Herein, we report a novel bioorthogonal reaction that
hinges on
a bridgehead alkene (BHA)-enabled inverse-electron-demand Diels–Alder
(IEDDA) cycloaddition. Readily accessible from natural product β-caryophyllene,
the strained BHA displays high reactivity toward the IEDDA reaction
while maintaining excellent biocompatibility. The developed IEDDA
reaction has been applied to in vitro protein labeling
and pretargeted live cell imaging