Efficient Synthesis of (±)‐Horsfiline through the MgI2‐Catalyzed Ring‐Expansion Reaction of a Spiro[cyclopropane‐1,3′‐indol]‐2′‐one

We report a short synthetic route to (±)‐horsfiline that provides the racemate in five steps from commercially available, substituted isatin in 41% overall yield. Efficient entry into the spirooxindole‐pyrrolidine] ring system is possible through the application of the cyclopropane opening/ring expansion chemistry we have described with MgI₂ as a bifunctional catalyst.