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Despite tremendous efforts towards the development of organocatalytic enantioselective Michael additions of nitroalkanes to α,β‐unsaturated carbonyl compounds, highly substituted electrophiles remain challenging. β‐Arylidene‐α‐ketolactones and α‐ketolactams are used as highly electrophilic Michael acceptors that afford the corresponding products in moderate to good yields, with high enantioselectivities.

International audience; The regioselectivity of molecular sieves-promoted oxidative three-component reaction between -ketoesters, aromatic o-diamines and acrolein, leading to pyrido[1,2-a]benzimidazoles, has been investigated by a combination of experimental and theoretical studies. Molecular sieves act both as heterogeneous catalyst and dehydrating agent and their role has been modeled in the theoretical approach. The modulation of the reactivity of the aromatic diamine partner as a function of the nature of the substituents of the aromatic ring and its influence on the regioselectivity of the reaction could be rationalized.

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; The progress in enantioselective organocatalysis have enabled efficient and highly stereoselective syntheses of cyclobutane derivatives, through (2 + 2) annulation reactions, overcoming the geometrical constraints inherent to these small cyclic molecules. More importantly, and taking advantage of their strain-releasing fragmentation, some cyclobutane derivatives, especially cyclobutanones and cyclobutenones, can now be regarded as versatile four-carbon atoms units amenable to the enantioselective construction of larger rings by (4 + n) annulation reactions to produce, five-, six-, seven-and eightmembered cyclic products. These recent developments concerning the enantioselective synthetic chemistry of cyclobutane derivatives under organocatalytic conditions are reviewed herein.

Tetrahydropyridines are important heterocycles present in many molecules of natural and non‐natural origins that exhibit a wide array of biological activities. With several sp3‐hybridized carbon atoms in their structure, they often include one or several stereogenic centers, whose control represents a great synthetic challenge. For the past two decades, enantioselective organocatalysis has developed as a very powerful strategy to perform the synthesis of enantioenriched compounds, including heterocycles. In this Microreview, we wish to provide the readers with a general overview about the organocatalytic strategies that have been used to achieve the preparation of diversified families of tetrahydropyridines, thereby providing elements of reflection for further developments.

International audience; A rapid synthesis of enantioenriched 2,3,4-trisubstituted tetrahydropyrans in good yields and stereoselectivities is reported. The first step is a domino organocatalytic reaction between ambident electrophilic and 1,4-bis-nucleophilic 1,2-ketoamides and 1,3-bis-electrophilic enals, leading to aza-oxa-bicyclo[3.2.1]octane. Then, the TiCl4/Et3SiH system ensures a chemoselective cleavage of the C−N bond and affords the desired trisubstituted tetrahydropyran in good yield and with conservation of the precursors optical purity. This final synthetic operation includes two consecutive oxocarbenium ion formation and reductions.

International audience; Alkyl 4,5-dihydrofuran-2-carboxylates can be efficiently ob- tained via an enantioselective organocatalyzed consecutive reaction between _-keto esters and (Z)-(2-chloro-2-nitroethenyl)benzenes. The overall sequence combines a (R,R)-TUC-catalyzed Michael addition with a DABCO-promoted intramolecular O-alkylation leading to the title products as single diastereomers with enantiomeric excesses from 86% up to 97%.

Micellar Keggin heteropolyacid catalysts were prepared using hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide—CTAB), 1-hexadecyl-pyridinium chloride, and Keggin heteropolyacids H3PMo12O40 and H4PMo11VO40 as precursors. Four catalysts were prepared (PMo12C16, PMo11VC16, PMo12C16Py, and PMo11VC16Py) and characterized by 31P NMR, FT-IR, XRD, SEM analysis and textural properties (SBET). The acidic characteristics of the catalysts were determined by potentiometric titration with n-butylamine. A series of bioactive 1,4-dihydropyridine derivatives such as nifedipine and nemadipine B were synthesized using these new materials, in a one-pot procedure in ethanol. This methodology requires a reaction time of 8 h, and a temperature of 78 °C to obtain good to excellent yields of 1,4-dihydropyridine derivatives. The micellar Keggin catalysts are insoluble in polar media, which allows easy removal of the reaction products without affecting their catalytic activity. The leaching test showed that they have an excellent stability and can be used five times as heterogeneous catalysts without appreciable loss of the catalytic activity. Using the same material, unsymmetrical 1,4-dihydropyridines such as nitrendipine can be obtained through a sequence of steps in very good yield (78 %). Fil: Palermo, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina Fil: Sathicq, Angel Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina Fil: Constantieux, Thierry. Institut Des Sciences Moléculaires de Marseille; Francia Fil: Rodriguez, Jean. Institut Des Sciences Moléculaires de Marseille; Francia Fil: Vazquez, Patricia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina Fil: Romanelli, Gustavo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina

International audience; A new strategy for the synthesis of optically active pyrrolo[ 1,4]benzo- diazepine-2,5-diones has been developed. The approach is based on an initial Michael addition of functionalized 1,2-ketoamides on nitroalkenes, with a reduction–double cyclization sequence leading to the desired substituted benzodiazepine.

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; The organocatalytic enantioselective conjugate addition of secondary β-ketoamides to α,β-unsaturated carbonyl compounds is reported. Use of bifunctional Takemoto’s thiourea catalyst allows enantiocontrol of the reaction leading either to simple Michael adducts or spirocyclic aminals in up to 99 % ee. The origin of the enantioselectivity has been rationalised based on combined DFT calculations and kinetic analysis. This study provides a deeper understanding of the reaction mechanism, which involves a predominant role of the secondary amide proton, and clarifies the complex interactions occurring between substrates and the catalyst.

A new strategy for the rapid synthesis of enantioenriched medium-sized-ring lactones was developed. The method combines the organocatalytic Michael addition of cycloalkane-1,3-diones to α,β-unsaturated aldehydes with a subsequent reductively initiated Claisen fragmentation, which allows access to 10- and 11-membered-ring lactones with 91 to >99 % ee.

International audience; α,β-Unsaturated acyl cyanides are key bis-electrophile substrates for successful domino enantioselective organocatalyzed Michael-intramolecular acylation domino sequences. This new reactivity has been applied to the synthesis of enantioenriched azaspiro[4,5]decanone ring systems by a formal [3+3]spiroannulation, constituting a rare example of synthesis of glutarimides in an optically active form.

Three is a lucky number: An enantioselective transformation of allylic alcohols into β-chiral saturated alcohols has been developed by combining two distinct metal- and organocatalyzed catalytic cycles. This waste-free triple cascade process merges an iron-catalyzed borrowing-hydrogen step with an aminocatalyzed nucleophilic addition reaction.

Polysubstituted chiral cyclohexanes and cyclohexenes are important building blocks in organic synthesis. From historical and pioneering reports to the most recent accounts, this review focuses on domino enantioselective organocatalytic methodologies that have allowed the control of the relative and absolute configurations of up to six stereogenic centers in the construction of these versatile molecular architectures. 1 Introduction 2 Two-Component Transformations 2.1 Michael-Initiated Domino Reactions with α,β-Unsaturated Carbonyl Compounds 2.2 Michael-Initiated Domino Reactions with Nitroolefins 2.3 Non Michael-Initiated Domino Reactions 3 Multicomponent and Related Transformations 3.1 Pseudo-Three-Component Reactions 3.1.1 Michael-Initiated Domino Reactions with Nitroolefins 3.1.2 Michael-Initiated Domino Reactions with α,β-Unsaturated Carbonyl Compounds 3.2 Consecutive Reactions 3.2.1 Michael-Initiated Domino Reactions with Nitroolefins 3.2.2 Michael-Initiated Domino Reactions with α,β-Unsaturated Carbonyl Compounds 3.3 Multicomponent Reactions 3.3.1 Michael-Initiated Domino Reactions with Nitroolefins 3.3.2 Michael-Initiated Domino Reactions with α,β-Unsaturated Carbonyl Compounds 4 Conclusion

A metal-free and completely regioselective three-component synthesis of highly functionalized pyridines from 1,3-dicarbonyl derivatives and Michael acceptors has been achieved. Activated Michael acceptors, that is, β,γ-unsaturated α-oxo carbonyl derivatives, were utilized, allowing substitution at the 4-position and remarkable functional diversity at the 2-position of the pyridine ring. The scope and limitations of this environmentally friendly domino reaction are disclosed, with full experimental data, and the results of mechanistic investigations are discussed.

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.

A convenient and general preparative approach for tartrate-derived organic salts with bulky non-coordinating cations is described. This route is based on neutralisation of tartaric acid with cation hydroxides in aqueous solution. A series of 24 tartrate salts was prepared by systematic variation of the hemi- or bis-tartrate anion and the nature of the organic cation. Chirality of the anion was also explored as a vector for structural modification. Complete characterisation, including X-ray crystallography, was carried out. This comparative study of the physicochemical properties of these salts led to the identification of several informative trends useful for designing proper tartrate-based chiral ionic liquids.

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; A detailed study of the enantioselective borrowing hydrogen functionalization of allylic alcohols has allowed us to improve our understanding of the reaction parameters affecting both rate and enantiocontrol. This subsequently led to the identification of a triple catalysis combination of iron catalysts, copper catalysts, and organocatalysts. By this cooperative action among three distinct activation modes, a wide variety of allylic alcohols have been functionalized in improved typical 90% ee, providing rapid access to crucial synthetic building blocks.

A general evaluation of silylated nucleophiles to intercept transient α-oxoketenes generated by microwave-assisted Wolff rearrangement of 2-diazo-1,3-dicarbonyl compounds is presented. Original scaffolds and synthetic intermediates are accessed in a rapid, efficient and easy-to-handle way. Mechanistic studies by DFT calculations and some post-functionalizations are discussed.

Suitably substituted enantioenriched 4-aryl-1,4-dihydro-pyridines prepared by an organocatalytic enantioselective Michael addition were oxidized with MnO2 into axially chiral 4-arylpyridines with central-to-axial chirality conversion. Moderate to complete percentages (cp) were observed, and a model for the conversion of chirality is discussed.

International audience; Synthetic applications of cyclobutanones other than ring expansion and fragmentation reactions are rare. Herein, highly efficient diastereo- and enantioselective organocatalytic Michael additions of 2-substituted cyclobutanone derivatives to nitroalkenes are reported allowing the stereocontrolled creation of " all-carbon " quaternary centers. The approach relies on both the use of Brønsted base/hydrogen-bond donor bifunctional organocatalysts, and importantly, the specific stabilization and activation of cyclobutanone with a secondary amide moiety. The reaction was found to nicely accommodate a broad scope of substrates, allowing the control of up to three contiguous stereogenic centers. This work has opened new synthetic opportunities.

International audience; We designed a new, user-friendly oxidative dual heterogeneous catalytic system capable of promoting polysubstituted pyridines as unique products from simple activated Michael acceptors, 1,3-dicarbonyls and ammonium acetate. This metal-free environmentally-respectful and totally regioselective domino reaction proved to be a great strategy to access bi- and tri-aryl type pyridines as well as challenging bi- and tri-heteroaryl type pyridines in a single operation.

International audience; The efficiency of a chemical synthesis can be nowadays measured, not only by parameters like selectivity and overall yield, but also by its raw material, time, human resources and energy requirements, as well as the toxicity and hazard of the chemicals and the protocols involved. The development of multicomponent reactions (MCRs) in the presence of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also as catalysts, is a new approach that meet with the requirements of sustainable chemistry. The aim of this tutorial review is to highlight the synergistic effect of the combined use of MCRs and ILs for the development of new eco-compatible methodologies for heterocyclic chemistry.

International audience; A general evaluation of silylated nucleophiles to intercept transient α-oxoketenes generated by microwave-assisted Wolff rearrangement of 2-diazo-1,3-dicarbonyl compounds is presented. Original scaffolds and synthetic intermediates are accessed in a rapid, efficient and easy-to-handle way. Mechanistic studies by DFT calculations and some post-functionalizations are discussed.

A new strategy for the rapid synthesis of enantioenriched medium-sized-ring lactones was developed. The method combines the organocatalytic Michael addition of cycloalkane-1,3-diones to α,β-unsaturated aldehydes with a subsequent reductively initiated Claisen fragmentation, which allows access to 10- and 11-membered-ring lactones with 91 to >99 % ee.

The three-component reaction of β-keto esters, enals, and amines affords two different types of products depending on the presence of a substituent in the α-position of the aldehyde.

A new strategy for the synthesis of optically active pyrrolo[1,4]benzodiazepine-2,5-diones has been developed. The approach is based on an initial Michael addition of functionalized 1,2-ketoamides on nitroalkenes, with a reduction–double cyclization sequence leading to the desired substituted benzodiazepine.

International audience; Suitably substituted enantioenriched 4-aryl-1,4-dihydro-pyridines prepared by an organocatalytic enantioselective Michael addition were oxidized with MnO2 into axially chiral 4-arylpyridines with central-to-axial chirality conversion. Moderate to complete conversion percentages (cp) were observed, and a model for the conversion of chirality is discussed.

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.

The organocatalytic enantioselective conjugate addition of secondary β-ketoamides to α,β-unsaturated carbonyl compounds is reported. Use of bifunctional Takemoto’s thiourea catalyst allows enantiocontrol of the reaction leading either to simple Michael adducts or spirocyclic aminals in up to 99 % ee. The origin of the enantioselectivity has been rationalised based on combined DFT calculations and kinetic analysis. This study provides a deeper understanding of the reaction mechanism, which involves a predominant role of the secondary amide proton, and clarifies the complex interactions occurring between substrates and the catalyst.

We report the first enantioselective organocatalyzed domino synthesis of azepane moieties. This temporary-bridge strategy is based on a conceptually original annulation of ambident electrophilic and 1,4-bis-nucleophilic α-ketoamides with 1,3-bis-electrophilic enals. The obtained oxygen-bridged azepanes can be selectively transformed into optically active azepanone, azepanol or azepanedione derivatives of high synthetic value.

The totally diastereoselective synthesis of new P-stereogenic (o-hydroxyaryl)diazaphospholidines, in the form of their borane complexes 4a–4h, is described. The efficiency of this procedure is based both, on a one-pot and totally diastereoselective synthesis of the precursors (ortho-bromoaryloxy)diazaphosphospholidine–borane complexes 3a–3h, and on a stereoselective P–O to P–C migration rearrangement. A X-ray diffraction study of the structures of the product 4f and his precursor 3f shows unambiguously the totally stereoselectivity of the P–O to P–C rearrangement with clean retention of the phosphorus configuration.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Although isocyanide-based multicomponent reactions (MCRs), introduced in 1921 by Passerini, largely predominate nowadays in the construction of widely diverse heterocycles, one of the first substrate classes involved in a MCR was that of 1,3-dicarbonyl derivatives, with Hantzsch’s dihydropyridine synthesis appearing as early as 1882. The aim of this microreview is to present an overview of the great synthetic potential of MCRs involving the specific reactivity of easily accessible 1,3-dicarbonyl derivatives and to stress their more recent utilisation for the development of new and useful methodologies valuable for the selective construction of highly functionalised small organic molecules of high synthetic and biological value. After a short general introduction, we present chronologically the different methodologies developed on the bases of the reactivity of 1,3-dicarbonyl systems towards many other substrates involved in a variety of synthetic pathways, including Knoevenagel condensations, Michael and Mannich reactions, cyclodehydrations, electrocyclisations, cycloadditions and metal-promoted transformations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Michael addition of 1,3-dicarbonyls with various Michael acceptors has been found to be catalyzed by commercially available, user-friendly and recyclable N-phenyl-tris(dimethylamino)iminophosphorane immobilized on polystyrene resin (P-BEMP). The reaction does not require anhydrous solvents or inert atmosphere and proceeds smoothly at room temperature leading to the corresponding adducts, which can be conveniently isolated in high yield and with high chemical purity by simple filtration.

Solid acid catalysts based on the direct incorporation of the vanadium Keggin heteropolyacid (PMo11V) structure during the synthesis of silica by the sol–gel technique, in acidic media using tetraethyl orthosilicate (PMo11VSiO21, PMo11VSiO22, PMo11VSiO23, and PMo11VSiO24), were prepared and characterized by 31P-NMR, FT-IR, XRD, and textural properties (SBET). The acidic characteristics of the catalysts were determined by potentiometric titration with n-butylamine. A series of highly substituted hexahydropyrimidines were synthesized using these new materials, encapsulated in a silica framework, as catalyst in solvent-free conditions. This methodology requires short reaction time (1.5 h), a temperature of 80 °C in solvent free-conditions to obtain good to excellent yields of trifluoromethyl-hexahydropyrimidine derivatives. The Keggin catalyst embedded in the silica matrix is insoluble in polar media, which allows easy removal of the reaction products without affecting their catalytic activity., Centro de Investigación y Desarrollo en Ciencias Aplicadas

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.

Optimized conditions including a chiral squaramide catalyst render possible the conjugate addition of β-ketoamides to nitroolefins to give the corresponding products with high diastereoselectivities and excellent enantioselectivities.

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.

Functionalized γ-chiral alcohols are prepared via an unprecedented cascade reaction which combines dual iron—amine-catalyzed enantioselective functionalization of allylic alcohols and chemoselective acyl transfer.