A Stereocontrolled, Convergent Synthesis of Hydroxyethylene Dipeptide Isosteres

A simple, convergent, and stereoselective synthesis of hydroxyethylene dipeptide isosteres 1 and 2 from scalemic α-hydroxy esters has been developed. The method is short (six steps), efficient (≈15−25% overall), and highly diastereoselective (86−94% de) and enantioselective (>95% ee).