Méthyl N-[(2R,5S)-1-N-Benzyl-5-méthoxycarbonylprolyl]-(S)-phénylalaninate

In order to prepare new chiral auxiliaries useful in developing a new method of synthesis of optically pure amines or -amino acids, an unsymmetric derivative of pyrrolidine has been obtained, methyl 2-[(2R, 5S)-(1-benzyl-5-methoxypyrrolidin-2yl)carbonyl(S)-amino]-3-phenylpropanoate, C₂₄H₂₈N₂O₅. This has been crystallized and subjected to X-ray analysis in order to ascertain the absolute configuration of the two asymmetric C atoms of the ring. The five-membered ring is half-chair shaped. An intramolecular hydrogen bond links the amino N atom of the phenylalanine group to the carbonyl of the 5-methoxycarbonyl group.