A number of 5-(alkylamino)-or 5-(arylamino)-2H-pyrrolium butyl isocyanide converts the protonated Ξ±-chlorocinnamaldimines 2j,k into the 5-(tert-butylamino)-pyrrole-2-salts 3 or 5 have been obtained by treating the 1-aza-1,3diene hydrochlorides 2 with isocyanides R 4 NC in refluxing carbonitriles 13. Structural assignments of all the cycloadducts have been made on the basis of their NMR-acetonitrile or chloroform for a few hours. Depending on the experimental conditions, deprotonation of these species can spectroscopic properties, particularly the effects observed in NOEDIFF experiments. Mechanisms are suggested to occur in the reaction medium to furnish the corresponding 2aminopyrroles 4 and 6. Insertion of isocyanide into a carbon-account for the ring-closure reactions and autoxidation of pyrroles 4 and 6 under atmospheric oxygen to give the 5-hydrogen bond of the pyrrolium salts can also lead to the generation of the (pyrrol-2-yl)methyleneiminium chlorides 7-imino-2-pyrrolinones 17 and 18. 9. Under similar conditions, treatment with an excess of tert-Substituted pyrroles are a class of heterocycles of con-roles or related compounds, [5,11,12] can be classified as C 2 Ο©C 2 methods. siderable interest owing to their wide distribution in nature and the remarkable diversity of their biological activities. They form part of the molecular structure of many alkaloids and natural macrocycles (hemes, bile pigments, chlorophylls, etc.) and are used in constructing attractive materials such as porphyrins, [1] expanded porphyrins and their heterologs, [2] porphyrazines, [3] and open-chain polypyrroles.