Palladium Nanoclusters in Sonogashira Cross‐Coupling: A True Catalytic Species?

Thathagar, Mehul B.; Kooyman, Patricia J.; Boerleider, Romilda; Jansen, Eveline; Elsevier, Cornelis J.; Rothenberg, Gadi

doi:10.1002/adsc.200505229

Cited by 95 publications

(57 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[39][40][41] The leaching mainly occurs in reactions at high temperatures or carried out under extreme conditions, such as C-C coupling, Heck reaction, etc.. Taking into account this important phenomenon, we tried to reduce the leaching problems from our catalysts to a minimum level.…”

Section: -38mentioning

confidence: 99%

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

Ruiz¹,

Fierro²,

Reyes³

2010

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

A hidrogenação enantiosseletiva de piruvato de etila e de 1-fenil-1,2-propanodiona foi estudada a 298 K e sob 40 bar de H 2 sobre um catalisador de platina coloidal estabilizado com cinchonidina (CD) e suportado em sílica. O catalisador foi preparado por impregnação da platina coloidal em sílica, atingindo 1% em massa do metal no suporte. O colóide foi preparado a partir de uma solução aquosa de H 2 PtCl 6 estabilizada com diferentes quantidades de CD. O catalisador foi caracterizado por isotermas de adsorção-desorção de N 2 a 77 K e por XPS, XRD e TEM. As reações foram efetuadas em batelada em um reator de aço inoxidável, usando cicloexano como solvente e cinchonidina como modificador quiral. A adição de CD ao catalisador permite a estabilização e o controle do tamanho de partícula da platina, e também afeta o excesso enantiomérico (ee) do sistema, levando a um maior rendimento do produto com configuração R. A relação entre a concentração de CD adicionada in situ e a enantiosseletividade apresenta uma curva do tipo sino nas duas reações estudadas; este comportamento é um indicativo da importância da adsorção competitiva do modificador e do substrato na superfície do catalisador.The enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione was studied at 298 K and 40 bar of H 2 over colloidal Pt stabilized with cinchonidine (CD) and supported on silica. The catalysts were prepared by impregnation of colloidal Pt on SiO 2 , leading to a metal load close to 1 wt.%. The colloid was prepared from an aqueous solution of H 2 PtCl 6 and stabilized with different quantities of CD. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, XPS, XRD and TEM techniques. The reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. The addition of CD to the catalysts allows the stabilization and control of the platinum particle size and also affects the enantiomeric excess (ee) of the system, affording a higher proportion of the (R)-product. The relationship between the enantioselectivity and the CD concentration (added in situ) exhibits a bell type curve for both reactions, this being indicative of the importance of a competitive adsorption of the modifier and substrate on the catalyst surface.Keywords: Pt colloids, enantioselectivity, ethyl pyruvate, 1-phenyl-1,2-propanedione, cinchonidine IntroductionEnantioselective hydrogenation reactions are important tools to obtain fine chemicals used in pharmaceutical and food products.1-4 Thus, the synthesis of chiral compounds is of growing interest; among them, the hydrogenation of a-ketoesters and ketones is the most widely studied. [5][6][7][8][9][10][11][12][13][14][15] Since Orito et al. reported the enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate over cinchonidine-modified Pt catalysts with ee's up to 95%, many other research teams have evaluated the performance of their catalytic systems in this reaction. [16][17][18] Indeed, this is n...

show abstract

Section: -38mentioning

confidence: 99%

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

Ruiz¹,

Fierro²,

Reyes³

2010

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4] Sonogashira coupling is an important example of such chemistry, a prototypical case being the cross-coupling of phenylacetylene with iodobenzene (Scheme 1). When catalyzed by silica-supported Au nanoparticles, detailed evaluation of reaction data and quantitative analysis of the solid and solution phases by XPS and ICP-MS, respectively, led to the conclusion that the reaction was overwhelmingly a heterogeneous process with Au(0) metal clusters providing the active sites.…”

mentioning

confidence: 99%

Identity of the Active Site in Gold Nanoparticle-Catalyzed Sonogashira Coupling of Phenylacetylene and Iodobenzene

2010

View full text Add to dashboard Cite

XPS, TEM, and reaction studies were used to examine the catalytic behavior of gold species deposited on lanthana toward the cross-coupling of phenylacetylene and iodobenzene. Atomically dispersed Au I and Au III were catalytically inert, whereas metallic Au 0 nanoparticles were both active and very selective. Thus it is metallic gold and not ionic gold that provides the catalytically active sites. Au 0 nanoparticles supported on silica, γ-alumina, and BaO were active but relatively unselective; however, as with lanthana, ceria-supported Au 0 nanoparticles showed high selectivity. This strong promoting effect of the lanthanide oxide supports on Sonogashira selectivity cannot be accounted for in terms of acid/base, redox, or SMSI effects; it may be tentatively ascribed to metal f support hydrogen spillover.

show abstract

“…There are several reports on palladium-catalyzed reactions in ILs 50,51 such as Stille, 52 Suzuki, 53 SonogashiraHigihara, 54 Heck arylations 55,56 etc.…”

Section: Palladium-catalyzed Reactions In Ionic Liquidsmentioning

confidence: 99%

Ionic liquids: a versatile medium for palladium-catalyzed reactions

Singh¹,

Sharma²,

Mamgain³

et al. 2008

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Um grande número de reações de formação de ligações carbono-carbono (tais como: acoplamentos de Heck, Suzuki, Stille, Negishi e Sonogashira, entre outros) é facilitado pela catálise com compostos de paládio. Neste artigo de revisão, apresentamos uma visão detalhada e compreensiva da literatura sobre a versatilidade do uso de líquidos iônicos em conjunto com paládio em vários tipos de reações.A number of carbon-carbon bond forming reactions in organic chemistry (such as the Heck, Suzuki, Stille, Negishi, Sonogashira coupling etc) are facilitated by catalysis with palladium compounds. An attempt has been made to present a detailed and comprehensive literature collection about the versatility of ionic liquid in conjunction with palladium for various types of reactions.

show abstract

Palladium Nanoclusters in Sonogashira Cross‐Coupling: A True Catalytic Species?

Cited by 95 publications

References 28 publications

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

Identity of the Active Site in Gold Nanoparticle-Catalyzed Sonogashira Coupling of Phenylacetylene and Iodobenzene

Ionic liquids: a versatile medium for palladium-catalyzed reactions

Contact Info

Product

Resources

About