[Cp*Ru]-catalyzed selective coupling/hydrogenation

International audienc

C–C Bond Formation on Activation of Alkynes and Alkenes with (C5R5)Ru Catalysts

International audienceElectron-rich ruthenium(II) catalysts of type (C5R5)XRuL n are used to perform selective carbon–carbon bond formation by combination of simple substrates such as the coupling of functional alkynes and alkenes with a variety of unsaturated molecules (alkynes, diynes, alkenes, dienes) or non-unsaturated molecules such as alcohols or water, often with atom economy. Various selective transformations are developed and can provide access to high multifunctional molecules. These reactions often proceed via an initial oxidative coupling leading to a ruthenacycle intermediat

Caracterização da fauna acompanhante na pescaria de arrasto de tangone dirigida a camarões no litoral sul do Brasil

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2012.No mundo todo, estima-se que 10 milhões de toneladas de fauna acompanhante sejam descartadas na pesca de arrasto de camarões anualmente, representando cerca de 1/3 do descarte mundial. Tendo em vista que as artes de pesca utilizadas na pesca de camarões capturam incidentalmente uma grande quantidade de espécies e que causam grandes perturbações nos fundos arrastados, estudos sobre o impacto ecológico destas atividades devem ser desenvolvidos. Sabe-se que no litoral do Rio Grande do Sul, no inicio da década de 90, a fauna acompanhante da pescaria de tangones para camarão era de 23% e capturava principalmente Cynoscion guatucupa e Urophycis brasiliensis, peixes de grande interesse comercial. Com a sobrepesca de algumas espécies, as pescarias tiveram suas espécies-alvo modificadas, quando as capturas de espécies alternativas como Artemesia longinaris e Pleoticus muelleri tornaram-se bastante comuns na plataforma interna do sul do Brasil. O presente estudo teve por objetivo caracterizar e quantificar a fauna acompanhante da pescaria de arrasto de tangones para camarão no litoral sul do Brasil e suas variações durante as diferentes épocas do ano. As amostragens ocorreram a bordo de barcos da frota pesqueira com observadores científicos em duas viagens e através de coleta no momento do desembarque no setor industrial. Estudos sobre a fauna acompanhante na região são escassos, sendo necessárias informações sobre essas capturas, a fim de criar medidas de manejo para essas pescarias reduzindo o impacto que ocorre nesses ecossistemas

One-Step Ruthenium-Catalysed Transformation of 1,7-Enynes into Strained Bicyclic Amino Esters

International audienceThe reaction of 1,7-enynes, synthesised from α-amino acids, carried out with diazo compounds in the presence of the Cp*RuCl(cod) catalyst allowed the one-step preparation of various strained bicyclic pipecolic acid derivatives in good yields under mild conditions. The stereoselectivity of the created double bond depends on the nature of the diazoalkane, and the diastereoselectivity arises essentially from steric factors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Catalyse asymétrique au laboratoire de travaux pratiques : Synthèse d'un alcol chiral à partir de réactifs courants.

National audienc

Ruthenium-Catalyzed C–C Bond Formation

Molecular ruthenium catalysts are now currently used to perform selective carbon– carbon bond formation by combination of simple substrates. Their tolerance toward functional groups has allowed the access to high value,multifunctional molecules. It will be shown that ruthenium catalysts allow the coupling of functional alkenes or alkynes with a variety of unsaturated molecules such as alkenes, dienes, alkynes, and diynes. A large range of electron-rich ruthenium or hydridoruthenium complexes are currently used for the formation of cyclic and polycyclic compounds on reaction with substrates containing several unsaturated C–C bonds. Ruthenium complexes have promoted several original activation pathways, such as C–H bond activation, the distribution of carbene from diazoalkanes, and especially their versatility in making a large variety of ruthenacycle intermediates. Besides the applications of ruthenium precatalysts in organic synthesis an important discussion of and mechanisms will be presented

Cp*RuCl(COD) in Catalysis : a Unique Role in the Addition of Diazoalkane Carbene to Alkynes

International audienceThe catalytic transformations of functional alkynes with diazoalkanes in the presence of the catalyst precursor RuCl(COD)Cp* are presented. They show the unique role played by the Ru(X)Cp* moiety in catalysis and that the nature of the formed products strongly depends on the alkyne functionality. Simple alkynes generate dienes via double diazoalkane carbene addition to the triple bond. Enynes with terminal triple bond lead to alkenyl bicyclo[x.1.0]alkanes, including bicyclic aminoacid derivatives. 1,6-enynes with disubstituted propargylic carbon produce in priority alkenyl alkylidene cyclopentanes. 1,6-Allenynes offer the direct access to alkenyl alkylidene bicyclo[3.1.0]hexanes. Propargylic carboxylates lead to conjugated dienes by coupling of the diazoalkane carbene with the alkyne terminal carbon and 1,2-shift of the carboxylate. All catalytic reactions can be explained by the initial formation of the 16 electron RuCl(double bond; length as m-dashCHR)Cp* moiety giving first a 2+2 cycloaddition with the alkyne triple bond