Enantiopure N-ferrocenylmethylaziridin-2-ylmethanols from L-serine: synthesis, crystal structure and applications

A convenient and practical 'one-pot procedure' for the synthesis of methyl N-ferrocenylmethylaziridine-2-carboxylates 2 from the N-ferrocenylmethyl-L-serine methyl ester in the presence of p-toluenesulfonyl chloride and triethylamine is described. N-Ferrocenylmethylaziridin-2-ylmethanol 1 is a new type of beta-amino alcohol ligand and is prepared from the corresponding methyl N-ferrocenylmethylaziridine-2-carboxylates 2 through a Grignard reaction. The crystal structures of compounds 1 and 2 reveal that the N-ferrocenylmethyl group is positioned anti to the hydroxymethyl group or ester group, respectively. X-ray analysis indicates that in aziridine alcohols 1, an intramolecular hydrogen bond is present in the crystalline state. The chiral ligands 1 were used as catalyst to promote the asymmetric addition of diethylzinc to benzaldehyde affording 1-phenylpropanol in up to 92.7% enantiomeric excess with excellent yields. (C) 2004 Elsevier Ltd. All rights reserved.