N

Under rhodium catalysis N-sulfonio(sulfilimines) act as sulfonitrene precursors. Reaction of such species with indenes presumably delivers N-sulfonio aziridines, which evolve to isoquinolines via electrocyclic ring expansion. Contrarily, 1-arycyclobutenes are transformed into 1-cyano-1-arylcyclopropanes via ring contraction.