Aqueous tert-Butyl Hydroperoxide Mediated Regioselective Ring-Opening Reactions of Spiro-aziridine-epoxy Oxindoles: Synthesis of 3-Peroxy-3-substituted Oxindoles and Their Acid-Mediated Rearrangement.

A highly efficient regioselective C3-peroxylation of spiro-aziridine and spiro-epoxy oxindoles has been developed with commercially available 70% aqueous tert-butyl hydroperoxide under solvent-free and metal/catalyst-free conditions. The protocol provides an easy access of 3-peroxyoxindoles, which undergo acid-mediated rearrangement to afford unprecedented 2-hydroxy-2-substituted-2H-benzo[b][1,4]oxazin-3(4H)-ones. The protocol is also equally effective for the ring opening of simple phenyl aziridine with excellent regio-selectivity.