A general procedure for mild and rapid reduction of aliphatic and aromatic nitro compounds using ammonium formate as a catalytic hydrogen transfer agent

Abstract

Various aliphatic and aromatic nitro compounds were selectively and rapidly reduced to their corresponding amino derivatives in very good yield using anhydrous ammonium formate as a catalytic hydrogen transfer agent. Selective and rapid reductLon of nitro compounds is still area of considerable synthetic interestl, particularly when a molecule has several other reducible moieties. Numerous new reagents*-l4 have been developed for reduction of aromatic nitro compounds, however little attention has been paid to the reduction of aliphatic nitro compound&ry,S, which are traditionally reduced by high pressure catalytic hydrogenation 15,16* In the past 30 years catalytic transfer hydrogenation 17-** has demonstrated great potential value in organic and biological chemistry.

Zinc dust-mediated reductive degradation of decabromodiphenyl ether

“…Thus, a likely mechanism would involve a SET from the metal, either directly or indirectly via electron carrier, to produce a radical anion, subsequent dissociation into an aryl radical and a halide anion, followed by a second SET to the anion (41), which is protonated in the final step. It is known that ammonium formate plays the role of an effective proton transfer agent (42). When the quantity of ammonium formate was increased (to 10 eq.)…”

A General Synthetic Approach to the (20S)-Camptothecin Family of Antitumor Agents by a Regiocontrolled Cascade Radical Cyclization of Aryl Isonitriles

“…The requisite -catalyzed cleavage of hexamethyldisilane [37] with 32 provided nitroarylsilane 33 in 64 % yield. This intermediate was reduced quantitatively under classical conditions [38] and the resulting free amine 34 was formylated with formic acid/dicyclohexylcarbodiimide (DCC) [39] followed by dehydration [34b] to provide 35 in 90 % yield. The radical cascade of the model pyridone 9 c with 35 proceeded very cleanly to give a single isomeric tetracycle 11 g in 46 % yield.…”

Synthesis of C3/C1-Substituted Tetrahydroisoquinolines

“…To achieve the reduction of the α,β-unsaturated nitro group, common literature methods [35] entail the use of LiAlH4 and lead to very low yield reactions. The use of anhydrous ammonium formate in conjunction with Pd-C catalyst gave the oxime derivatives as the main products [35].…”

“…To achieve the reduction of the α,β-unsaturated nitro group, common literature methods [35] entail the use of LiAlH4 and lead to very low yield reactions. The use of anhydrous ammonium formate in conjunction with Pd-C catalyst gave the oxime derivatives as the main products [35]. Good results in our case were obtained by a "step by step" selective reduction procedure based on the catalytic hydrogenation of the alkene functionality at room temperature (TLC monitoring) followed by the reduction of the aliphatic nitro group by adding to the reaction mixture ammonium formate and raising the temperature to reflux.…”