Kinetic and thermodynamic control in the stereoselective formation of trans- and cis-2-ferrocenyl-3-pivaloyl-4-alkyl-1,3-oxazolidin-5-ones

Abstract

A range of ferrocenylimines derived from ferrocenecarboxaldehyde and the α-amino acids (S)-alanine, (S)-2-aminobutyric acid, (S)-norvaline, (R)-2-phenylglycine, (S)-phenylalanine, O-benzyl (S)-serine, and (S)-tryptophan can be cyclised stereoselectively to afford either the corresponding cis- or trans-2-ferrocenyl-3-pivaloyl-4-alkyl-1,3-oxazolidin-5-ones. The cyclisation reaction shows marked temperature dependence, giving rise preferentially to the trans-oxazolidinone under kinetic control (−78 °C) and the thermodynamic cis-oxazolidinone at −15 °C to rt.