10.1007/s00706-002-0549-9
The study focuses on the selective reduction of an aromatic nitro group to an azoxy unit in the presence of an aliphatic nitro group, which is significant for the synthesis of aromatic azoxy compounds due to their physiological activities and applications in liquid crystal systems. The researchers used sodium borohydride in methanol with substoichiometric amounts of bismuth as the reducing agents to achieve chemoselective reduction of 1-nitro-2-(2-nitro-2-methylpropyl)-benzene to 2,20-di-(2-nitro-2-methylpropyl)-azoxybenzene. This method was compared to the reduction with zinc in hydrochloric acid, which resulted in a mixture of products and poor reproducibility. The purpose of the chemicals used was to selectively reduce the aromatic nitro group without affecting the aliphatic nitro group, and the study successfully demonstrated the first example of such a transformation.