Anwendung der 2-Azaallylanionen-Cycloaddition in der enantioselektiven Totalsynthese von (+)-Coccinin

Abstract

Ein hochfunktionalisiertes Perhydroindol entsteht bei der intramolekularen [π4s+π2s]‐Cycloaddition eines 2‐Azaallylanions mit einem Vinylsulfid [Gl. (a), Bn=Benzyl]. Dies ist der Schlüsselschritt bei der Totalsynthese von (+)‐Coccinin, dem Enantiomer des Amaryllidaceae‐Alkaloids (−)‐Coccinin.

Bioinspired Total Synthesis of Montanine‐Type Amaryllidaceae Alkaloids

“…In various approaches to the assembly of the 5,11‐methanomorphanthridine skeleton, the five types of advanced synthons I – V (Scheme ) have been strategically involved,6–10 and the closure of ring C, D, C/D, or E has constituted the final step in the construction of the polycyclic system. Significantly, the synthetic elaboration of these synthons I – V has involved the elegant development and application of many novel methodologies (e.g., an aza‐Cope rearrangement/Mannich cyclization,5a, 6a an allenylsilane imino ene reaction,9b,c a [3+2] cycloaddition,6b,g, 10 and a chemoenzymatic approach6i,k,l). Despite the substantial progress made in the racemic5, 6c–e,o, 7, 8, 9a, 10 and asymmetric6a,b,f–n, 9b,c synthesis of the montanine‐type alkaloids, a general strategy for the effective bioinspired total synthesis of these architecturally unique molecules has not previously been explored.…”