Studies of Organosulfur Compounds. VI. : On the Preparation of N-Substituted-2-(2-pyridyl) benzimidazoles

Abstract

In connection with the synthesis of 2-(2-pyridyl) benzimidazole derivatives with a substituent in 1-position, reactivity of vinylpyridines and vinyl cyanide was examined. The reaction was found to progress smoothly when glacial acetic acid is used as a catalyst with vinylpyridines and a quaternary salt for vinyl cyanide, affording the desired 1-(2-pyridylethyl) and 1-(2-cyanoethyl)-2-(2-pyridyl) benzimidazoles, respectively. In order to convert the cyano group into acid amide derivatives, hydrolysis with acid or alkali was examined and a reaction whereby the acid amide compound (VIb) and carboxylic acid (VIc) are obtained at the same time was established. Hydrolysis by the use of barium hydroxide, however, resulted in dealkylation from the nitrogen in 1-position to produce the starting material. Hydrolysis with hydrochloric acid did not produce this dealkylation.