2-amino-substituted 1-sulfinylferrocenes as chiral ligands in the addition of diethylzinc to aromatic aldehydes.

A simple and modulable access to a structural variety of enantiopure amino-substituted ferrocenyl sulfoxides and their use as chiral catalysts in the asymmetric addition of diethylzinc to aromatic aldehydes is described. Moderate to high enantioselectivities (up to 96% ee) were obtained in the case of the arylsulfonamide ligands (R Fc , Rs)-4h and (R Fc , R S )-4i. It has been demonstrated that the planar chirality of the ferrocene unit is the decisive chiral element involved in the reaction.