A new two-step synthesis of N,N′-disubstituted2,2′-biimidazoles from bisimidoyl chlorides is reported. The bisimidoyl chlorides react smoothly with (2,2-dimethoxyethyl)amine to give bisamidines that are subsequently cyclized to give the corresponding biimidazoles. acetals - biimidazole - heterocycles - cyclization - diazadiene complexes