Metal‐free Cross‐Dehydrogenative Coupling for α‐Arylation of 3‐Aryloxindoles

The creation of quaternary carbon centers has been a formidable challenge in organic synthesis due to steric impediments, especially for the polyaryl substituted quaternary carbon centers. Up to now, a few of methods were reported for achieving the α‐arylation of 3‐aryloxindoles to construct 3,3‐diaryloxindoles. We now asserted the TfOH‐catalyzed cross‐dehydrogenative coupling reaction between the tertiary C(sp3)‐H and readily available arenes under air atmosphere in green reaction medium for rapid construction of 3,3‐diaryloxindoles. In addition, the mechanism of the metal‐free cross‐dehydrogenative coupling with air as oxidant was meticulously explored.