L ‐ Tyrosinhydrazid als optisch aktive Base zur Spaltung von DL ‐Prolin, DL ‐Alanin und DL ‐Isoleucin in die optischen Antipoden

A new procedure for the resolution of DL ‐proline, DL ‐alanine and DL ‐isoleucine into the optical antipodes is outlined. It is based on the separation of diastereoisomeric salts of D‐ or L ‐tyrosine hydrazide with Z‐ DL ‐proline, Z‐ DL ‐alanine and Z‐ DL ‐isoleucine, by means of fractional crystallization in suitable solvents such as lower aliphatic alcohols and water. It is shown that the new method gives excellent yields even with half the molar amount of the optically active resolving agent.