초록
<P><B>Abstract</B></P><P>The (+)‐ as well as the (−)‐enantiomer of the pyrrolizidine alkaloid xenovenine were prepared within five steps with 17 and 30% overall yields, respectively, in optically pure form, >99% <I>ee</I> as well as >99% <I>de</I>. In the asymmetric key step a transaminase performed a regio‐ and stereoselective monoamination of a triketone. By employing two enantiocomplementary transaminases from <I>Arthrobacter</I> sp. both enantiomers were accessible. The triketone was readily prepared <I>via</I> two steps starting from commercially available, achiral 2‐(<I>n</I>‐heptyl)furan. In the final catalytic hydrogenation step, the newly introduced chiral centre directed hydrogen addition to form preferentially the desired (5<I>Z</I>,8<I>E</I>)‐diastereomer. The regio‐ and stereoselective amination of a single ketone moiety out of three allowed the performance of the shortest and highest yielding total synthesis of the bicyclic showcase pyrrolizidine alkaloid without the need for protecting strategies.</P>