Iodine-Catalyzed Oxidative [3+2] Annulation/Dehydrogenation Cascade: Synthesis of Unexpected Mesoionic [1,2,4]Triazolo[5,1- <i>a</i> ]isoquinoliniums

)-amines and isocyanates. The operationally simple, one-pot process proceeds under mild conditions through a cascade sequence of hydroamination, intramolecular cross-dehydrogenative coupling (CDC), and oxidative dehydrogenation. It features broad substrate tolerance and high atom and step economy. Furthermore, preliminary mechanistic studies indicate that the transformation likely proceeds via a hypoiodite-mediated pathway.