o-Nitrobenzyl oxime ethers enable photo-induced cyclization reac-tion to provide phenanthridines under aqueous conditions

In this paper, we describe a novel N–O photolysis of o-nitrobenzyl oxime ethers that enables the synthesis of phenanthridines via intramolecular cyclization reactions. Without the use of additional photocatalysts or photosensitizers, the process proceeds with an efficiency of up to 96% when exposed to near-visible light (405 nm) under aqueous circumstances. Through the photoinduced production of a fluorescent phenanthridine derivative in HeLa cells, biocompatibility of the reaction was demonstrated. This photoinduced cyclization reaction could be used as a different photochemical instrument to control biological processes by inducing the production of bioactive molecules.