Ligands, ruthenium

BITIANP, were tested as ruthenium ligands for the asymmetric hydrogenation of various olefinic substrates. The results collected in Scheme 8.8 show that these novel ligands were able to induce high enantioselectivities of up to 94% ee. ... 

Fig. 22. Reduction of 63 with various ruthenium amino alcohol complexes attached to the primary face of p-CD yield and ee of the resulting alcohol is given below the ruthenium ligand.

Kenneth J. Takeuchi received his BS degree summa cum laude from the University of Cincinnati in 1975 and his PhD degree in chemistry from Ohio State University in 1981. He spent two years at the University of North Carolina at Chapel Hill conducting postdoctoral research in chemistry. In 1983, he accepted a position as assistant professor of chemistry at the State University of New York at Buffalo he was granted tenure and promoted to associate professor in 1990 and promoted to professor in 1998. Professor Takeuchi was a consultant with ARCO Chemical for five years and has been a consultant with Greatbatch, Inc. for the past five years. He is an author or coauthor of 75 refereed articles and more than 140 presentations at various scientific meetings. His areas of research include coordination chemistry of ruthenium, ligand effects on transition metal chemistry, electrochemistry, materials chemistry, and battery related chemistry. 

Ruthenium(II) complexes may also be used to oxidize N-Boc hydroxylamine in the presence of tert-butylhydroperoxide (TBHP) to the corresponding nitroso dieno-phile, which is subsequently trapped by cyclohexa-1,3-diene to give the hetero Diels-Alder adduct (Entry 1, Scheme 10.26) [51]. A triphenylphosphine oxide-stabilized ruthenium(IV) oxo-complex was found to be the catalytically active species. Use of a chiral bidentate bis-phosphine-derived ruthenium ligand (BINAP or PROPHOS) result in very low asymmetric induction (8 and 11%) (Entry 2, Scheme 10.26). The low level of asymmetric induction is explained by the reaction conditions (in-situ oxidation) that failed to produce discrete, stable diastereomerically pure mthenium complexes. It is shown that ruthenium(II) salen complexes also catalyze the oxidation of N-Boc-hydroxylamine in the presence of TBHP, to give the N-Boc-nitroso compound which can be efficiently trapped with a range of dienes from cyclohepta-1,3-diene (1 h, r.t., CH2CI2, 71%) to 9,10-dimethylanthracene (96 h, r.t., CH2CI2,... 

One compound which did not work well in our system was our original model, a-phenylacrylic acid. A number of these aryl propionic acids are valuable as nonsteroidal antiarthritics. Here, as is typically the case, only one enantiomer is active and thus a process to prepare one isomer directly was needed. We tried hard to solve this problem, even using ruthenium-ligand systems, but without success. It took Professor Noyori with his BINAP-ruthenium complex to solve this problem [4]. This is just another example in the history of invention. The one who makes the first discovery seldom makes the second. On a grander stage, this may explain why there are so few double Nobel Laureates. 

Other atropisomeric phosphines 3.45 have been recommended as ligands in rhodium-catalyzed asymmetric hydrogenations of prochiral a,[3-unsaturated acids or esters [892, 904] when R = c-CgHj or in rhodium-catalyzed asymmetric isomerization of allylamines 3.44 [905] when R = Ph. These phosphines 3.45 (R = Ph or c- CgHj j) are interesting ruthenium ligands in asymmetric hydrogena-... 

Rate constants, k, are for electron transfer from the donor to acceptor groups in ruthenated electron transfer proteins. Ruthenium ligands are abbreviated as follows NH3, a isonicotinamide, isn pyridine, py. MP are metallosubstituted porphyrins (M = Fe, Zn, Pd, Pt, Mg, Cd, and H), MP and MP- + are the photoexcited and oxidized radical cation forms of MP, respectively. PDE is porphyrin diester, d is the closest edge-to-edge distance between cofactor atoms. 

Ruthenium/ligand ratio taking into account the total amount of ligand present in the reaction, from the synthesis of colloid with the extra ligand added to the catalytic reaction. Substrate conversion and ee determined by GC using a chiral column. 

Iron and Ruthenium.— Ligand-exchange reactions of ferrocene with anthracenes and phenanthrenes have afforded cationic r-arene complexes in which one or both of the terminal arene rings are complexed with a CpFe+ residue and in which the central arene ring is either unchanged or ciSyCndo-... 

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