Use of tailored boronic acids both as a radical donor and acceptor in a visible light-mediated di-functionalization of maleimides: rapid access to fused benzo[e]isoindole-1,3-diones

Abstract

A visible light-mediated di-functionalization of maleimide with boronic acid is unveiled for synthesizing a library of benzo[e]isoindole-1,3-diones via a radical addition cascade cyclization (RACC) strategy. This acid/base-free method involved a hypervalent iodine reagent and Ru-photocatalyst. The tailor-made boronic acids performed a dual role as a radical donor and a radical acceptor. The stoichiometry of the reagents and functional group tolerance of the reaction were remarkable, whereas the yields of the products were excellent without any scalability issues. Mechanistic studies suggested the presence of a radical pathway during the reaction.