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

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.