γ-Carbonyl Quinones: Radical Strategy for the Synthesis of Evelynin and Its Analogues by C–H Activation of Quinones Using Cyclopropanols

Cyclopropanols, on oxidative ring opening with AgNO3-K2S2O8 in DCM-H2O at room temperature and under open flask conditions, produced β-keto radicals which were successfully added to quinones to furnish γ-carbonyl quinones. This mild method has been applied to the synthesis of cytotoxic natural products, 4,6-dimethoxy-2,5-quinodihydrochalcone and evelynin.