Volatile Compound Formation During Argan Kernel Roasting

Virgin edible argan oil is prepared by cold-pressing argan kernels previously roasted at 110°C for up to 25 minutes. The concentration of 40 volatile compounds in virgin edible argan oil was determined as a function of argan kernel roasting time. Most of the volatile compounds begin to be formed after 15 to 25 minutes of roasting. This suggests that a strictly controlled roasting time should allow the modulation of argan oil taste and thus satisfy different types of consumers. This could be of major importance considering the present booming use of edible argan oil

Acide lysergique et dérivés, aspects synthétique et applications

REIMS-BU Santé (514542104) / SudocSudocFranceF

Nouvelles méthodes de génération et d'activation de complexes zirconocènes (Synthèse de composés azotés)

Ce mémoire concerne le développement de nouvelles méthodes d activation de complexes zirconocènes reposant sur une coopération bimétallique. Cette démarche a été appliquée à la synthèse de composés azotés. La première partie de ce travail est consacrée au développement d une réaction hautement chimiosélective de carboalumination d aldimines sous catalyse au zirconium. Cette réaction met en jeu des alanes en tant que source de groupements alkyls et procède via l établissement d un complexe bimétallique. Dans le cas des imines dérivées de l aniline une réaction d acylation régiosélective en position ortho, également catalysée par le zirconium, peut être mise en oeuvre. Dans la deuxième partie, nous avons développé une synthèse diastéréosélective de pyrrolidines substituées en position 2- et 2,5-. Celles-ci sont obtenues à partir de Nallyloxazolidines optiquement pures selon une séquence d hydrozirconation / cyclisation activée par un acide de Lewis. Au cours du troisième chapitre, nous avons développé une méthode de préparation stéréosélective de g-lactames via une réaction de couplage intramoléculaire de carbamates homoallyliques impliquant la chimie du zirconium(II). Enfin, la dernière partie de cette thèse a été consacrée au développement d un nouveau réactif, équivalent synthétique du zirconocène(II). Celui-ci est obtenu par réduction du dichlorure de zirconocène par un alliage de lanthanides, le mischmetall. Ce nouveau réactif a montré un fort potentiel synthétique dans de nombreux couplages et a notamment permis d utiliser, pour la première fois, des alcynes vrais et de réaliser la première trimérisation d alcynes catalysée par le zirconium.This memory deals with the development of new methods for activation of zirconocene complexes through a bimetallic co-operation. New syntheses of nitrogencontaining compounds have been developed on this basis. The first part of this work is devoted to the highly chemoselective carboalumination of aldimines under zirconium catalysis. This reaction involves alanes as alkyl promotors and proceeds through metallacycles involving a bimetallic polarisation. In the case of imines derived from aniline, a zirconium-catalyzed regioselective acylation at the ortho position can be carried out. In the second part, we developed a new diastereoselective synthesis of 2- and 2,5- substituted pyrrolidines starting from optically pure N-allyloxazolidines, according to a hydrozirconation/ Lewis acid-catalyzed cyclization sequence. The third chapter presents a stereoselective synthesis of g-lactams from N-homoallylcarbamates, by using a zirconium (II)-mediated intramolecular coupling reaction. Finally, the last part of this thesis was devoted to the development of a new reagent, synthetic equivalent of zirconocene(II). This reagent is obtained by reduction of dichlorozirconocene with a lanthanide alloy, the mischmetall. This new reagent possesses an important synthetic potential in many couplings. In particular, the first coupling involving 1- alkynes and the first zirconium catalyzed trimerisation of alkynes have been carried out.REIMS-BU Sciences (514542101) / SudocSudocFranceF

Synthèse de nouveaux inhibiteurs pseudodipeptidiques dérivés de la Galardine (étude de leur séléctivité sur les métalloprotéinases matricielles)

REIMS-BU Santé (514542104) / SudocSudocFranceF

Zincate‐Mediated Remote Functionalisation of p ‐Iodobenzyl Derivatives Through Metallotropy in 2‐Methyltetrahydrofuran as Key Solvent

International audience2-MeTHF (2-methyltetrahydrofuran) promotes the zincate-mediated remote functionalisation of p-iodobenzyl derivatives through metallotropy with a broad scope. This biosourced solvent remarkably impacted all the key elementary steps involved in the tandem reaction. The method tolerates a wide range of sensitive functionalities within the substrates as well as enolisable and activated or deactivated aromatic aldehydes as reaction partners. A challenging benzyl naphthalene derivative was even reacted through an original dearomatisation/rearomatisation/metallotropy chain

Stereoselective Synthesis of Pyrrolidines from N -Allyl Oxazolidines via Hydrozirconation−Cyclization

International audienceA new diastereoselective synthesis of pyrrolidines from readily available chiral N-allyl oxazolidines is presented. The construction of the pyrrolidine ring is achieved via a tandem hydrozirconation−stereoselective Lewis acid mediated cyclization sequence

Revisiting the Sweet Taste Receptor T1R2-T1R3 through Molecular Dynamics Simulations Coupled with a Noncovalent Interactions Analysis

It is nowadays widely accepted that sweet taste perception is elicited by the activation of the heterodimeric complex T1R2-T1R3, customarily known as sweet taste receptor (STR). However, the interplay between STR and sweeteners has not yet been fully clarified. Here through a methodology coupling molecular dynamics and the independent gradient model (igm) approach we determine the main interacting signatures of the closed (active) conformation of the T1R2 Venus flytrap domain (VFD) toward aspartame. The igm methodology provides a rapid and reliable quantification of noncovalent interactions through a score (Δginter) based on the attenuation of the electronic density gradient when two molecular fragments approach each other. Herein, this approach is coupled to a 100 ns molecular dynamics simulation (MD-igm) to explore the ligand-cavity contacts on a per-residue basis as well as a series of key inter-residue interactions that stabilize the closed form of VFD. We also apply an atomic decomposition scheme of noncovalent interactions to quantify the contribution of the ligand segments to the noncovalent interplay. Finally, a series of structural modification on aspartame are conducted in order to obtain guidelines for the rational design of novel sweeteners. Given that innovative methodologies to reliably quantify the extent of ligand-protein coupling are strongly demanded, this approach combining a noncovalent analysis and MD simulations represents a valuable contribution, that can be easily applied to other relevant biomolecular systems.Revisión por pare

The Mechanism of Lithium Zincate-Mediated I/Zn Exchange Revisited: A Computational Micro-Solvation Approach in THF

Lithium trialkylzincate-mediated I/Zn exchange reaction has been revisited computationally through a micro-solvation approach. A never yet investigated iodoaryl derivative bearing a potential bulky para-directing group, namely 4-iodobenzyl mesylate, was considered as a substrate. THF as typical solvent and Et3ZnLi have also been considered for the first time in such a reaction. Four mechanistic pathways have been calculated, including a literature-inspired pathway with preservation of the synergic character of the reagent (pathway 1), an OMs-directed I/Zn exchange pathway (pathway 2), a THF-solvated open complex-promoted pathway (pathway 3) and an anionic pathway (pathway 4). While pathway 4 could be fully precluded, pathway 3 turned out to be the most energetically favoured. Equivalent thermodynamic profiles were found for both pathways 1 and 2, albeit a slight preference can be attributed to the latter through micro-solvation approach. The I/Zn exchange was shown to proceed through a lithium-assisted aryl shuttle-like process. The iodoaryl substrate is first converted into ArLi intermediate which in turns reacts with the remaining diorganozinc reagent

SN- and NS-puckered sugar conformers are precursors of the (6–4) photoproduct in thymine dinucleotide

International audienceThe S conformation of at least one sugar residue in the TT site is crucial for (6–4) PP formation. This S sugar can be located at the 5′- or 3′-end of the TT site. The 5′-end S conformer location is the most efficient at providing (6–4) PP

Synthesis of novel chiral 1,4-dihydropyridinyl Schiff-base ligands, with characterization and evaluation of calcium channel blocker activity

International audienc