Bernd Heiser

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

Abstract 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(η2-O2CCH3)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.