DNA-Compatible Nitro Reduction and Synthesis of Benzimidazoles.

A key factor for productive DNA-encoded libraries is the chemical diversity of the small molecule moiety attached to an encoding DNA oligomer. The library structure diversity is often limited to DNA-compatible chemical reactions in aqueous media. Herein, we describe a facile process for reducing aryl nitro groups to aryl amines by using sodium dithionite (NaSO). The new protocol offers simple operation and circumvents the pyrophoric potential of the conventional method (Raney nickel). The utility of this method is demonstrated by the versatile synthesis of benzimidazoles on DNA.