Fluorogenic Probe Using a Mislow–Evans Rearrangement for Real‐Time Imaging of Hydrogen Peroxide

Hydrogen peroxide (H2 O2 ) mediates the biology of wound healing, apoptosis, inflammation, etc. H2 O2 has been fluorometrically imaged with protein- or small-molecule-based probes. However, only protein-based probes have afforded temporal insights within seconds. Small-molecule-based electrophilic probes for H2 O2 require many minutes for a sufficient response in biological systems. Here, we report a fluorogenic probe that selectively undergoes a [2,3]-sigmatropic rearrangement (seleno-Mislow-Evans rearrangement) with H2 O2 , followed by acetal hydrolysis, to produce a green fluorescent molecule in seconds. Unlike other electrophilic probes, the current probe acts as a nucleophile. The fast kinetics enabled real-time imaging of H2 O2 produced in endothelial cells in 8 seconds (much earlier than previously shown) and H2 O2 in a zebrafish wound healing model. This work may provide a platform for endogenous H2 O2 detection in real time with chemical probes.