Combining Wittig Olefination with Photoassisted Domino Reaction To Distinguish 5-Formylcytosine from 5-Formyluracil

In view of the important epigenetic functions of 5-formylcytosine (5fC), the development of quantitative detection methods for 5fC is a long-standing issue. In this regard, how to distinguish 5fC from 5-formyluracil to achieve higher accuracy is particularly difficult because the latter one is more reactive. Herein, we reported a phosphorus ylide, YC-CN , and introduced a triple domino reaction to fluorescently switch on 5fC with excellent selectivity, which also enable us to quantify 5fC mutations induced by γ-irradiation. This Wittig-initiated covalent labeling strategy provide a novel strategy for qualitative and quantitative detection of 5fC.