Samarium(0) and 1,1‘-Dioctyl-4,4‘-Bipyridinium Dibromide:  A Novel Electron-Transfer System for the Chemoselective Reduction of Aromatic Nitro Groups

Abstract

A mild and efficient electron-transfer method was developed for the chemoselective reduction of aromatic nitro groups using samarium(0) metal in the presence of a catalytic amount of 1,1'-dioctyl-4,4'-bipyridinium dibromide. This method was found to give the product aromatic amine in 79-99% yield with selectivity over a number of other functional and protecting groups such as alkene, azide, benzyl ether, nitrile, amide, halide, p-toluenesulfonamide, t-Boc, tert-butyldiphenylsilyl ether, and aliphatic nitro groups. Our results also indicate that samarium(0) plays an important role in the reduction process and that 1,1'-dioctyl-4,4'-bipyridinium dibromide acts as an electron-transfer catalyst and is essential in the activation of samarium(0) metal. The major active reducing agent responsible for the reduction is believed to be the radical cation species formed from 1,1'-dioctyl-4,4'-bipyridinium dibromide.

Highly Chemo‐ and Regioselective Transfer Reduction of Aromatic Nitro Compounds using Ammonium Formate Catalyzed by Supported Gold Nanoparticles

“…In addition, the reduction of aromatic nitro compounds often stops at an intermediate stage, yielding hydroxylamine, hydrazine, and azoarene products. [9] In this sense, there is a strong incentive to develop new simple, efficient, easily-handled procedures that can allow the highly chemo-and regioselective reduction of the nitro group under mild conditions.…”

“…Many conventional procedures involving hydride reducing agents, hydrogenation, or indium failed to give such a high regioselectivity. [9,15] Recently, the regioselective reduction of [f]…”

Chemo‐selective reduction of nitro and nitrile compounds using Ni nanoparticles immobilized on hyperbranched polymer‐functionalized magnetic nanoparticles

“…The Chloroand fluoro-substituted nitroarenes (Table 2, entries 3 and 4) were selectively reduced to the respective haloaromatic amines without any dehalogenation, which is often encountered with several procedures such as hydrogenation. [68][69][70][71] An analysis of the results of Table 2 shows that the best yields were obtained with substrates containing electron-withdrawing groups (entries 5-8). The ketone, carboxylic acid, and aldehyde functionalities present in the aromatic ring also remained unaffected during reduction of the corresponding nitrobenzenes by this procedure (entries 5-8).…”

A highly effective Ag–RANEY® nickel hybrid catalyst for reduction of nitrofurazone and aromatic nitro compounds in aqueous solution

“…Formation of such intermediates is oen observed with many other reducing agents. 16,30 When nitrosobenzene or phenylhydroxylamine was treated with Ag-RANEY® nickel and NaBH 4 in aqueous solution at 35 C, the nal product was aniline and it can be concluded that the following reaction path rationalized the overall reduction.…”