Planar-chiral ferrocenes in asymmetric catalysis:: The impact of stereochemically inhomogeneous ligands

[GRAPHICS] The catalytic properties of stereochemically inhomogeneous mixtures of chiral ferrocenes in dimethylzinc additions to benzaldehyde have been investigated. With planar chiral ferrocene (R-P) - a linear correlation between the enantiomeric excess of the ferrocene and that of the product was found. In contrast, a significant departure from linearity was revealed when mixtures of diastereomeric ferrocenes (S,R-p)-1 and (S,S-p)-3 were employed. Thus, even in the reaction with a catalyst obtained from a 1:1 ratio of diastereomers 1 and 3, formation of a product with an enantioselectivity of 95% ee was achieved.