131152-80-2Relevant articles and documents
Kinetics and mechanism of catalysis of the asymmetric hydrogenation of α,β-unsaturated carboxylic acids by Bis(carboxylato){2,2′-bis(diphenylphosphino)-1,1′-binaphthyl}- ruthenium(II), [RuII(BINAP)(O2CR)2]
Ashby, Michael T.,Halpern, Jack
, p. 589 - 594 (2007/10/02)
The rate law for the hydrogenation of α,β-unsaturated carboxylic acids in methanol, catalyzed by bis(carboxylato){(R)-or (S)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl}ruthenium(II) ([RuII(BINAP)(O2CR)2]), at near ambient conditions and in the absence of added product, has the following form: rate = kobs[Ru]T[substrate][H2]/[substrate] 0. The rate law and the results of labeling studies support the conclusion that the catalytically active species in the turnover-limiting step of the reaction is a substrate-containing bis(carboxylato)ruthenium complex that splits H2 heterolytically to form a metal hydride. Subsequent insertion of the C = C bond of the coordinated substrate yields a five-membered heterometallacyclic species; protonolysis of the resulting Ru-C bond gives the final product. The catalytic rate is very sensitive to the presence of strong acid; slightly more than 1 equiv (with respect to catalyst) of triflic acid inhibits hydrogenation completely. In contrast, the rate of hydrogenation is unaffected by base. The enantiomeric excess, greater than 90% when the substrate is tiglic acid, is unaffected by addition of acid or base.
