Photo-accelerated “Click” Reaction between Diarylsydnone and Ring-strained Alkyne for Bioorthogonal Ligation

We constructed a library of diarylsydnone (DASyd) candidates in search of a photoclickable reaction toward alkynes, enabling an ultra-accelerated reactivity, while suppressing the background cycloaddition in the dark. The in vitro and in vivo protein labelling experiments revealed that the photo-accelerated DASyd–alkyne cycloaddition exhibits robust selectivity.