18 research outputs found
SynthÚse de cyclopentÚnes et d'époxydiynes fonctionnalisés, vers la synthÚse de diÚnediynes naturels
Les diĂšnediynes sont une famille de substances naturelles aux propriĂ©tĂ©s biologiques d intĂ©rĂȘt clinique, essentiellement des activitĂ©s antitumorales ou antibiotiques. Parmi cette famille s est particuliĂšrement dĂ©marquĂ© la nĂ©ocarzinostatine (NCS), utilisĂ©e en clinique pour traiter essentiellement les cancers du foie. Le chromophore de la NCS est une molĂ©cule hautement rĂ©active stabilisĂ©e par une protĂ©ine Ă l Ă©tat naturel, qui n a, Ă ce jour, fait l objet que d une seule synthĂšse totale. La N1999-A2 possĂšde une structure fort similaire et a fait l objet de deux synthĂšses totales.Ce travail traite de la synthĂšse de ces deux composĂ©s selon une stratĂ©gie reposant sur la formation finale du cycle diĂšnediyne par couplages successifs de deux fragments de complexitĂ© Ă©quivalente : un fragment cyclopentanique (CyP) et un fragment Ă©poxydiyne (EdY). La synthĂšse du fragment CyP a Ă©tĂ© Ă©tudiĂ©e et certains points clĂ©s de la synthĂšse telles que la rĂ©action de Baylis-Hillman ou la formation stĂ©rĂ©osĂ©lective d Ă©thers d Ă©nols de triflate Ă partir d un cĂ©to-aldĂ©hyde ont Ă©tĂ© dĂ©veloppĂ©s. Cette rĂ©action a Ă©tĂ© Ă©tendue Ă d autres systĂšmes b-dicarbonylĂ©s ainsi qu aux cĂ©to-sulfones et cĂ©to-phosphonates avec un contrĂŽle total de la stĂ©rĂ©ochimie Z du triflate de vinyle formĂ©. La synthĂšse du fragment EdY a Ă©galement Ă©tĂ© rĂ©alisĂ©e impliquant notamment l addition d un anion oxiranique sur un carbonyle ainsi que la rĂ©duction diastĂ©rĂ©osĂ©lective de l a,b-Ă©poxycĂ©tone ainsi formĂ©e. Une version asymĂ©trique de la synthĂšse des fragments CyP et EdY a Ă©tĂ© rĂ©alisĂ©e suivant une stratĂ©gie de rĂ©solution enzymatique. Des essais prĂ©liminaires de couplage de prĂ©curseurs des fragments CyP et EdY ont Ă©tĂ© effectuĂ©s.Dienediynes consist in a series of natural compounds exhibiting similar structures and antitumor and antibiotic activites. One of these compounds, neocarzinostatin (NCS), a protein stabilized compound, was extensively studied for its antitumor properties and even applied to clinical use. Due to its unstability, only a single synthesis has so far been achieved. Another dienediyne, N1999-A2, structurally similar to NCS, exhibit similar antibiotic activities and was synthesized twice.This work deals with the total synthesis of both natural compounds according to a strategy that relies on the final formation of the dienediyne core by successive cross-coupling of two fragments: a cyclopentane fragment (CyP) and an epoxydiyne fragment (EdY). The synthesis of the CyP fragment was studied and several key reactions were specifically developed, such as the Baylis-Hillman reaction or the stereocontrolled formation of Z vinyl triflate from a keto-aldehyde. The latter reaction was extended to several b-dicarbonylated systems and to keto-sulfones and keto-phosphonates with a full Z control of the so-formed vinyl triflate. The synthesis of the EdY fragment was performed following a new sequence including a new reaction i.e. oxirane anion acylation and diastereoselective reduction of the so-formed a,b-epoxyketone. Asymmetric versions of both CyP and EdY syntheses were achieved, based on enzymatic resolution strategy. Furthermore, preliminary results were obtained for the cross-coupling of CyP and EdY fragments precursors.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF
Chemoselective Synthesis of ÎČâKetophosphonates Using Lithiated αâ(Trimethylsilyl)methylphosphonate
A highly
chemoselective synthesis of ÎČ-ketophosphonates from
pentafluorophenyl esters and lithiated methyl α-(trimethylsilyl)Âmethylphosphonate
has been developed. This mild lithiated phosphonate reagent allows
the synthesis of functionalized ÎČ-ketophosphonates in the presence
of unactivated esters with high yields. This method has been compared
with the standard lithiated methylphosphonate reagent
Stereoselective Ring-Opening of gem -Difluorocyclopropanes: An Entry to Stereo-defined ( E , E )- and ( E , Z )-Conjugated Fluorodienes
International audienc
Strength by joining methods: combining synthesis with NMR, IR, and vibrational circular dichroism spectroscopy for the determination of the relative configuration in hemicalide
The relative configuration of a key subunit of hemicalide, a recently isolated, highly bioactive marine natural product having potent antiproliferative activity against a panel of human cancer cell lines, was assigned by combining stereocontrolled synthesis of model substrates with NMR, IR, and vibrational circular dichroism (VCD) spectroscopy. The assignment of the absolute configuration of asymmetric carbon center C42 in two structurally complex epimeric substructures containing six stereocenters by VCD analysis illustrates the power and reliability of combining methods
One-Pot Synthesis of 1,4-Disubstituted Pyrazoles from Arylglycines via Copper-Catalyzed SydnoneâAlkyne Cycloaddition Reaction
A robust
method for constructing 1,4-pyrazoles from arylglycines
was developed using the copper-catalyzed sydnoneâalkyne cycloaddition
reaction. The procedure offers a straightforward and general route
to the pyrazole heterocycle through a three-step one-pot procedure
PET/Fluorescence Imaging: An Overview of the Chemical Strategies to Build Dual Imaging Tools
International audienceMolecular imaging is a biomedical research discipline that has quickly emerged to afford the observation, characterization, monitoring, and quantification of biomarkers and biological processes in living organism. It covers a large array of imaging techniques, each of which provides anatomical, functional, or metabolic information. Multimodality, as the combination of two or more of these techniques, has proven to be one of the best options to boost their individual properties, hence offering unprecedented tools for human health. In this review, we will focus on the combination of positron emission tomography and fluorescence imaging from the specific perspective of the chemical synthesis of dual imaging agents. Based on a detailed analysis of the literature, this review aims at giving a comprehensive overview of the chemical strategies implemented to build adequate imaging tools considering radiohalogens and radiometals as positron emitters, fluorescent dyes mostly emitting in the NIR window and all types of targeting vectors
Mise en place d'un modÚle de cancer pulmonaire orthotopique pour la validation méthodologique par ImmunoTEP
International audienceLes cancers bronchiques non Ă petites cellules (CBNPC) reprĂ©sentent environ 75 Ă 80 % des cancers bronchiques.La prise en charge personnalisĂ©e du cancer nĂ©cessite lâutilisation de biomarqueurs prĂ©dictifs de lâefficacitĂ© thĂ©rapeutique. Il est donc nĂ©cessaire de caractĂ©riser le microenvironnement tumoral de maniĂšre globale, câest Ă dire corps entier, via lâimagerie par immuno-TEP qui regroupe la Tomographie par Emission de Positons (TEP) et lâutilisation dâanticorps. Cependant le dĂ©veloppement de nouvelles mĂ©thodologies par immuno-TEP dans le CBNPC nĂ©cessite dâutiliser des modĂšles prĂ©cliniques reprĂ©sentatifs du microenvironnement tumoral.Nous avons pour cela, dĂ©veloppĂ© et caractĂ©risĂ© deux modĂšles tumoraux syngĂ©niques orthotopiques de CBNPC pour Ă©valuer leur microenvironnement tumoral : (i) un premier modĂšle via une implantation transpulmonaire et un second modĂšle via une implantation sus-pleurale dâune lignĂ©e CBNPC murine. La lignĂ©e cellulaire choisie est la lignĂ©e CMT167, un carcinome pulmonaire de souris mĂ©tastatique. La souche dâorigine de cette lignĂ©e est la C57BL/6 NRj. AprĂšs analgĂ©sie et anesthĂ©sie de la souris, la voie a dâabord Ă©tĂ© rĂ©alisĂ©e sur le plan thoracique gauche de lâanimal afin dâavoir accĂšs au poumon gauche monolobĂ©. Lâinjection des cellules que ce soit au niveau de la plĂšvre ou au niveau pulmonaire a Ă©tĂ© rĂ©alisĂ©e via une aiguille de 34G. La prise et la croissance tumorale ont Ă©tĂ© Ă©valuĂ©es par imagerie TEP avec le radioligand mĂ©tabolique couplĂ© Ă la TomoDensitoMĂ©trique (TDM). Le TEP-TDM permet de fixer des points dâarrĂȘts en Ă©valuant notamment la progression tumorale, en veillant Ă ne pas induire une dĂ©tresse respiratoire. Ceci permet Ă©galement de rĂ©duire le nombre dâanimaux en ayant une rĂ©elle connaissance de la prise tumorale au cours du temps et dâĂ©viter des euthanasies dâanimaux nâayant pas eu de prise tumorale.Quatre semaines post-injection, les tumeurs ont atteint un volume de ~150 mm3. Les tumeurs ont Ă©tĂ© prĂ©levĂ©es pour analyser le microenvironnement tumoral par immunofluorescence (PD-L1 et CD8 notamment). Lâinjection suspleurale permettrait dâobtenir un microenvironnement tumoral plus localisĂ© et plus reproductible entre diffĂ©rents groupes dâanimaux. Des rĂ©sultats complĂ©mentaires sont en cours dâacquisition pour diffĂ©rencier les deux modĂšles, notamment lâimmunoTEP ciblant PD-L1
New fluorine-18 pretargeting PET imaging by bioorthogonal chlorosydnoneâcycloalkyne click reaction
International audienceA PET pretargeting approach using strain-promoted sydnoneâalkyne cycloaddition
Copper(I)-Catalyzed Cycloaddition of 4âBromosydnones and Alkynes for the Regioselective Synthesis of 1,4,5-Trisubstituted Pyrazoles
Copper-catalyzed
cycloaddition of alkynes with 4-bromosydnones
provides a convenient, mild, and regioselective method for the synthesis
of a wide range of bromopyrazoles. The broad functional group tolerance
of the cycloaddition reaction and further palladium-catalyzed cross-coupling
reactions allowed the preparation of polyfunctionalized 1,4,5-pyrazoles
that are otherwise difficult to obtain by conventional methods