Studies on 2-Benzimidazolethiol Derivatives. I: Synthesis and Analgesic Effects

The tosylated o-nitroaniline (I) was condensed with 2-diethylaminoethyl chloride and N-(2-diethylaminoethyl)-2-nitroaniline (IV) was obtained, after the detosylation with conc. sulfuric acid. The nitro group of (IV) was reduced with stannous chloride and hydrochloric acid to N-(2-diethylaminoethyl)-o-phenylenediamine (V), which was condensed with carbon disulfide into 1-(2-diethylaminoethyl)-2-benzimidazolethiol (VI). When the potassium-salt of (VI) was reacted with the corresponding halides in either ethanol, benzene or xylene, 11 kinds of new substances were obtained. The analgetic effect of these derivatives was studied by the D'Amour-Smith method, and the substitution of hydrogen in the thiol group with methylene was found to give a decrease of the action generally, though (VI) showed a slight action.