Manganese-Catalyzed Aromatic C-H Allylation of Ketones.

Manganese-catalyzed aromatic C-H allylation of ketones is reported. The reaction proceeded in a monoselective allylation manner to provide various ortho C-H allylated ketones in high yields. With challenging allylic electrophiles bearing substituents at the α-, β-, or γ-position, excellent SN2' regioselectivity was achieved under mild conditions (rt to 35 °C). Mechanistic studies revealed a possible turnover-limiting C-H bond cleavage step affording a five-membered manganacycle followed by reaction with allylic electrophiles to give the C-H allylation product.