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

Abstract

We successfully developed an unprecedented synthesis route to pyrido[1,2-a]indol-6(7H)-ones through a visible light-photocatalyzed formal (4 + 2) cycloaddition of indole-derived bromides and alkenes or alkynes in a microchannel reactor.

Synthesis of imidazo[1,2-a]pyridinones via a visible light-photocatalyzed functionalization of alkynes/nitrile insertion/cyclization tandem sequence using micro-flow technology

“…On the basis of these studies, control experiments, and previous reports, 30,[35][36][37][38][39] a plausible mechanism was proposed (Scheme 6). First, the organic photocatalyst PC-B was exposed to visible light to form an excited state PC-B*.…”

Recent advances in radical-mediated intermolecular (4 + 2) cycloaddition

“…In this context, Guo, Fang and their co-workers collaborated to design the following strategy to achieve an unprecedented synthesis route to pyrido[1,2- a ]indol-6(7 H )-ones, which was developed via visible light photocatalytic (4 + 2) cycloaddition of indole-derived bromides and olefins or alkynes in a microchannel reactor (Scheme 28). 41 To investigate the application value of this reaction, they performed a continuous flow scale-up experiment of this reaction and obtained an excellent yield of 88 (Scheme 28). Then, they proposed a possible reaction mechanism based on the mechanistic investigation experiments and related literature reports.…”