Steps for the Preparation of Nonactic Acid Derivatives. Part II [1]
    (2007)
    Simone, Jean-Mary
    ;
    Loiseau, François
    ;
    Carcache, David
    ;
    Bobal, Pavel
    ;
    Jeanneret-Gris, Julie
    ;
    Neier, Reinhard 
    A malonylation/decarbalkoxylation sequence from 2-substituted furans was investigated in view of developing a scalable synthesis of hydrophobic nonactic acid analogues.
  • Publication
    Accès libre
    Radical Couplings as Key Steps for the Preparation of Derivatives of Nonactic Acid
    (2007)
    Loiseau, François
    ;
    Simone, Jean-Mary
    ;
    Carcache, David
    ;
    Bobal, Pavel
    ;
    Neier, Reinhard 
    Free radical couplings from furan, as cheap starting material, were studied in view of developing a rapid strategy en route to the synthesis of derivatives of nonactin. The chain containing the alcohol function was introduced in one or two steps in 86% yield. For the introduction of the second chain with the ester function two different coupling methods were tested. Starting from the advanced intermediates obtained nonactin derivatives can be prepared by catalytic hydrogenation of the furan ring.
  • Publication
    Accès libre
    Malonylation/Decarbalkoxylation of Furan Derivatives as Key Steps for the Preparation of Nonactic Acid Derivatives. Part I [1]
    (2007)
    Simone, Jean-Mary
    ;
    Loiseau, François
    ;
    Carcache, David
    ;
    Bobal, Pavel
    ;
    Jeanneret-Gris, Julie
    ;
    Neier, Reinhard 
    A malonylation/decarbalkoxylation sequence from 2-substituted furans was investigated in view of developing a scalable synthesis of hydrophobic nonactic acid analogues.
  • Publication
    Accès libre
    rac-(R)-2-[(2R,5R)-5-Methyl­tetra­hydro­furan-2-yl]propanoic acid
    (2006)
    Loiseau, François
    ;
    Neier, Reinhard 
    ;
    Stoeckli-Evans, Helen 
    In the crystal structure of the title compound, C8H14O3, the 2,5-tetra­hydro­furan ring junction is cis. The relative configuration of position 2 in the propanoic acid group was found to be the same as that in positions 2 and 5 in the tetra­hydro­furan ring. In the crystal structure, symmetry-related mol­ecules are linked by O***HO hydrogen bonds to form centrosymmetric dimers.
  • Publication
    Accès libre
    rac-Ethyl 2-bromo-2-[(3R,5R)-3-bromo-5-methyltetrahydrofuran-2-ylidene]acetate
    (2006)
    Loiseau, François
    ;
    Neier, Reinhard 
    ;
    Labat, Gael
    ;
    Stoeckli-Evans, Helen 
    In the title compound, C9H12Br2O3, a (tetrahydrofuran-2-ylidene)acetate, the double bond has the Z form. In the tetrahydrofuran group, the relative configuration of the Br atom in the 3-position and the methyl group in the 5-position is anti. The compound crystallizes with two independent molecules per asymmetric unit and, in the crystal structure, the individual molecules are linked to their symmetry-equivalent molecules by C***HO hydrogen bonds, so forming centrosymmetric hydrogen-bonded dimers.
  • Publication
    Accès libre
    Synthèse de dérivés de l'acide nonactique: études de méthodes pour introduire diastéréosélectivement des chaînes hydrophobes sur la nonactine
    (2006)
    Loiseau, François
    ;
    Neier, Reinhard 
    La nonactine est un antibiotique utilisé dans les électrodes sélectives d’ions ammonium. Notre objectif a été de développer des méthodes permettant de greffer des chaînes hydrophobes sur la nonactine, afin d’augmenter sa durée de vie dans la membrane semi-perméable des senseurs. D’abord, des analogues simples de l’acide nonactique, tels que 275, ainsi qu’un dimère linéaire, ont été synthétisés à partir de produits de départ peu coûteux. Ces dérivés ont été utilisés comme modèles afin d’évaluer les modifications possibles de la nonactine. Le défi de la transformation est de ne pas affecter les centres chiraux de la jonction de cycle cis. Trois principales routes ont été développées pour synthétiser 329 par greffage d’une chaîne allylique sur 275. La route I, une méthode directe via l’énolate, est réalisée grâce au KHMDS comme base et l’iodure d’allyle. Cependant, parallèlement à 329, les produits 330 et 335 sont formés via une réaction de rétro-Michael intramoléculaire menant à 330 et 335. Deux routes alternatives ont alors été imaginées. La route II consiste en une séquence rétro-Michael, suivie d’une iodocyclisation 5-exo-tet, et d’une substitution radicalaire. La route III repose sur la chimie du thione-ester 383. En maintenant à -78°C la température du thione-énolate de 383, généré par du tert-BuOK, le composé 329 a pu être obtenu avec un degré de diastéréosélectivité suffisant en faveur de la jonction de cycle cis (cis : trans = 85 : 15)., The antibiotic nonactin is used in ammonium ion selective electrodes. Our goal is to develop methods to introduce hydrophobic side chains on nonactin, in order to increase its life time in the semi permeable membrane of a sensor. Simple nonactic acid derivatives such as 275, and a dimer, were synthesized from cheap starting materials. In order to study the possibility of modifying nonactin, these derivatives were used as model compounds. The challenge is to maintain the chiral centres of the cis ring junction during the transformations. Three main routes were developed to synthesize 329 by adding an allylic chain on 275. Route I, a direct method using enolate chemistry, was performed using KHMDS as a base and allyl iodide. As the intramolecular retro-Michael reaction leading to 330 and 335 can not be totally avoided, two multi steps methodologies were developed. Route II consists of a sequence of retro-Michael reaction, 5-exo-tet iodocyclisation, and radical substitution. Route III uses thione-ester chemistry. The thione-enolate of 383 was generated by tert-BuOK as a base. By maintaining the temperature below -78°C, this latter methodology leads to a sufficient degree of diastereoselectivity in favour of the expected cis ring junction of 329 (cis : trans = 85 : 15).