Manganese-Catalyzed Asymmetric Oxidation of Methylene C-H of Spirocyclic Oxindoles and Dihydroquinolinones with Hydrogen Peroxide.

A highly efficient strategy for the enantioselective oxidation of methylene C-H of spirocyclic oxindoles and dihydroquinolinones has been established, in which an earth-abundant manganese catalyst and hydrogen peroxide are used. Noteworthy, the manganese catalyst can be applied to the asymmetric hydroxylation of spirocyclic 2,3-dihydroquinolin-4-ones with 94-99% ee.