Pd(II)-Catalyzed Aminofluorination of Alkenes in Total Synthesis 6‑(R)‑Fluoro­swainsonine and 5‑(R)‑Fluoro­febrifugine

The total syntheses of two fluorinated alkaloids, 6-(R)-fluoro­swainsonine and 5-(R)-fluoro­febrifugine, are described. Both encompass (4aS,7R,8aR)-7-fluoro-5-tosylhexa­hydro-4H-[1,3]­dioxino­[5,4-b]­pyridine as a key synthon which is obtained through a further optimized palladium-catalyzed aminofluorination of alkenes with high diastereoselectivity. 6-(R)-Fluoroswainsonine is synthesized from the key synthon in 14 steps, and 5-(R)-fluorofebrifugine requires a sequential 15-step transformation.