Asymmetric Divergent Total Syntheses of (+)-Decursivine and (+)- Serotobenine via Intramolecular Fischer Indole Synthesis.

A new asymmetric synthetic route to (+)-decursivine and (+)-serotobenine is formulated. The key developments are the de novo construction of the crucial eight-membered 3,4-fused tricyclic indole ring engaged by the intramolecular Fischer indole synthesis and the stereocontrolled assembly of the dihydrobenzofuran subunit mediated by the asymmetric intramolecular Rh-carbenoid C-H insertion. BF 3 -mediated selective C15 epimerization followed by removal of the amine masking groups completed the target natural compounds' asymmetric and divergent total syntheses.