Iron and copper catalyzed reaction of benzylamine with carbon tetrachloride: facile formation of 2,4,5- triphenylimidazoline derivatives

Iron and copper salts catalyzed the reaction of benzylamine with CCl₄ to give a mixture of 2,4,5-triphenylimidazole (1), 1-benzyl-2,4,5-triphenylimidazole (2), 2,4,5-triphenylimidazoline (3), and 1-benzyl-2,4,5-triphenylimidazoline (4) in high yields. The imidazoline 4 was obtained as the main product. The imidazole and imidazoline derivatives were also formed by the iron-catalyzed reaction of benzylidenebenzylamine (8) or dibenzylamine (5) with CCl₄. The imidazoline 4 slowly underwent debenzylation and dehydrogenation with the aid of CCl₄ and iron catalyst to give 1 and 2. From these results, a mechanism involving formation of 5 and 8, subsequent oxidative dimerization of 5 and 8 to form 4, and further conversion of 4 to 1, 2, and 3 is proposed.