Planar chiral mimetics. A new approach to ligand design for asymmetric catalysis

(S)-Serine methyl ester is readily transformed into 4-(hydroxymethyl)oxazol ine ligands containing either a 2-(eta (5)-cyclopentadienyl)(eta (4)-tetrap henylcyclobutadiene)cobalt or a 2-(1,2,3,4,5-pentaphenyl)-ferrocene substit uent. The influence of the bulky metallocenes result in these ligands mimic king planar chirality, as demonstrated by their catalysis of the addition o f diethylzinc to benzaldehyde resulting in (R)-1-phenylpropanol (75% e.e.). (C) 2000 Published by Elsevier Science Ltd.