Mechanistic Aspects of Asymmetric Transfer Hydrogenation Catalyzed by 8 and 9 Group Transition Metal Complexes Bearing Diamine Ligands:Reactions and Properties of Formate and Alkoxide Complexes

摘要

A well-defined ruthenium amide complex,Ru[kappa~2(N,N')-(5,5)-TsNCHPhCHPhNH](p-cymene) (Ts = p-toluenesulfonyl,Ph = C_6H_3),readily reacts with HCOOH to give the formate complex,which subsequently undergoes decarboxylation leading to the hydride complex.On the other hand,the reaction of the amide complex with CF_3CH_2OH gives the novel metallacycles.The isoelectronic complex, Cp~*Ir[kappa~2(N,N')(S,S)-TsNCHPhCHPhNH] (Cp~* pentamethylcyclopentadienyl),also forms a metallacycle under same conditions.NMR studies suggest that this cyclometallation possibly proceeds through the corresponding alkoxide complexes as important intermediates.