Twelve -substituted--dialkylaminomethyl benzimidazoles (Ⅱ_(a-)) have been synthesized by "reductive cyclization" of the 十二种-取代的-硝基-(二烴胺基乙酰)苯胺(Ⅰ_(a-))在稀醋酸中以次硫酸鈉处理,一步“还原环化”成相应的-取代的-二煙胺甲基苯并咪唑(Ⅱ_(a-))。