Thioether-based anchimeric assistance for asymmetric coordination chemistry with ruthenium(II) and osmium(II).

(R)-4-(alkylthiomethyl)-5,5-dimethyl-2-(2'-hydroxyphenyl)-2-oxazolines are demonstrated to be highly suitable chiral auxiliaries for the two-step conversion of the half-sandwich complex [Ru(η(6)-C6H6)(bpy)Cl]Cl, bpy = 2,2'-bipyridine, into Δ-configured ruthenium polypyridyl complexes. The tailored thioether substituent at the oxazoline ring is essential for this conversion and not only promotes the removal of the benzene moiety but also controls the absolute metal-centered configuration. Applied to osmium, this strategy resulted in the first highly asymmetric synthesis of Δ-[Os(bpy)3](PF6)2.