C(sp3)–H Peroxidation of 3-Substituted Indolin-2-ones under Metal-Free Conditions

Abstract

A C(sp3)–H peroxidation of 3-substituted indolin-2-ones through radical coupling reaction has been developed under metal-free conditions. Using tert-butyl hydroperoxide both as an oxidant and as a peroxidation reagent to couple with the C(sp3)–H bonds of 3-substituted indolin-2-ones can form a new C–O bond without using any additives. This simple strategy provides a green and efficient approach to 3-peroxyindolin-2-ones in moderate to excellent yields. The resulting 3-peroxyindolin-2-ones could be further transformed into 3-hydroxy­indolin-2-ones.

Peroxidation and Skeletal Rearrangement for the Synthesis of Dioxole‐2‐Carboxamide Derivatives under Continuous‐Flow Conditions

“…Other research groups have reported a few other rearrangements using different heterocyclic peroxides [14] . Although several peroxidation reactions have been achieved using metal [15] towards the skeletal rearrangement reaction, very limited metal‐free conditions [16a–c] for peroxidation of 3‐substituted indolin‐2‐ones, [16d] and 3,4‐dihydro‐1,4‐benzoxazin‐2‐ones 16e have been accounted recently. In addition, a transition metal catalyst [10] and stoichiometric reagents [11] have been used for the peroxidation of 2‐naphthols.…”