A Concise and Versatile Synthesis of Alkaloids from Kopsia tenuis : Total Synthesis of (±)‐Lundurine A and B

A total synthesis of (±)‐lundurines A and B is described. These natural products have a unique hexacyclic skeleton which includes a cyclopropane‐fused indoline. A stereospecific construction of the pentasubstituted cyclopropane core was achieved, by radical cyclization using SmI 2 , with perfect stereoselectivity. Cyclizations to give seven‐ and five‐membered heterocycles, under palladium and ruthenium catalysis, respectively, accomplished the total syntheses. The late‐stage construction of the F ring by ring‐closing metathesis enabled access to the title compounds from a spiroindoline intermediate which is a common structure of other kopsia alkaloids.