TsCl-promoted thiolation of quinoline <i>N</i>-oxides with thiophenols.

A metal-free method for the regioselective synthesis of 2-thiolated quinolines from quinoline <i>N</i>-oxides in water at room temperature is developed. The reaction is conducted using benzenethiols as thiolation reagents in the presence of <i>p</i>-toluenesulfonyl chloride <i>via p</i>-toluenesulfonyl chloride-assisted tandem C-H bond activation, nucleophilic addition, deoxygenation and aromatization processes. This method does not require the use of metal catalysts and oxidants. It shows the advantages of wide functional group tolerance, short reaction times and simple operation.