A facile synthesis of 2-acyl and 2-alkylaminobenzimidazoles for 5-lipoxygenase inhibitors

2-Acylaminobenzimidazoles (2a-r) have been synthesized from o-phenylenediamines (4) with benzoylcarbonimidodithioic acid dimethyl ester (5a) or isobutyrylcarbonimidodithioic acid dimethyl ester (5b) in good yield. 2-Alkylaminobenzimidazoles could be prepared by the reaction of o-Phenylenediamines (4a, b) with benzyl isothiocyanate in moderate yields 8a, b or the reaction of 2-chlorobenzimidazole (9) with benzylamines (10a, b) in moderate yield 11a, b. Finally, the carbamate derivative of 2-aminobenzimidazole (13) was prepared by the reaction with pseudourea (12) in low yield. Most of the prepared analogues were evaluated in leukotriene inhibition assay and it found that benzamide derivatives (2a-i) are quite active among others.