Chemoselective Reductions of Nitroaromat

A robust and green protocol for the reduction of functionalized nitroarenes to the corresponding 1° amines has been developed. It relies on inexpensive zinc dust in water containing nanomicelles derived from the commercially available designer surfactant TPGS-750-M. This mild process takes place at room temperature and tolerates a wide range of functionalities. Highly selective reductions can also be achieved in the presence of common protecting groups. Aromatic and heteroaromatic primary amines have proven to be important building blocks in the synthesis of a wide range of pharmaceuticals, polymers, and fine chemicals, with particular utility in cross-coupling reactions. However, the inherent reactivity of this functional group often requires protection from premature participation in multi-step syntheses. One popular strategy involves their masking as nitroarenes, which provides multiple benefits, including facile nitrogen introduction via early stage nitration, excellent atom economy, and directed arene functionalization resulting from the associated electronics of the nitro moiety. However, this protection strategy introduces a challenge: the required chemoselective reduction of nitroarenes in the presence of other functional groups. Classical reductions have often relied on harsh conditions, but this new approach mitigates safety and environmental concerns while expanding substrate scope.