Visible light-induced selective aerobic oxidative transposition of vinyl halides using a tetrahalogenoferrate( iii ) complex catalyst

We report tetrahalogenoferrate( iii ) complexes as a new kind of iron photocatalyst. These complexes are easily prepared from FeCl 3 with lithium bromide or ammonium bromides, and have a good and tunable photo-sensitivity in the visible light region. Their distinct catalytic mode with FeCl 3 enables a highly chemoselective photooxygenation of benzylic sp 3 C–H, providing a series of carbonyls in moderate to excellent yields. The method has also been employed in the challenging aerobic oxidative transposition of vinyl halides, thus facilitating a mild and highly efficient approach to access significant α-halo ketones with a broad substrate scope. The disclosure of tetrahalogenoferrate( iii ) complex photocatalysts should provide inspiration for their expansion to new aerobic oxidative reactions and even anaerobic variations.