Synthesis of Indoline-2,3-diones by Radical Coupling of Indolin-2-ones with tert-Butyl Hydroperoxide

A novel strategy has been developed for the synthesis of indoline-2,3-diones through a metal-free radical-coupling reaction. Alkyl radicals derived from indolin-2-ones through a radical-transfer reaction combine with the tert-butylhydroperoxy radical readily generated from commercially available tert-butyl hydroperoxide to afford 3-(tert-­butylperoxy)indolin-2-one intermediates that can be further transformed into indoline-2,3-diones under air. This strategy provides a ­simple and efficient route to the construction of a C=O bond without the use of any metal catalyst or base.