Diketopiperazine-derived hydroperoxide for chemoselective oxidations of sulfides and enantioselective Weitz–Scheffer epoxidations

l-Proline-derived hydroperoxide (−)-2, which was obtained from the corresponding diketopiperazine by irradiation under oxygen atmosphere, was applied to the oxidation of a variety of sulfides and asymmetric Weitz–Scheffer epoxidations of cyclic and acyclic enones. The sulfoxidation, however, gave only racemic products. In contrast, depending on the base catalyst, enantioselectivities up to 37% were achieved in the epoxidation of chalcone with (−)-2.