4-diaza-1,3-butadiene (L1) was separated from a condensation reaction of benzil with N-tosyl-ethylenediamine. It was shown that the intramolecularcyclization of L1 has much dependence on the transitionmetal salts. The transformation of L1 in the absence of any transitionmetal salts gave product 1-tosylaminoethyl-2-tosylaminomethyl-4,5-diphenyl-1H- imidazole (L2) at a temperature above 100 °C. Similar