Total Synthesis of (–)‐Fasicularin and (–)‐Lepadiformine A Based on Zn‐Mediated Allylation of Chiral N‐tert‐Butanesulfinyl Ketimine

The stereoselective total synthesis of fasicularin (1) andlepadiformine A (2) is described, which features the utilization of a Zn‐mediated allylation of a chiral, aliphatic, N‐tert‐butanesulfinyl ketimine to construct the amino‐substituted quaternary carbon center in good yield and with excellent diastereoselectivity. The azaspirocyclic scaffold was installed sequentially by a Sharpless dihydroxylation and an internal epoxide‐opening reaction, and this scaffold was further converted into common intermediate 5. Removing the tosyl (Ts) protecting group of 5 and reductively aminating usingLuche's reagent completed the synthesis of (–)‐fasicularin (1), while reducing 5 using L‐selectride, deprotecting the Ts group, and finishing with an intramolecular amino alcohol cyclocondensation completed the total synthesis of (–)‐lepadiformine A (2).