Versatile solid-phase synthesis of peptide-derived 2-oxazolines. Application in the synthesis of ligands for asymmetric catalysis

A mild and high-yielding procedure for the solid-phase synthesis of 2-oxazolines from amino acids is described. The two-step protocol is based on the iodination of serine containing peptides, followed by in situ nucleophilic attack of the carbonyl oxygen from the next amino acid. Phosphinylation of the terminal amino group cleanly furnishes a resin-bound phosphine-oxazoline ligand, which upon palladium complexation was applied as catalyst in asymmetric allylic substitution. [reaction: see text]