The pentacyclic Aspidosperma alkaloid dZ-16-methoxytabersonine (1) has been synthesized by an efficient convergent sequence. The key step in the synthesis is the "ring-enlarging pyrrolidine annulation" reaction of 7-styrylhydropyridin-7-ols 17 and 18 to give 9a-arylhydrolilolidine 19 and 16-methoxy-l,2,6,7-tetradehydroaspidospermidine (20), respectively.
Aus dem Brom‐pyrrolin (I) entsteht ein Ether (II), der nach Reduktion zu einem cis/trans‐Gemisch über den Ester (IIIa) und das Dipeptid (IIIb) zu Zizyphin A (IVb) cyclisiert und kondensiert werden kann.
Ausgehend vom 6‐Brom‐tryptophan‐Derivat (II) und dem aus (Ia) zugänglichen Amin (Ie) wird auf dem im Formelschema skizzierten Weg das Tetraacetylclionamid (IVb) hergestellt.
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