An Ag(I)-catalyzed dearomatizing spirocyclization/allylation cascade: synthesis of allylated spiroindolines from indole-tethered ynones.

Herein, we report an Ag(I)-catalyzed strategy for the synthesis of C2 allylated spiroindolines from indole-tethered ynones and allyltri-methylsilanes. The developed protocol involves a 5-/6-endo-dig dearomatizing spirocyclization of indole-tethered ynones, followed by nucleophilic allylation of the resulting spiroindolenine intermediate using diverse allyltrimethylsilanes. This transformation enables the formation of two new C-C bonds and two contiguous stereocenters with excellent diastereoselectivity.