Study of the nucleophilic behaviour of N-phenylbenzamidine towards 1,2-diaza-1,3-dienes: domino reactions for imidazole scaffolds

Depending on the nature of the solvent, alcohol or DMF, N-phenylbenzamidine shows different nucleophilic behaviour towards the conjugated azo–ene system of 1,2-diaza-1,3-dienes. In alcohol it reacts as a nucleophile through the N-phenyl imino nitrogen affording spiro pyrroloimidazoles and 1,3-diphenyl-1H-imidazoles. In DMF, by contrast, it behaves as nucleophile mainly by means of the imino amidino nitrogen providing 2-phenylimidazole derivatives by loss of the aniline molecule.