Abstract When activated in the CF 3 SO 3 H/SbF 5 acid system maleimide (1) and phthalimide (2) undergo selective ionic hydrogenation with cyclohexane to give 1, 5- dihydropyrrol-2-one (3) and phthalimidine (11), respectively. When treated with aluminum halides, N-phenylmaleimide (4) reacts with cyclohexane to give N-phenylsuccinimide (5), whereas 2 still gives 11. Imide 1 also condenses with benzene in trifluoromethanesulfonic ...