Synthetic Routes to Symmetric Bisbenzimidazoles: A Review

Bisbenzimidazoles, have shown various biological activities viz. antineoplastic, anti-tumor, anti-fungal, anti-inflammatory, hypoglycemia treatment and physiological disorders, besides other pharmacological effects. Structural modifications of the benzimidazole nucleus are being carried out in several ways in order to anticipate enhanced biological activities. The synthesis of bis-benzimidazoles is one such attempt, where the two benzimidazole nuclei are united together using a variety of linkers and points of linkages. These structural permutations and combinations have given a large number of available bisbenzimidazole compounds for pharmacological and biological research. A number of reviews have been published over the past decade on the compilation of the biological activities of bisbenzimidazoles. However, we could not locate any report covering the general strategies followed for the synthesis of these compounds. The present review provides an in depth view of synthetic routes for preparation of symmetric bisbenzimidazoles.