Large scale preparation of versatile chiral auxiliaries derived from (S)‐proline¹

Abstract

Abstract The synthesis of a variety of enantiomerically pure chiral auxiliaries based on (S)‐proline and bearing sterically demanding side chains at the pyrrolidine moiety, such as the secondary amines (S)‐3,5 and 7 and the hydrazines (S)‐6, is described on a molar scale. As key step, the Grignard or RLi addition to the N‐benzylated proline ester (S)‐1 is used.