Beitrag zur asymmetrischen Synthese bicyclischer Verbindungen unter Katalyse mit optisch aktiven Aminosäuren. Synthese von (<i>S</i>)‐2‐Pyrrolidin‐propionsäure und (<i>R</i>)‐4‐Amino‐5‐phenylvaleriansäure

Abstract

Contribution to the asymmetric synthesis of bicyclic compounds catalysed by optically active amino acids. Synthesis of ( S )‐2‐pyrrolidinepropionic acid and ( R )‐4‐amino‐5‐phenylvaleric acid The evaluation of literature data concerning the asymmetric cyclization of the prochiral monocyclic triketones 1 to the enediones 3 shows that catalysis with optically active α‐amino acids of the ( S )‐series leads to an excess of products having the same absolute configuration as natural steroids at C (13), while those of the ( R )‐series favour the formation of the enantiomers ( Scheme 1 ). With 1a as substrate an inverse asymmetric course was observed using the optically active β‐amino acids 5 , 8 and 10 as catalysts ( Table 1 ). Furthermore, the synthesis of the optically active γ‐amino acids 6 and 11 using the Arndt ‐ Eistert process is described. The influence of these latter compounds on the asymmetric transformation of 1a into 3a has been investigated.