Non-Catalyzed Reductions With Formate Salts: Conversion of Nitroaromatic Compounds to the Corresponding Primary Amines

Abstract
One of the more important transformations in aromatic chemistry involves nitration of the ring followed by reduction1 of the nitro group to the corresponding primary amine. Despite its low cost, ease of handling, and known2 property of being a convenient hydrogen donor, formic acid (or formate salts, which are even more active hydride donors2) was not utilized for this reduction until recently when Heck and Cortese reported 3 the palladium-catalyzed reduction of nitroaromatics using triethylammonium formate. Since the latter reagent in N,N-dimethylformamide (DMF) had previously4 been shown to reduce the carbon-carbon double bond in good Michael acceptors without the presence of a metal catalyst, we decided to examine non-catalytic systems involving formic acid5 for effecting reduction of the nitro group.