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.