Metal-free Oxidative Spirocyclization of Pyrrole-2-carboxamides

A catalyst-free oxidative spirocyclization reaction has been successfully developed for the synthesis of 3,3'-pyrrolidinyl spirooxindole derivatives from readily accessible pyrrole-2-carboxamides. The resulting 3,3'-pyrrolidinyl spirooxindoles can be selectively transformed into hydrogenated spiroindoles via a reduction process. The dual functionality of Selectfluor is noteworthy, as it may serve both as an oxidizing and fluorinating agent and as a precursor for an alkaline promoter. The present spirocyclization method offers advantages such as a simple operation and mild reaction conditions.