36002-44-5Relevant academic research and scientific papers
Atom Economic Ruthenium-Catalyzed Synthesis of Bulky β-Oxo Esters
Jeschke, Janine,Korb, Marcus,Rüffer, Tobias,G?bler, Christian,Lang, Heinrich
supporting information, p. 4069 - 4081 (2016/01/25)
Ruthenium complexes with the formulae Ru(CO)2(PR3)2(O2CPh)2 [6a-h; R=n-Bu, p-MeO-C6H4, p-Me-C6H4, Ph, p-Cl-C6H4, m-Cl-C6H4, p-CF3-C6H4, m,m′-(CF3)2C6H3] were prepared by treatment of triruthenium dodecacarbonyl [Ru3(CO)12] with the respective phosphine and benzoic acid or by the conversion of Ru(CO)3(PR3)2 (8e-h) with benzoic acid. During the preparation of 8, ruthenium hydride complexes of type Ru(CO)(PR3)3(H)2 (9g, h) could be isolated as side products. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 6a-h were found to be highly effective catalysts in the addition of carboxylic acids to propargylic alcohols to give valuable β-oxo esters. The catalyst screening revealed a considerably influence of the phosphine′s electronic nature on the resulting activities. The best performances were obtained with complexes 6g and 6h, featuring electron-withdrawing phosphine ligands. Additionally, catalyst 6g is very active in the conversion of sterically demanding substrates, leading to a broad substrate scope. The catalytic preparation of simple as well as challenging substrates succeeds with catalyst 6g in yields that often exceed those of established literature systems. Furthermore, the reactions can be carried out with catalyst loadings down to 0.1mol% and reaction temperatures down to 50 C.
A combined parahydrogen and theoretical study of H2 activation by 16-electron d8 ruthenium(0) complexes and their subsequent catalytic behaviour
Dunne, John P.,Blazina, Damir,Aiken, Stuart,Carteret, Hilary A.,Duckett, Simon B.,Jones, Jonathan A.,Poli, Rinaldo,Whitwood, Adrian C.
, p. 3616 - 3628 (2007/10/03)
The photochemical reaction of Ru(CO)3(L)2, where L = PPh3, PMe3, PCy3 and P(p-tolyl)3 with parahydrogen (p-H2) has been studied by in-situ NMR spectroscopy and shown to result in two competing processes. The first of these involves loss of CO and results in the formation of the cis-cis-trans-L isomer of Ru(CO)2(L)2(H)2, while in the second, a single photon induces loss of both CO and L and leads to the formation of cis-cis-cis Ru(CO)2(L)2(H)2 and Ru(CO)2(L) (solvent)(H)2 where solvent = toluene, THF and pyridine (py). In the case of L = PPh3, cis-cis-trans-L Ru(CO)2(L) 2(H)2 is shown to be an effective hydrogenation catalyst with rate limiting phosphine dissociation proceeding at a rate of 2.2 s -1 in pyridine at 355 K. Theoretical calculations and experimental observations show that H2 addition to the Ru(CO)2(L) 2 proceeds to form cis-cis-trans-L Ru(CO)2(L) 2(H)2 as the major product via addition over the π-accepting OC-Ru-CO axis.
Systematic substituent effects on dissociative substitution kinetics of Ru(CO)4L complexes (L = P-, As-, and Sb-donor ligands)
Chen, Lezhan,Po?, Anthony J.
, p. 3641 - 3647 (2008/10/08)
The kinetics of dissociation of CO from Ru(CO)4L (L = a wide variety of P-, As-, and Sb-donor ligands) have been studied, and the values of the rate constants can be resolved quantitatively into electronic and steric effects. The curved steric profile obtained shows that steric effects are quite small for small substituents such as P(OCH2)3CEt and P(OEt)3, but they increase steadily and substantially as the size of the substituent increases. A similar analysis of data in the literature for CO dissociative reactions of other substituted carbonyl complexes is also successful in resolving electronic and steric effects, and a clear dependence of steric effects on the coordination number of the complexes is shown. The analysis can be applied to some methyl migration reactions that involve CO loss, and the results can help to indicate the relative importance of CO loss and methyl migration in the transition states. Trends in the C-O stretching frequencies in the axial Ru(CO)4L and diaxial Ru(CO)3L2 complexes are described.
