Radical Rearrangement of Terminal Epoxides to Methyl Ketones via Cobalt Photocatalysis.

The acid-catalyzed Meinwald rearrangement of epoxides is a powerful and economical method for generating carbonyl compounds, but regioselectivity is dominated by carbocation stability. Herein, we report a redox-neutral and highly selective cobaloxime-photocatalyzed protocol for the isomerization of terminal epoxides to methyl ketones under visible-light irradiation. This system provides complementary products to the Meinwald rearrangement under mildly basic conditions and exhibits broad functional group tolerance. Additionally, preliminary investigations suggest it proceeds through a radical mechanism.