Synthesis of 2-Substituted Benzimidazole-5-carbamates as Potential Antifilarial Agents

A large group of benzimidazole derivatives are highly effective as an anthelmintics [ 11. Among these, mebendazole (la, methyl 5-benzoylbenzimidazole-2-carbamate) and flubendazole (lb, methyl 5-p-fluorobenzoylbenzimidazole-Z-carbamate) have demonstrated a broad-spectrum of activity against helminth diseases including filarial infections [2-51. In our continuing studies to develop new antifilarial agents [6-81, we have found that two of the metabolites of mebendazole, methyl 5-(c~-hydroxylbenzyl)benzimidazole-2-carbamate (lc), and, methyl 5-benzylbenzimidazole-2-carbamate (la) possess antifilarial activity very similar to that of the parent drug l a [9]. Recently, a series of benzothiazoles, typified by structure 2, were