We report herein ap ractical method to generate CF 3 S À and R F S À anions in situ from shelf-stabler eagents, which werei nitially designed for electrophilic reactions. With an "iodidea ctivation"s tep, these in situ released anionsc an directly participate in metal-free nucleophilic substitution reactions with the loss of variousl eaving groups. Our method is compatible with variousf unctional groups and provides good yields. With this strategy, the first directn ucleophilic perfluoroalkylthiolation reactions have been described.

Protein labeling using fluorogenic probes enables the facile visualization of proteins of interest. Herein, we report new fluorogenic probes consisting of a rationally designed coumarin ligand for the live‐cell fluorogenic labeling of the photoactive yellow protein (PYP)‐tag. On the basis of the photochemical mechanisms of coumarin and the probe–tag interactions, we introduced a hydroxy group into an environment‐sensitive coumarin ligand to modulate its spectroscopic properties and increase the labeling reaction rate. The resulting probe had a higher labeling reaction rate constant and a greater fluorescence OFF–ON ratio than any previously developed PYP‐tag labeling probe. The probe enabled the fluorogenic labeling of intracellular proteins within minutes. Furthermore, we used our probe to investigate the localization of sirtuin 3 (SIRT3), a mitochondrial deacetylase. Although the nuclear localization of SIRT3 has been controversial, this transient nuclear localization was clearly captured by the rapid, high‐contrast imaging enabled by our probe.

No abstract