A palladium-catalyzed spirocyclization forming spirooxindoles and spirodihydrobenzofurans has been achieved. Mechanistic studies suggest that the transformation proceeds through sequential carbopalladation, C-H activation, and benzyne insertion. Both classes of spirocycles have been synthesized in good to excellent yields, and the procedure is readily scalable.

Maleimide-based Diels–Alder strategies for bioconjugation are compared in terms of dienes accessibility and stability, reactions rates, as well as products isolation and stability.