Simple Aziridino Alcohols as Chiral Ligands. Enantioselective Additions of Diethylzinc to N-Diphenylphosphinoylimines.

Simple chiral aziridino alcohols 2-5, easily available from L-serine, L-threonine or L-allo-threonine, have been used as ligands to promote the addition of Et(2)Zn to the diphenylphosphinoylimine 1 (Ar=Ph). Enantioselectivities of up to 94% could be obtained by proper choice of the substituents on the ligand. Up to 90% of the ligand could be recovered during the work-up. The use of ligand 3a as catalyst for the same reaction has also been studied.