Reactivity of aminopyrroles: Protonation

Abstract The behaviour of 2‐ and 3‐aminopyrroles towards protonation is similar. In dimethyl sulphoxide/trifluoroacetic acid they are protonated at the exocyclic nitrogen, whereas in pure trifluoroacetic acid, protonation at the 5‐ and/or 3‐position of the ring takes place.