Synthesis of 2‑Phosphonylated\nC3 Spirocyclic\nIndolines via a Dearomatization–Spirocyclization–Nucleophilic\nAddition Tandem Approach of Indolyl-ynones with Phosphine Oxides

Due to its unique three-dimensional (3D) configuration\nand great\napplication potential in medicinal chemistry and synthetic community,\nchemists have been pursuing concise and efficient methods to synthesize\nC3 spirocyclic indoline derivatives. In this work, a dearomatization–spirocyclization–nucleophilic\naddition tandem approach was developed to realize the synthesis of\n2-phosphonylated C3 spirocyclic indolines with indolyl-ynones and\nphosphine oxides as reactants; mild conditions, broad substrate scope,\nand good yields are characteristics of this transformation.