Syntheses of condensed imidazoles by lead tetraacetate oxidation of amidines

2-Phenylbenzimidazoles, 2-benzylbenzimidazoles, 2-phenyl-1H-naphtho[1,2-d]imidazole, and 2-benzyl-1H-naphtho[1,2-d]-imidazole have been synthesized in excellent yields (77–98%) by lead tetraacetate oxidation of suitable N-arylbenzamidines, N-arylphenylacetamidines, N-α-naphthylbenzamidine, and N-α-naphthylphenylacetamidine respectively. The mechanism of nitrene insertion and intramolecular competitive nitrene insertion leading to these heterocycles has also been discussed.