Divergent Construction of Spirocyclopentene-3,2'-indolines with Vicinal Stereocenters via Palladium-Catalyzed Aza-Wacker Cyclization.

Herein, we report an aerobic palladium-catalyzed aza-Wacker cyclization to produce spirocyclopentene-3,2'-indolines with vicinal stereocenters. Using 1,2-bis(diphenylphosphino)benzene (dppbz) and pyridine as ligands, we achieved a ligand-modulated diastereodivergent synthesis, producing cis- and trans-spirocyclopentene-3,2'-indolines with exceptional yields and diastereoselectivities. Density functional theory (DFT) calculations revealed that selective aza-Wacker cyclization proceeds through distinct trans- and cis-aminopalladation mechanisms.