Nitration of 2,3-dihydroimidazo[1,2-a]benzimidazole and its N 9-substituted derivatives

7-Nitro-2,3-dihydroimidazo[1,2-a]benzimidazole and its N9-substituted derivatives can be conveniently synthesized by nitration of the corresponding tricyclic precursors with a nitrating mixture or with the HNO3 /CF3COOH system. This reaction occurs fairly smoothly and with good regioselectivity.