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International audience; AbstractVarious catalytic reactions under suitable conditions were used for the carbon-carbon (C-C) bond formation, such as the Kumada, Mizoroki-Heck, Sonogashira, Negishi, Stille, Suzuki-Miyaura, Hiyama, andFukuyama cross-coupling reactions. Supporting metal nanoparticles or complexes on functionalizedgraphene oxide (GO) or reduced graphene oxide (rGO) compounds provides new heterogeneous catalysts with enhanced aptitude for the formation of C-C bonds. This review highlights the applications ofmetal decorated on modified GO and rGO derivatives to form C-C bonds. We discuss briefly the generalmechanistic cycle of each reaction and the recent applications of the graphene-based nanocatalysts forthe coupling reactions, along the advantages of each catalyst.

In this comprehensive paper, three redox-neutral reactions, including [2 + 2] and [4 + 2] cycloadditions and vinylcyclopropane rearrangements, are outlined from the viewpoint of energy conversion. These reactions demonstrate the power of electrosynthesis in the field of synthetic organic chemistry not only from the viewpoint of energy conversion but also from that of redox economy because four-, five-, and six-membered-ring skeletons are constructed without a change in oxidation state of the growing molecules in synthetic routes. The key for all of the reactions is precise control of single-electron transfer (SET) in lithium perchlorate/nitromethane solution, where oxidative SET is facilitated and the thus-generated radical cations are highly stabilized. SET processes can be visualized by plotting the highest occupied molecular orbital and spin density distributions to obtain theoretical pictures for a mechanistic understanding of the reactions; the deduced mechanisms are in good accordance with the reactions’ formal expressions.

During last two decades, transition-metal catalyzed asymmetric reactions under continuous flow system have attracted a widespread attention. With its prominent advantages including higher safety and efficiency, precise control, better heat/mass transfer, easier scale-up and better sustainability, it has impressed both the academia and related industries. However, comparing with the prosperous development of transition-metal catalyzed asymmetric reactions in batch, utilization of this type of chemistry under continuous flow is still at an early stage. To inspire more potential industrial application and further studies of this chemistry in flow, this review summarized the recent advances of transition-metal catalyzed asymmetric reactions under continuous flow. Moreover, we further discussed the encountered challenges including reactor engineering, catalyst design, catalyst deactivation, pressure drop, clogging, side reactions etc., as well as their corresponding solutions and achievements in this mini-review.

Deep eutectic solvents (DESs), surmised as “the organic reaction medium of the century”, have reverberated a new symphony throughout the present green millennium. A brief historical account of the DES systems and their physicochemical properties as task-specific and designer solvents for cross-coupling reactions are appraised including the hole theory that explains the underlying mechanistic pathway for this emerging neoteric medium. The insights into cross-coupling reactions and their applications are included, highlighting the significant achievements pertaining to the dual role of DESs as a solvent and catalyst. In addition, popular “name-reactions” for the carbon–carbon and carbon–heteroatom bond formations related to the nature of DESs and the core optimum conditions are included. The review also encompasses the novel approaches to privileged catalytic systems and identify the voids left in cross-coupling reactions where DES systems have not made inroads yet. Finally, the challenges of utilizing the neoteric derivatives of DES for these reactions are expounded. S. E. H. and R. A. are grateful to the Iran Science Elites Federation (ISEF). D. J. R. gratefully acknowledges financial support from the Spanish Ministerio de Economía, Industria y Competitividad (PGC2018-096616-B-100) and University of Alicante (VIGROB-316FI).

One of the most important name reactions in organic chemistry, is the Diels-Alder cycloaddition reaction. It is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile to construct a substituted cyclohexene derivative. It is the stereotypical example of a pericyclic reaction with a concerted mechanism. In synthesis, the use of electricity instead of stoichiometric amounts of oxidant or reducing agents is definitely appealing for economic, ecological and selective, reasons. In this review, we try to underscore the combination of the electrosynthesis with Diels-Alder cycloaddition reaction to establish of a powerful synthetic tool which may encourage synthetic organic chemists to use it in the future.

Suzuki-Miyaura Coupling Reaction (SMCR) has been extensively used in the total synthesis of natural products. We underscored these achievements in a report published in Tetrahedron up to 2012. Since then, there has been tremendous growth in this field and numerous articles have been published after 2012. In this review, we tried to go insight and highlight the current developments in the applications of SMCR as a key and strategic step (steps) in the total synthesis of biologically active natural products accomplished and reported from 2012 till date.

The palladium-catalyzed reaction of aryl halide and boronic acid for the formation of C–C bonds so-called Suzuki–Miyaura cross-coupling reaction has many applications in Modern Synthetic Organic Chemistry. In 2013, we emphasized the applications of the intramolecular Suzuki cross-coupling reaction in cyclization and heterocyclization. Due to a plethora relevant papers appeared in the chemical literature, herein, we wish to cover by updating our previous review, the applications of the intramolecular Suzuki cross-coupling reaction in cyclization and heterocyclization leading to various homocyclic and heterocyclic compounds reported during a period of 2013 to 2018.

Asymmetric aldol addition of simple aldehydes and ketones to electrophiles is a cornerstone reaction for the synthesis of unusual sugars and chiral building blocks. We investigated D-fructose-6-phosphate aldolase from E. coli (FSA) D6X variants as catalysts for the aldol additions of linear and cyclic non-functionalized aliphatic ketones or ethanal as nucleophiles to non-phosphorylated hydroxyaldehydes. Thus, addition of propanone, cyclobutanone, cyclopentanone or ethanal to 3-hydroxypropanal or (S)- or (R)-3-hydroxybutanal catalyzed by FSA D6H and D6Q variants furnished rare deoxysugars in 8-77% isolated yields with high stereoselectivity (97:3 dr and >95% ee). © 2018 American Chemical Society., This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 635595 (CarbaZymes), the Ministerio de Economía y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (FEDER) (grant CTQ2015-63563-R to P.C. and CTQ2015-64436-P to T.P.), COST action CM1303 Systems Biocatalysis and funding from the Auvergne council.

Despite of their chemical instability and high reactivity, conjugated nitrosoalkenes are useful intermediates in target-oriented organic synthesis. The present review deals with carbon–carbon bond forming reactions involving Michael addition to α-nitrosoalkenes with a particular focus on recent developments in this methodology and its use in total synthesis.

International audience; In the context of the depletion of fossil resources, formaldehyde is an emerging C-1 source exhibiting high and versatile reactivity, in comparison to the most studied C-1 molecules (CO2, CO, HCOOH, and CH4). In the present mini-review, we show that biocatalysis is an ideal approach to control the reactivity of formaldehyde and to use its great potential as a platform for the synthesis of value-added chiral products. The ability of aldolases and ThDP-dependent enzymes to catalyze stereocontrolled carbon-carbon bond formation with formaldehyde are shown to involve aldol and umpolung reactivity. The synergetic combination of (i) enzyme discovery, (ii) mechanistic understanding, and (iii) enzyme engineering provides highly stereospecific biocatalysts of increasing interest for synthetic chemistry.

IBM and PAW would like to thank the EPSRC and CRITICAT Centre for Doctoral Training for Financial Support [PhD studentship to IBM, and supplementary equipment grant EP/L016419/1]. The UK Catalysis Hub is thanked for resources and support provided via membership of the UK Catalysis Hub Consortium and funded by EPSRC (grants EP/I038748/1, EP/I019693/1, EP/K014706/1, EP/K014668/1, EP/K014854/1, EP/K014714/1 and EP/M013219/1). We thank the Diamond Light Source for provision of beam time and support facilities at the MIRIAM beamline B22 (Experiments SM13725-1, SM16257-1, SM18680-1, SM20906-1). Synchrotron infrared microspectroscopy has identified with high temporal resolution (down to 0.25 s) the initial events occurring when methanol vapor is in contact with a crystal of zeolite HZSM-5. The first alkenes are generated directly from methoxy groups formed at the acid sites via their deprotonation. These alkenes can either desorb directly or oligomerize and cyclize to form dimethylcyclopentenyl cations. The oligomeric and dimethylcyclopentenyl cations are the first major components of the hydrocarbon pool that precede aromatic hydrocarbons and lead to indirect alkene formation. The technique observes these events in real time. Postprint Postprint

The formation of the C–C bond is a major and important reaction in synthetic organic chemistry and frequently catalyzed by transition-metal catalysts. Among them, Kumada–Tamao–Corriu coupling reaction is providing a simple methodology and extensively employed in the art of organic synthesis. In this review, we try to highlight the recent advances in the applications of Kumada–Tamao–Corriu coupling reaction by updating of our previous review from 2012 up to date.

Cascade polyene cyclization reactions are highly efficient and elegant bioinspired transformations that involve simultaneous multiple bond constructions to rapidly generate complex polycyclic molecules. This review summarizes the most prominent work on a variety of cationic and radical cascade cyclizations and their applications in natural product synthesis published between 2014 and 2018.1 Introduction2 Cationic Polyene Cyclizations2.1 Lewis Acid Mediated Polyene Cyclizations2.2 Brønsted Acid Mediated Polyene Cyclizations2.3 Halogen Electrophile Initiated Polyene Cyclizations2.4 Sulfur Electrophile Initiated Polyene Cyclizations2.5 Transition-Metal-Mediated Cationic Polyene Cyclizations3 Radical Polyene Cyclizations3.1 Transition-Metal-Mediated Radical Polyene Cyclizations3.2 Photocatalyst-Mediated Polyene Cyclizations4 Origin of Stereocontrol in Polyene Cyclizations5 Conclusion

Background: The reaction of aryl halides or vinyl halides with activated alkenes in the presence of Palladium-catalyst along with a base for the formation of the C-C bond is called the Heck reaction. This reaction has been employed extensively in the synthesis of heterocyclic compounds. Methodology: We have highlighted these applications in 2010. Conclusion: This review aims to cover the recent application of the Heck reaction in the synthesis of heterocyclic compounds during a period from 2010 to 2017. Dedicated to my dearest “ TEEDA” on the occasion of her third birthday.

In this account, our studies on radical reactions that are promoted by dimethylzinc and air are described. Advantages of this reagent and differences from conventional radical initiators, such as triethylborane, are discussed., Article first published online: 17 JUL 2015

Citrate synthase from the thermophilic euryarchaeon T. acidophilum fused to a hexahistidine tag was purified and biochemically characterized. The structure of the unliganded enzyme at 2.2 Å resolution contains tail–active site contacts in half of the active sites., Citrate synthase (CS) plays a central metabolic role in aerobes and many other organisms. The CS reaction comprises two half-reactions: a Claisen aldol condensation of acetyl-CoA (AcCoA) and oxaloacetate (OAA) that forms citryl-CoA (CitCoA), and CitCoA hydrolysis. Protein conformational changes that ‘close’ the active site play an important role in the assembly of a catalytically competent condensation active site. CS from the thermoacidophile Thermoplasma acidophilum (TpCS) possesses an endogenous Trp fluorophore that can be used to monitor the condensation reaction. The 2.2 Å resolution crystal structure of TpCS fused to a C-terminal hexahistidine tag (TpCSH6) reported here is an ‘open’ structure that, when compared with several liganded TpCS structures, helps to define a complete path for active-site closure. One active site in each dimer binds a neighboring His tag, the first nonsubstrate ligand known to occupy both the AcCoA and OAA binding sites. Solution data collectively suggest that this fortuitous interaction is stabilized by the crystalline lattice. As a polar but almost neutral ligand, the active site–tail interaction provides a new starting point for the design of bisubstrate-analog inhibitors of CS.

Carbon-carbon bond formations and deoxygenation reactions are important for biomass up-grading. The classical ketonic decarboxylation of carboxylic acids provides symmetrical ketones with 2n+1 carbon atoms and eliminates three oxygen atoms. Herein, this reaction is carried out with titanium oxide at 400 degrees C, and an olefin with 2n + 1 carbon atoms is obtained instead of the ketone. For olefin formation hydrogen transfer reactions are required from suitable precursors to form aromatics and coke. Additional aldol condensation reactions increase further molecular weight in the product mixture. Hence, a combination of titanium oxide with a hydrodeoxygenation bed provides double amount of diesel fuel as the combination with zirconium oxide when reacting hexose-derived pentanoic acid., The authors thank MINECO (MAT2011-28009, Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and Severo Ochoa program, SEV-2012-0267), Generalitat Valenciana (PROMETEOII/2013/011 Project), and the Spanish National Research Council (CSIC, Es 2010RU0108). B.O.-T. is grateful to the CSIC (JAE Programme) for his Ph.D. fellowship.

Submitted by ANA CAROLINA DE TOLEDO SANTANA null (actoledo@iq.unesp.br) on 2016-03-17T17:25:32Z No. of bitstreams: 1 Dissertação Carol Final.pdf: 7825510 bytes, checksum: 921c29706ed56e5ef489712bae28fc30 (MD5) Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-03-21T20:10:04Z (GMT) No. of bitstreams: 1 santana_act_me_iq_par.pdf: 4512361 bytes, checksum: 07a7dc911b2bdd27db8608948a16848b (MD5) Made available in DSpace on 2016-03-21T20:10:04Z (GMT). No. of bitstreams: 1 santana_act_me_iq_par.pdf: 4512361 bytes, checksum: 07a7dc911b2bdd27db8608948a16848b (MD5) Previous issue date: 2016-02-26 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) O presente trabalho teve como principal objetivo estudar a atividade catalítica de soroalbumina bovina (BSA) em reações formadoras de uma nova ligação C-C: Reações aldólica, de Henry e Morita-Baylis-Hillman (MBH). Em todos os casos a BSA atuou como catalisador, visto que quando as reações foram realizadas sem sua presença, não houve formação dos produtos desejados. Os rendimentos obtidos para as reações aldólica (37%), Henry (80%) e MBH (73%), variaram de bons a moderados e não foi observada enantiosseletividade para nenhuma das reações estudadas. As soroalbuminas são proteínas que formam muita emulsão dificultando os processos downstream na separação dos produtos e materiais de partida. Visando minimizar este inconveniente, a BSA foi submetida à imobilização em MCLEA (magnetic cross-linking enzyme aggregates) utilizando nanopartículas magnéticas de óxido de ferro. Nestes casos, o biocatalisador pôde ser facilmente retirado do meio reacional com aplicação de um campo magnético externo. Esta metodologia afetou diretamente no rendimento da reação de Henry, passando de 80% para 89%. Porém, para as outras reações a melhoria no rendimento não foi tão expressiva. A imobilização também não foi eficaz para o aumento dos excessos enantioméricos. Até o momento para a reação de MBH com os substratos utilizados, não há relatos na literatura para a síntese do aduto desejado catalisado pela BSA. Sendo assim, optamos por realizar um planejamento fatorial completo dessa reação visando otimizar as condições reacionais bem como os rendimentos. As variáveis estudadas foram: temperatura, concentração do biocatalisador e condição do biocatalisador (livre ou imobilizado). Os resultados obtidos mostraram que a variável com maior influência na reação, é a concentração do biocatalisador. A conversão obtida passou de 30% para 40% utilizando 2,2 μmol de BSA. Em seguida, realizamos um estudo de ascendência da concentração do catalisador visando otimizar este parâmetro. A conversão obtida passou para 73% quando foram utilizadas 3,7 μmol de biocatalisador imobilizado. Realizamos um estudo de reciclagem do biocatalisador imobilizado. Foi possível reutiliza-lo porém com diminuição da conversão a partir do segundo ciclo. Os resultados obtidos nesta dissertação evidenciam o potencial biocatalítico da BSA em reações para a formação de ligação C-C. This work aimed to study the catalytic activity of bovine serum albumin (BSA) in reactions that form a new C-C bond: aldol reactions, Henry and Morita-Baylis-Hillman (MBH). In all cases BSA served as the catalyst, whereas when the reactions were carried out without their presence there was no formation of the desired products. The yields obtained for aldol reactions (37%), Henry (80%) and MBH (73%), ranged from good to moderate enantioselectivity and was not observed for any of the studied reactions. The serum albumins are proteins that form the much emulsion difficulting downstream processes in separation of the products and starting materials. To minimize this inconvenience, the BSA was subjected to immobilization in M-CLEA (magnetic cross-linking enzyme aggregates) using magnetic nanoparticles of iron oxide. In these cases the biocatalyst could be easily removed from the reaction medium by applying an external magnetic field. This methodology directly affect the yield of the Henry reaction, from 80% to 89%. However, for other reactions the improvement of yields was less pronounced. The immobilization was also not effective for improving the enantiomeric excess. So far for the MBH reaction with the worked substrates, there are no reports in the literature for the synthesis of the desired adduct catalyzed by BSA. So we decided to study a full factorial design of this reaction to optimize the reaction conditions and yields. The variables studied were: temperature, the biocatalyst concentration and biocatalyst conditions (free and immobilized). The concentration of biocatalyst was the major factor with interference in all reactions. The conversion increased from 30% to 40% using 2.2 μmol of BSA. Then we perform a study of catalyst concentration to optimize this parameter. The conversion increased to 73% when they were used 3.7 μmol immobilized biocatalyst. To evaluate the retention of catalytic activity of BSA immobilized, it was performed a study of the immobilized biocatalyst recycling. It was possible the reuse but with reduced conversion from the second cycle. The results obtained in this work demonstrated the potential of BSA in C-C bond formation reactions.

The reactivity of C-CH3 substituted N-protected aldimines in aza-Henry addition reactions was compared with that of the analogous trifluoromethylated compounds. C-Alkyl aldimines easily reacted with nitro alkanes under solvent-free conditions and in the absence of catalyst, despite being worse electrophiles than C-CF3 aldimines, they gave the aza-Henry addition only when ZrCl4 was added. The presence of a bulky group on the imine carbon deeply influenced the reactivity.

The highly enantioselective synthesis of a- methyl-substituted esters is reported in up to 90% yield and up to 99% ee using copper-TaniaPhos as chiral catalyst. The transformation proved scalable to at least 6.6 mmol (1.7 g scale). The products of this transformation have been further elaborated to mul- tifunctional building blocks with a single (branched esters and acids) or multiple stereogenic centers (vi- cinal dimethyl esters, as well as, hydroxy- or iodo- substituted lactones).

This review focuses on the directed evolution of aldolases with synthetically useful properties. Directed evolution has been used to address a number of limitations associated with the use of wild-type aldolases as catalysts in synthetic organic chemistry. The generation of aldolase enzymes with a modified or expanded substrate repertoire is described. Particular emphasis is placed on the directed evolution of aldolases with modified stereochemical properties: such enzymes can be useful catalysts in the stereoselective synthesis of biologically active small molecules. The review also describes some of the fundamental insights into mechanistic enzymology that directed evolution can provide.

We report on a simple synthetic route to a novel anthracene-based bis-armed amino acid derivative as a useful fluorescent probe. Various photophysical studies of this amino acid derivative are also described. Here, Suzuki-Miyaura cross-coupling reaction has been used as a key step for carbon-carbon bond formation.

Results are reported on the efficiency of polyfluorooctanol as a perfluorousauxiliary component in the aldol reaction between the enolate derived frompolyfluorooctyl acetate and 2-fluorobenzaldehyde. Reduction of the correspondingpolyfluoro β-hydroxy ester with Super Hydride® gave the required 1,3-diol in good yield.

A strategic synthesis of novel methylpyrimidine sulfonyl piperazines involving Suzuki coupling was designed and pharmacological activities of the compounds were evaluated. Reactions were carried out under conventional method and show good functional group transformations and high yields. Structures of the newly synthesized compounds were established by infrared spectroscopy (IR), ¹H and 13C nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) and elemental analysis. The compounds were tested for in vitro antibacterial activity against Escherichia coli and Staphylococcus aureus bacterial strains, anthelmintic activity using Pheretima posthuma and anti-inflammatory activity involving carrageenan induced rat paw edema model. Some compounds were proven to be potent pharmacophores. Uma síntese estratégica de novas piperazinas sulfonil metilpirimidina envolvendo acoplamento Suzuki foi desenvolvida e as atividades farmacológicas dos compostos foram avaliadas. As reações foram realizadas pelo método convencional e apresentaram boas transformações dos grupos funcionais e elevados rendimentos. As estruturas dos novos compostos sintetizados foram estabelecidas por espectroscopia no infravermelho (IR), ressonância magnética nuclear (NMR) de ¹H e de 13C, e cromatografia líquida-espectrometria de massas (LC-MS) e análise elementar. Os compostos foram testados quanto à atividade antibacteriana in vitro contra as cepas bacterianas Escherichia coli e Staphylococcus aureus, à atividade antihelmíntica utilizando Pheretima posthuma e à atividade anti-inflamatória envolvendo o modelo de edema de pata de rato induzido pela carragena. Provou-se que alguns compostos são farmacóforos potentes.

A long-standing challenge in transition metal catalysis is selective C–C bond coupling of simple feedstocks, such as carbon monoxide, ethylene or propylene, to yield value-added products. This work describes efforts toward selective C–C bond formation using early- and late-transition metals, which may have important implications for the production of fuels and plastics, as well as many other commodity chemicals. The industrial Fischer-Tropsch (F-T) process converts synthesis gas (syngas, a mixture of CO + H2) into a complex mixture of hydrocarbons and oxygenates. Well-defined homogeneous catalysts for F-T may provide greater product selectivity for fuel-range liquid hydrocarbons compared to traditional heterogeneous catalysts. The first part of this work involved the preparation of late-transition metal complexes for use in syngas conversion. We investigated C–C bond forming reactions via carbene coupling using bis(carbene)platinum(II) compounds, which are models for putative metal–carbene intermediates in F-T chemistry. It was found that C–C bond formation could be induced by either (1) chemical reduction of or (2) exogenous phosphine coordination to the platinum(II) starting complexes. These two mild methods afforded different products, constitutional isomers, suggesting that at least two different mechanisms are possible for C–C bond formation from carbene intermediates. These results are encouraging for the development of a multicomponent homogeneous catalysis system for the generation of higher hydrocarbons. A second avenue of research focused on the design and synthesis of post-metallocene catalysts for olefin polymerization. The polymerization chemistry of a new class of group 4 complexes supported by asymmetric anilide(pyridine)phenolate (NNO) pincer ligands was explored. Unlike typical early transition metal polymerization catalysts, NNO-ligated catalysts produce nearly regiorandom polypropylene, with as many as 30-40 mol % of insertions being 2,1-inserted (versus 1,2-inserted), compared to

International audience; The selective formation of carbon–carbon bond by functionalization of an sp3C–H bond is still a challenge in organic synthesis. There are already examples involving transition metal catalysis. In this chapter we review the use of ruthenium(0) and ruthenium(II) catalysts for the formation of carbon–carbon bonds based on creation of reactive sites by sp3C–H bond activation. We show that in most cases, regioselective sp3C–H bond activation is induced either from functional substrates bearing a directing group, which strongly coordinates the metal centre, or by selective C–H bond activation at the α-carbon of a heteroatom accompanied by hydrogen transfer processes and transient creation of reactive functional groups

The development of efficient methods for the selective formation and cleavage of C-C bonds leading to construction of new carbon skeletons catalyzed by transition-metal complexes is a central and challenging subject of modern organic synthesis. Among the various transition-metal complexes, we have recently focused our attention on novel catalytic activity of low valent ruthenium complexes, since ruthenium complexes often show interesting catalytic activity and product selectivity, which are quite different from those with palladium and other transition-metal complexes. Here, we report our recent results of novel catalytic performance of ruthenium complexes for organic synthesis, which include (1) ruthenium-catalyzed novel C-C bond formation using an ambiphilic reactivity of π-allylruthenium complexes as well as the selective cleavage of C-C bonds via β-allyl elimination, (2) ruthenium-catalyzed novel methods for preparation of cyclopentenones via ruthenacycle intermediates, and (3) ruthenium-catalyzed novel transformation of sulfur-containing compounds, which enables simple, selective and general syntheses of vicinal-dithioethers and allylic sulfides.

Small gold clusters containing 3-6 atoms (submolar) catalyze different carbon-carbon and carbon-heteroatom bond-forming reactions. They can be formed in situ from gold salts, complexes and nanoparticles under acidic conditions. A sound determination of possible clusters in solution for previously reported reactions can only be assessed after accurate kinetic studies, in situ and ex situ spectroscopic measurements, and comparison with preformed gold clusters, as the stability of gold salts and complexes can vary depending on the type of catalyst and the experimental conditions. The results here reported could be expanded not only to other gold-catalyzed reactions but also to other catalytic metal systems., Financial support by the Severo Ochoa program and Consolider-Ingenio 2010 (proyecto MULTICAT) from Ministerio de Ciencia e Innovacion (MCIINN) is acknowledged. J. O.-M. thanks Instituto de Tecnologia Quimica (ITQ) for a postgraduate scholarship. A. L.-P. thanks Consejo Superior de Investigaciones Cientificas (CSIC) for a contract.

[EN] Essentially molecular rhodium catalysts were made from Rh(C2R4)(2)(acetylacetonate) on zeolite HY and on MgO and characterized by infrared and X-ray absorption spectroscopies. The supported rhodium species anchored to the zeolite, initially in the form of Rh(C2H4)(2), selectively catalyzed ethene dimerization, typically at 298 K and 1 bar, but when the catalyst was poisoned by CO, or the support was changed to MgO or zeolite NaY, or the rhodium was converted into small clusters, the ethene underwent predominantly hydrogenation. The preciseness of the synthesis of the supported rhodium species facilitated determination of structure-catalyst performance relationships that led to a schematic representation of how the dimerization proceeds by a mechanism involving both the rhodium complexes and zeolite surface OH groups. The reaction is facilitated by H-2 and proceeds as one ethene molecule is activated by an isolated rhodium complex and another by a weakly acidic Si-OH-Al group. (C) 2013 Elsevier Inc. All rights reserved., The research was supported by the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement PIOF-GA-2009-253129 (P.S.) and by DOE Basic Energy Sciences (FG02-04ER15513). We thank the DOE Division of Materials Sciences for its role in the operation and development of beam line 4-1 at the Stanford Synchrotron Radiation Lightsource. We thank the beam line staff for valuable support.

International audience; Triarylsulfonium salts are prompted to undergo efficient homolytic reduction by single electron transfer under mild photocatalytic conditions. The liberated aryl radical can then participate in carbon-carbon bond formation processes with allyl sulfones and activated olefins. Triarylsulfonium salts emerge as a valuable and alternative source of aryl radicals for synthesis.

This is an Open Access article under the terms of the Creative Commons Attribution License., The activity of gelatin and collagen proteins towards C-C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification influence product yield and kinetics, affording the nitroaldol products in both aqueous and organic media under mild conditions. Significantly, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane is successfully achieved at 1 g scale and in good yield. A comparative kinetic study with other biocatalysts shows an increase of the first-order rate constant in the order chitosan < gelatin < bovine serum albumin (BSA) < collagen. The results of this study indicate that simple edible gelatin can promote C-C bond forming reactions under physiological conditions, which may have important implications from a metabolic perspective. © 2013 Kühbeck et al; licensee Beilstein-Institut., This work was supported by the Universität Regensburg (Förderlinie C des Finanziellen Anreizsystems für Drittmitteleinwerbung), Ministerio de Ciencia e Innovación – FEDER (CTQ2010-17436), Gobierno de Aragón-FSE (research group E40). B.B.D. thanks CSIR for appointment as a Sr Research Associate (Scientist’s Pool Scheme).

Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems highly likely that the technology is or has been used for ton-scale production. We document twelve cases where the Mizoroki-Heck reaction was used to arylate an alkene. In two of these cases allylic alcohols were arylated, leading to the aldehyde or the ketone. The Suzuki reaction has been used mostly to produce biaryl compounds from aryl halides and arylboronic acid derivatives. Twelve processes were recorded. Ortho-tolyl-benzonitrile, a biaryl compound produced via the Suzuki reaction, is used as an intermediate in six different pharmaceuticals all belonging to the Sartan group of blood pressure-lowering agents. The Kumada-Corriu reaction in which an aryl or alkenyl Grignard is coupled to an aryl or alkenyl halide was used nine times. In these coupling reactions palladium is often replaced by the much cheaper nickel or iron catalysts. The Negishi reaction couples an arylzinc halide with an aryl or alkenyl halide. These reactions are fast and highly selective; the only drawback being the stoichiometric zinc waste. Two cases were found. In one of these it was possible to use only a catalytic amount of zinc (double metal catalysis). The Sonogashira reaction couples a terminal alkyne to an aryl or alkenyl halide. Three cases were found. Acetylene is usually not coupled as such in view of its instability. Instead, trimethylsilylacetylene or the acetylene acetone adduct is used. Finally, one case was found of a palladium-catalysed allylic substitution and one case of a CH-activation reaction to form a benzocyclobutane ring. Most of these reactions were implemented in production in the past ten years.

Conselho Nacional de Desenvolvimento Científico e Tecnológico This PhD thesis describes our results on the application of indium(I) bromide in carbon-carbon bond forming reactions. Indium enolates, generated in situ from the reaction between indium(I) bromide and α,α-dichloroketones, react with carbonyl compounds and electron-deficient alkenes. Reactions of indium enolate with α,α-dichloroketones, in presence of extra InBr, leads to the formation of 1,4-diketones. The coupling with aldehydes leads alternatively, according as the stoichiometry, to the diastereoselective synthesis of (syn+anti)-2-chloro-3-hydroxy-propan-1-ones (which can be converted to the respective trans-epoxyketones), (E)-α,β-unsaturated ketones and cyclopropanes, upon a sequenced reaction mechanism. We also have developed a methodology for the preparation of cyclopropanes through the reaction of the indium enolate and other organoindium(III) compounds, derived from the reactions between InBr and α,α-dihalo carbonyl compounds and halo-acetonitriles, with electron-deficient alkenes. Este trabalho descreve os resultados dos estudos realizados sobre aplicações de brometo de índio(I) em reações para formação de ligações carbono-carbono. A reação entre brometo de índio(I) e α,α-diclorocetonas produz, in situ, enolatos de índio que reagem com compostos carbonílicos e alcenos deficientes em elétrons. As reações do enolato de índio com outras moléculas de α,α-diclorocetonas, na presença de InBr em excesso, leva à formação de 1,4-dicetonas. O acoplamento com aldeídos leva alternativamente, conforme a estequiometria, à formação diastereosseletiva de (syn+anti)-α-cloro-β-hidróxi-cetonas (que podem ser convertidas às respectivas trans-epóxi-cetonas), cetonas (E)-α,β-insaturadas e ciclopropanos, segundo um mecanismo de reações sequenciais. Ainda foi desenvolvida uma metodologia para preparação de ciclopropanos através da reação do enolato de índio e de outros compostos organoíndio(III), derivados da reação entre InBr e vários compostos carbonílicos α,α-di-halogenados e halogeno-acetonitrilas, com alcenos deficientes em elétrons.

The chiral non racemic (Λ, R , R )-[OSSO]Zr(CH 2 Ph) 2 ( 1a ) activated by methylaluminoxane (MAO) and in presence of H 2 produces the chiral hydrodimer ( S )-1,3-diphenylbutane with good selectivity respect to the achiral 1,4-diphenylbutane. The absolute configuration of the chiral dimer and the effect of the hydrogen pressure on the ratio between 1,3-diphenylbutane and 1,4-diphenylbutane give useful information about the regiochemistry and stereochemistry of insertion of the styrene into the Zr–H bond.

In this short note, we report the synthesis of 6-methyl-2-nitro-1-phenyl-hept-4-en-3-ol by a LiAlH4 catalyzed nitroaldol reaction for carbon-carbon bond formation. The title compound was characterized by 1H-NMR, 13C-NMR, MS, IR and elemental analysis.

Aldolases are enzymes with potential applications in biosynthesis, depending on their activity, specificity and stability. In the present study, the genomes of Sulfolobus species were screened for aldolases. Two new KDGA [2-keto-3-deoxygluconate (2-oxo-3-deoxygluconate) aldolases] from Sulfolobus acidocaldarius and Sulfolobus tokodaii were identified, overexpressed in Escherichia coli and characterized. Both enzymes were found to have biochemical properties similar to the previously characterized S. solfataricus KDGA, including the condensation of pyruvate and either D,L-glyceraldehyde or D,L-glyceraldehyde 3-phosphate. The crystal structure of S. acidocaldarius KDGA revealed the presence of a novel phosphate-binding motif that allows the formation of multiple hydrogen-bonding interactions with the acceptor substrate, and enables high activity with glyceraldehyde 3-phosphate. Activity analyses with unnatural substrates revealed that these three KDGAs readily accept aldehydes with two to four carbon atoms, and that even aldoses with five carbon atoms are accepted to some extent. Water-mediated interactions permit binding of substrates in multiple conformations in the spacious hydrophilic binding site, and correlate with the observed broad substrate specificity.

Department of Chemistry, Wenzhou Normal College, Wenzhou 325027, P.R. China E-mail: hywu3@ 163.com Fax: 86-577-88339081 Manuscript received 9 April 2003, accepted 22 August 2003 Mediated by active metallic indium generated in situ from Sm/InCI3.4H2O bimetallic system, aldehydes and allylic bromide undergo efficient Barbier-type allylation reaction to afford homoallylic alcohols in high yields under mild conditions in aqueousmedia.

International audience; Heterogeneous enantioselective alkylation of benzaldehyde with diethylzinc was performed using (-)-ephedrine grafted on mesoporous micelle templated aluminosilicates or silicates, as chiral auxiliary. Supports were characterized by a regular mesoporosity and a same initial pore diameter. Immobilization of the chiral aminoalcohol was performed through covalent anchoring of 3-halogenopropyltrimethoxysilane (XPTMS) and substitution of the halogen by (-)-ephedrine. Comparison of the efficiency of the catalysts was carried out. Results were analyzed taking into account the accessibility to the catalytic sites by changing their density (decrease of XPTMS concentration, spacing of the sites by alkyl goups) and the effect of the uncovered mineral surface on activities and enantioselectivities.