Metal-free formal carbon-halogen bond insertion: facile syntheses of 3-halo 3,3'-disubstituted oxindoles and spirooxindole-γ-butyrolactones.

A novel P(NMe2 )3 -mediated formal carbon-halogen bond insertion of isatins into allylic and benzylic bromides/chlorides has been realized, leading to a facile synthesis of 3-halo 3,3'-disubstituted oxindoles. This reaction relies on the unique dual nucleophilic-electrophilic reactivity pattern of the Kukhtin-Ramirez adduct via a cascade SN 2-SN 2 process. It also represents a rare metal-free approach for carbon-halogen bond insertion. Upon treatment with trifluoroacetic acid, spirooxindole-γ-butyrolactones have been efficiently prepared from the corresponding insertion products.