The synthesis of symmetrical 3,3-Disubstituted oxindoles by phosphine-catalyzed γ/γ-addition of oxindoles with allenoates

A phosphine-catalyzed γ/γ-addition of oxindoles with allenoates has been developed that enables the efficient synthesis of highly functionalized symmetrical 3,3-disubstituted oxindoles. This protocol features mild reaction conditions and wide functional group tolerance and affording corresponding addition products in good to excellent yields. Besides, we have also investigated the biological utility of the typical 3,3-disubstituted oxindoles against nine phytopathogenic fungi, and 3a and 3d exhibited promising antifungal activities.