Synthesis of pyrido[1,2-]indol-6(7)-ones a visible light-photocatalyzed formal (4 + 2) cycloaddition of indole-derived bromides and alkenes or alkynes

We successfully developed an unprecedented synthesis route to pyrido[1,2- a ]indol-6(7 H )-ones through a visible light-photocatalyzed formal (4 + 2) cycloaddition of indole-derived bromides and alkenes or alkynes in a microchannel reactor. This novel protocol features extremely mild conditions, a broad substrate scope and high reaction efficiency. In addition, a reasonable reaction mechanism based on controlled experiments was proposed. We successfully developed an unprecedented synthesis route to pyrido[1,2- a ]indol-6(7 H )-ones through a visible light-photocatalyzed formal (4 + 2) cycloaddition of indole-derived bromides and alkenes or alkynes in a microchannel reactor.