Chiral-Auxiliary-Mediated Asymmetric Synthesis of Tris-Heteroleptic Ruthenium Polypyridyl Complexes

A strategy for the asymmetric synthesis of chiral-at-metal [Ru(pp)(pp')(pp'')](2+) complexes, where pp, pp', and pp'' are achiral 2,2'-bipyridines, is introduced. The method employs isopropyl-2-(2'-hydroxyphenyl)oxazolines as chiral auxiliaries, which serve in their deprotonated forms as strong bidentate ligands that provide excellent asymmetric induction in the course of the coordination chemistry and, importantly, can afterward become substituted with complete retention of configuration in the presence of acid.