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Olefin Ligand (olefin + ligand)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Stereochemical Control by an Ester Group or Olefin Ligand in Platinum-Catalyzed Carboalkoxylation of 6-(1-Alkoxyethoxy)- hex-2-ynoates

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009
Itaru Nakamura
Abstract The cyclization of 6-(1-alkoxyethoxy)hex-2-ynoantes in the presence of the platinum-olefin catalyst system gave the corresponding multisubstituted 2-[dihydrofuran-2(3H)-ylidene]acetates in good to high yields. The Z/E selectivity is controlled by the electronic property of the ester group; the 2,2,2-trichloroethyl ester yielded the Z isomer, while the phenyl ester gave the E isomer. Moreover, we found that the Z/E selectivities in the reaction of phenyl esters 1h, 1n, and 1o were controlled by the olefin ligand. For example, the platinum-catalyzed reaction of 1h using 1,5-hexadiene as the olefin ligand gave E - 2h as the major product, while that using 1,5-cyclooctadiene produced mainly the Z isomer. [source]

ChemInform Abstract: Stereochemical Control by an Ester Group or Olefin Ligand in Platinum-Catalyzed Carboalkoxylation of 6-(1-Alkoxyethoxy)-hex-2-ynoates

CHEMINFORM, Issue 38 2009
Itaru Nakamura
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Chiral Phosphine,Olefin Ligands in the Rhodium-Catalyzed Asymmetric 1,4-Addition Reactions.

CHEMINFORM, Issue 24 2007
Wei-Liang Duan
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Stereochemical Control by an Ester Group or Olefin Ligand in Platinum-Catalyzed Carboalkoxylation of 6-(1-Alkoxyethoxy)- hex-2-ynoates

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009
Itaru Nakamura
Abstract The cyclization of 6-(1-alkoxyethoxy)hex-2-ynoantes in the presence of the platinum-olefin catalyst system gave the corresponding multisubstituted 2-[dihydrofuran-2(3H)-ylidene]acetates in good to high yields. The Z/E selectivity is controlled by the electronic property of the ester group; the 2,2,2-trichloroethyl ester yielded the Z isomer, while the phenyl ester gave the E isomer. Moreover, we found that the Z/E selectivities in the reaction of phenyl esters 1h, 1n, and 1o were controlled by the olefin ligand. For example, the platinum-catalyzed reaction of 1h using 1,5-hexadiene as the olefin ligand gave E - 2h as the major product, while that using 1,5-cyclooctadiene produced mainly the Z isomer. [source]

Olefins as Steering Ligands for Homogeneously Catalyzed Hydrogenations

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2004
Pascal Maire
Abstract Iridium(I) complexes containing a (5H -dibenzo[a,d]cyclohepten-5-yl)-phosphane (troppR; R = phosphorus-bound substituent = Ph, Cyc) as a rigid, concave-shaped, mixed phosphane olefin ligand were prepared and tested as catalyst precursors in the hydrogenation of imines. With the complex [Ir(troppCyc)(cod)]OTf, turnover frequencies (TOFs) of >6000 h,1 were reached in the hydrogenation of N -phenyl-benzylidenamine, PhNCHPh. Lower activities (TOF>80 h,1) are observed with N -phenyl-(1-phenylethylidene)amine, PhNCMePh. Chiral tropp-type ligands were prepared in few simple steps. Monosubstitution of the olefinic unit in the dibenzo[a,d]cycloheptenyl moiety with (R)- or (S)-mentholate gave mixtures of diastereomers that could be separated and isolated in enantiomerically pure form. Iridium(I) complexes with these ligands are rare examples of side-on bonded enolether complexes. In catalytic imine hydrogenations, complete conversion (>98,%) was reached in all cases (conditions: p[H2] = 50 bar, T = 50,°C, t = 2 h, substrate/catalyst 100:1). The best enantiomeric excess (ee = 86,% S isomer) was reached with PhNCMePh as substrate and the R,R form of the (10-menthyloxy-5H -dibenzo[a,d]cyclohepten-5-yl)diphenylphosphane ligand. The iridium(I) complex containing the same phosphane gave a 60,% ee (S isomer) with the enamide N-(1-phenylvinyl)acetamide as substrate (conditions: p[H2] = 4 bar, T = 50,°C, t = 18 h, substrate/catalyst = 50:1). These reactions constitute the first examples in which chiral olefins have been used as steering ligands in catalytic enantioselective hydrogenations. [source]