CrCl 2 mediated allylation of N-protected α-amino aldehydes. A versatile synthesis of polypeptides containing an hydroxyethylene isostere

Abstract

Differently substituted allylic bromides react with N-protected amino aldehydes to give intermediate products for the synthesis of hydroxyethylene dipeptide isosteres. The low stereoselectivity of this reaction can be improved using aldehydes protected with hindered groups. This reaction can be efficiently applied to oligopetide aldehydes. We describe a protocol, for the preparation of peptides containing an hydroxyethylene isostere, which allows a rapid variations of the aminoacid sequence