Design and synthesis of enantiopure 1-[1(S)-(2-pyridyl)alkyl]-2(R)-isopropylaziridines, new ligands for asymmetric catalysis

Enantiopure 1-(2-pyridyl)alkyl aziridines were designed as bidentate ligand s for asymmetric catalysis. Their synthesis involved the addition of organo metallic reagents to the imine prepared from 2-pyridinealdehyde and an enan tiopure beta-aminoalcohol, followed by cyclisation of the beta-aminoalcohol moiety to the aziridine ring. Two such ligands (N-N)* were prepared from ( S)-valinol and converted to the complexes (eta(3)-allyl)(N-N)*Pd(+)SbF6(-), one of which was characterised by X-ray crystallography. Modest enantiosel ectivities were achieved in a representative Pd-catalysed allylic substitut ion reaction. (C) 2000 Published by Elsevier Science Ltd. All rights reserv ed.