Synthesis of Quaternary 3,3-Disubstituted 2-Oxindoles from 2-Substituted Indole Using Selectfluor

A facile method to construct quaternary 3,3-disubstituted 2-oxindole from 2-substituted indole without a catalyst in mild conditions is developed. A mechanistic study suggests that an iminium-intermediate-triggered 1,2-rearrangement is involved, and a trace amount of water is required for subsequent oxidation.