Efficient Access to o‐Phenylendiamines and Their Use in the Synthesis of a 1,2‐Dialkyl‐5‐trifluoromethylbenzimidazoles Library Under Microwave Conditions

A quick access toward a 1,2‐dialkyl‐5‐trifluoromethylbenzimidazoles library by a three‐step synthesis sequence starting from 1‐chloro‐2‐nitro‐4‐(trifluoromethyl)benzene is described. The synthesis proceed via o‐phenylendiamines eficiently isolated, which also are key synthetic intermediates of another valuable heterocyclic compounds. Likewise, the trifluoromethyl group is part of the obtained benzimidazoles, affording an important structural feature for their possible applications. The advantages of this methodology are the modular lipophilicity of products, easy work‐up, up to 83% overall yield, the convenient use of microwave‐assisted reactions, and the production of compounds (intermediates and products) of high‐added value using cheap reagents and simple protocols. A efficient access toward 1,2‐dialkyl‐5‐trifluoromethylbenzimidazoles from 1‐chloro‐2‐nitro‐4‐trifluoromethylbenzene and primary alkylamines via a three‐step synthesis sequence involving ArNS, reduction and cyclocondensation with orthoesters is described. In addition, o‐phenylendiamines corresponding were efficiently isolated, which are key synthetic intermediates of another valuable heterocyclic compounds.