General approach for the synthesis of sarpagine/macroline indole alkaloids. Enantiospecific total synthesis of the indole alkaloid trinervine

[GRAPHICS] The total synthesis of the indole alkaloid trinervine 1 was accomplished in enantiospecific fashion in an overall yield of 20% (from the tetracyclic k etone 8) in 10 reaction vessels (12.5% from tryptophan methyl ester). The s ynthesis of the N-a-H substituted macroline equivalent 2 was also completed in high yield via the same intermediate 13. The unique protection/hydrobor atioin process developed here should provide a method to functionalize the C(19)-C(20) double bond in similar systems.