A transition metal-free and oxidation-free dearomatization of phenols through conjugate addition to in situ generated indol-2-one from 3-bromooxindole is detailed in this report. This methodology offers an effective approach for the synthesis of a range of 3-substituted oxindoles containing contiguous quaternary carbon centers (CQCCs) with yields of up to 99%. The reaction is characterized by mild conditions, exceptional efficiency, environmental compatibility, favorable functional group tolerance, and scalability to large-scale production.