New efficient methods for the synthesis and in-situ preparation of ruthenium(II) complexes of atropisomeric diphosphines and their application in asymmetric catalytic hydrogenations

Article abstract of DOI:10.1016/S0957-4166(00)82157-6

A new synthetically useful method for the synthesis of the diphosphine ruthenium dicarboxylato complexes (P-P)Ru(O₂CR)₂(R= CF₃ and CH₃) is presented, which uses the easily accessible complex (COD)₂Ru₂(μ-O₂CCF₃)₄ as starting material. This complex as well as (COD)(Ru(ηO₂CCH₃)₂ and (COD)₂Ru₂Cl₄(NCCH₃) have been shown to be suitable precursor complexes for the in-situ preparation of ruthenium(II) dicarboxylato and dichloro complexes of atropisomeric diphosphines, respectively. The high efficacy of the preformed and in-situ generated ruthenium complexes as precatalysts is demonstrated in asymmetric hydrogenations of allylic alcohols, enamides, and a β-keto ester.