Manganese-Catalyzed Ortho-C-H Alkenylation of Aromatic Ketones.

Ortho-C-H alkenylation of aromatic ketones is a key transformation for bioactive molecules and functional materials, but all existing methods rely on scarce noble metals, hindering industrial applications. Herein, we report the first manganese-catalyzed ortho-C-H alkenylation of aromatic ketones with commercial acrylates. Using MnBr-(CO)5 as the precatalyst, the reaction proceeds under mild aqueous conditions with broad substrate scope, scalable to 10 mmol, and allows tunable mono/bis-alkenylation via acrylate stoichiometry. Mechanistic studies support an electrophilic C-H metalation pathway, and the products can be readily derivatized to isoquinoline frameworks. This work provides a sustainable alternative and enables manganese catalysis with weakly coordinating directing groups.