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International audience; A reinvestigation of a chiral phosphoric-acidcatalyzedfour-component Hantzsch enantioselective synthesis of polyhydroquinolines reported in 2009 is presented. In our hands, when the reaction was performed with fidelity to the original report using a chiral enantiopure phosphoric acid catalyst, noenantioselectivity was observed. Unlike in the original report,enantioselectivity results are backed by baseline separation of the enantiomers by HPLC analyses on chiral stationary phase with UV and chiroptical detection.

International audience; Azaphosphatranes were found to act as efficient organocatalysts in the presence of water for the cyanation of differently substituted imines. A relatively safer source of cyanide, trimethylsilyl cyanide (TMSCN), was used, and excellent yields could be obtained with only 0.05 mol % of catalyst. The influence of acidity of azaphosphatranes on catalytic activity as well as the role of azaphosphatranes in the mechanism of the reaction were also investigated.

β-Dicarbonyl compounds have established themselves as substrates of choice in enantioselective organocatalysis because of their easy activation. Among them, β-diketones, β-diesters, and β-ketoesters lead the dance and there has been only limited work with other β-dicarbonyl compounds as pronucleophiles. In this Synpacts article, we wish to discuss our recent contributions to the introduction of Weinreb β-ketoamides in organocatalyzed transformations, where they can provide an interesting balance between reactivity and selectivity, with also interesting potentialities in terms of postfunctionalization.1 Introduction2 Preparation of Weinreb β-Ketoamides3 Michael Addition to Nitroolefins4 Multicomponent Synthesis of Tetrahydropyridines5 Outlook

International audience; For the first time, enantiomerically enriched atropoisomeric furans have been accessed using a central- to-axial chirality conversion strategy. Hence, oxidation of the enantioenriched dihydrofuran precursors gave rise to axially chiral furans with high enantiopurities accounting from excellent conversion percentages (cp) in most cases.

In this feature article, a general perspective of the research program aimed towards the preparation of polycyclic heterocycles by the means of enantioselective organocatalytic multicomponent reactions is presented. Guidelines for reaction design, including the selection of substrates and organocatalysts are discussed. For all transformations, scope and limitations are presented, along with post-functionalization to afford diversified heterocyclic scaffolds. 1 Introduction 2 Type I Products: 1,4,5,6-Tetrahydropyridines 3 Type II Products: 1,2,3,4-Tetrahydropyridines 4 Type III Products: Bridged Perhydropyridines 5 Conclusion and Perspective

International audience; The reaction between cyclic 1,3-ketoamides and Michael acceptors in the presence of a catalytic amount of a polymer-supported organobase PS-BEMP has been developed for a direct access to spirocyclic 1,3-ketolactams through a domino Michael addition/hemiacetalization sequence. The products could be isolated in high chemical yields and purities after simple filtration, and the catalyst could be re-used without any re-activation. These spirolactams, containing a hemiaminal moiety, may be viewed as precursors of N-acyliminium intermediates upon Lewis acid activation, which allowed various subsequent functionalizations leading to original polycyclic lactams.

International audience; The results on the multicomponent reaction between cyclic β-keto esters, enals, and simple primary aliphatic amines are reported. In thermal conditions in the presence of 4 Å molecular sieves, two different¬ families of heterocyclic products (aminobicyclo[3.3.1]nonanones or cycloalka[b]piperidines) were obtained depending on the presence of a substituent in the α-position of the aldehyde. Moreover, preliminary results on the possibility to obtain these two bicyclic cores from the very same starting materials by introducing organocatalysts with different activation modes in the reaction are presented.

International audience; We have developed the first multicomponent synthesis of enantioenriched polycyclic 1,2,3,4-tetrahydropyridines bearing three contiguous stereogenic centers under iminium activation. The key to the success of this reaction was the use of polyfunctional substrates including 2-aminophenols and scarcely used β-ketoamides triggering a thermodynamically controlled regio- and diastereoselective sequence.

International audience; Comprehensive and up-to-date, this book focuses on the latest advances in the field, such as newly developed techniques, more environmentally benign processes, broadened scopes, and completely novel MCRs.

International audience; Our findings on the bifunctional squaramide-catalyzed enantioselective conjugate addition of β-ketoamides to nitroolefins are disclosed. It appears that simple acyclic methylene β-ketoamides, unlike the extensively studied β-ketoesters, afford the products in excellent diastereoselectivities, and maintain high yields and enantioselectivities. Moreover, competition and kinetic studies were conducted to rationalize the observed reactivity and selectivity. The high level of diastereocontrol, along with the amenability of the amide group to postfunctionalization, dramatically increase the synthetic usefulness of the transformation.

International audience; The first organocatalytic multicomponent synthesis of enantioenriched pyrrolopiperazines is reported. These biologically relevant fused tricyclic products were obtained under catalytic iminium activation through a reaction sequence involving an enantioselective Michael addition followed by an iminium ion trapping via Pictet-Spengler cyclization (MAPS sequence). Substantial possibilities for variation on the three reaction partners [β-keto ester, enal and N-(2-aminoethyl)pyrrole] along with excellent enantioselectivities are the highlights of the present transformation.

International audience; Several reactive sites of 1,2- and 1,3-ketoamides were successively exploited in two complementary domino transformations for the synthesis of polysubstituted monocyclic or bridged bicyclic cyclohexanes, with the creation of up to six stereogenic centers. In both cases, a chiral bifunctional thiourea organocatalyst allowed efficient control of chirality in the final carbocycle.

An innovative access to a β,β-disubstituted Morita–Baylis–Hillman motif, which is a potential intermediate en route to the synthesis of the aglycon of landomycins, is presented. It consists of a finely optimized organocuprate-initiated domino Michael–intramolecular aldol reaction. The use of TMSCl and DMAP as additives proved essential to ensure the success of this reaction sequence.

International audience; Faster, higher, stronger! The N-heterocyclic carbene (NHC) catalyzed diastereo- and enantioselective hydroacylation of cyclopropenes affords structurally valuable acylcyclopropanes. A new family of electron-rich, 2,6-dimethoxyphenyl-substituted NHCs induces excellent reactivity and enantioselectivity. Preliminary kinetic studies unambiguously demonstrated the superiority of this family of catalysts over known NHCs in this challenging transformation.

International audience; The synthesis of the highly functionalized tetracyclic skeleton of landomycinone (2), the aglycon of landomycins, was performed using two pivotal steps relying on metal-catalyzed reactions. They are (1) a [2 + 2 + 2] cycloaddition of alkynes promoted by Wilkinson's catalyst to build rings B and C concomitantly and (2) a ring-closing metathesis followed by aromatization to build ring D.

Original and ambivalent: We describe the preparation of a series of new potassium trifluoroborates 1, and the study of their behaviour in a Pd0-catalyzed cross-coupling reaction. We found that compounds 1 are endowed with original properties as they behave as nucleophilic cross-coupling partners chemoselectively, but also as ambivalent synthons. The usefulness of this methodology has been successfully illustrated by the first total synthesis of an N-acyl spermidine. We describe the preparation of a series of new potassium trifluoroborates 1 and the study of their behaviour in a Pd0-catalyzed cross-coupling reaction. We found that compounds 1 are endowed with original properties as they behave as nucleophilic cross-coupling partners chemoselectively but also as ambivalent synthons. The usefulness of this methodology has been successfully illustrated by the first total synthesis of an N-acyl spermidine.

In this study, we focus on the Azaphosphatranes derivatives: studies on their halogen-bond donor properties, their behaviors as confined Frustrated Lewis/Bronsted Pairs and their chiral recognition properties. Firstly, we synthesized the chloroazaphosphatranes with various substituent groups, and discussed their binding constants. Then we synthesized two hemicryptophanes which contain rigid cavities, we discussed the inherent chirality and the reactivity outcome. Last, we synthesized two other hemicryptophanes to discuss their recognition properties toward neurotransmitters, and also we focus on the thermodynamic and kinetic studies, we finally calculated the value of pKa, and the rate constants. Besides, we discussed a true FLP system in the presence of TiCl4., Dans cette étude, nous nous concentrons sur les dérivés d'Azaphosphatranes : études sur leurs propriétés de donneurs de liaisons halogènes, leurs comportements en tant que paires de Lewis/Bronsted frustrées confinées et leurs propriétés de reconnaissance chirale. Tout d'abord, nous avons synthétisé les chloroazaphosphatranes avec différents groupes substituants, et discuté de leurs constantes de liaison. Ensuite, nous avons synthétisé deux hémicryptophanes qui contiennent des cavités rigides, nous avons discuté de la chiralité inhérente et des résultats de la réactivité. Enfin, nous avons synthétisé deux autres hémicryptophanes pour discuter de leurs propriétés de reconnaissance envers les neurotransmetteurs, et nous nous sommes également concentrés sur les études thermodynamiques et cinétiques, nous avons finalement calculé la valeur du pKa, et les constantes de vitesse. En outre, nous avons discuté d'un véritable système FLP en présence de TiCl4.

This thesis focuses on the development of enantioselective multicomponent reactions with 1,3-Dicarbonyls in the presence of an organocatalyst, to synthesize fused polyheterocyclic motives.At first, we describe our initial results on an enantioselective multicomponent reaction with enals and simple primary amines. In view of the low enantioselectivities achieved, functionalized amines were then introduced in these reactions, thereby synthesizing enantioenriched pyrrolopiperazines and other polyfunctionalized heterocyclic molecules, all obtained with attractive yields and high enantioselectivities.Having successfully used methylene β-Ketoamides in these enantioselective MCRs, we realized also that their simple Michael addition to electron-Poor olefins had never been described in organocatalytic conditions. We therefore studied their reaction with nitroolefins in the presence of various chiral organocatalysts, and the expected products were pleasingly obtained with high yields, excellent diastereo- and enantioselectivities.; Ce mémoire de thèse se concentre sur le développement de réactions multicomposants énantiosélectives de dérivés 1,3-Dicarbonylés en présence d'un organocatalyseur, en vue de préparer des motifs polyhétérocycliques fusionnés.Dans un premier temps, nous décrivons nos résultats initiaux sur une réaction multicomposants énantiosélective avec des énals et des amines primaires simples. Au vu des faibles énantiosélectivités obtenues, des amines fonctionnalisées ont ensuite été introduites dans ces réactions, permettant ainsi de synthétiser des pyrrolopiperazines et d'autres molécules hétérocycliques polyfonctionnalisées énantioenrichies, toutes obtenues avec des rendements intéressants et des énantiosélectivités élevées.Ayant utilisé avec succès des β-Cétoamides α-Méthyléniques dans ces réactions multicomposantes, nous avons réalisé par ailleurs que leur simple addition de Michael sur des oléfines pauvres en électrons n'avait jamais été décrite en version organocatalysée. Nous avons donc étudié leur réaction avec des nitrooléfines en présence d’organocatalyseurs chiraux, et les produits attendus ont alors été obtenus avec de bons rendements et d'excellentes diastéréo- et énantiosélectivités.