[3 + 2] Cycloadditions with Azirines under the Conditions of Photoinduced Electron Transfer: A New Method for the Synthesis of Imidazoles and Heterophanes

With the opening of azirine rings under the conditions of photoinduced electron transfer a new synthon for the synthesis of heterocycles is available. The formed 2‐azaallenyl radical cation readily reacts with imines to form N 1‐substituted imidazoles in reasonable yields. The synthesis of pyrrolophanes and imidazolophanes from bicyclic azirines is possible as well. With oligocyclic azirines complex heteroaromatic systems and even a porphyrin system can be built up.