Development of ProPhenol Ligands for the Diastereo- and Enantioselective Synthesis of β‑Hydroxy-α-amino Esters

Abstract

A zinc–ProPhenol-catalyzed direct asymmetric aldol reaction between glycine Schiff bases and aldehydes is reported. The design and synthesis of new ProPhenol ligands bearing 2,5-<i>trans</i>-disubstituted pyrrolidines was essential for the success of this process. The transformation operates at room temperature and affords <i>syn</i> β-hydroxy-α-amino esters in high yields with good to excellent levels of diastereo- and enantioselectivity