New Cleavage of the Azirine Ring by Single Electron Transfer: The Synthesis of 2H-Imidazoles, Pyridazines and Pyrrolines

Here we report the first example of the dimerisation of azirines to 2H-imidazoles or 3,5-disubstituted pyridazines from a reaction promoted by FeCl2. An azirine complex with a radical structure is proposed as an intermediate. Cyclopropyl ketones and pyrrolines are isolated when the reaction is carried out in the presence of styrenes.