Synthesis of 2-Phosphonylated C3 Spirocyclic Indolines via a Dearomatization–Spirocyclization–Nucleophilic Addition Tandem Approach of Indolyl-ynones with Phosphine Oxides

Due to its unique three-dimensional (3D) configuration and great application potential in medicinal chemistry and synthetic community, chemists have been pursuing concise and efficient methods to synthesize C3 spirocyclic indoline derivatives. In this work, a dearomatization–spirocyclization–nucleophilic addition tandem approach was developed to realize the synthesis of 2-phosphonylated C3 spirocyclic indolines with indolyl-ynones and phosphine oxides as reactants; mild conditions, broad substrate scope, and good yields are characteristics of this transformation.