Mg, Al, Fe and Zn can all be used together with a acid to reduce nitroalkanes to aminoalkanes. The difference is the yield and the agony associated with the workup.

In

Chem. Pharm. Bull., 1979, 27(1), 198-203

(http://www.angelfire.lycos.com/scifi2/lego/journals/13.djvu) the reduction of the double bond of phenylnitropropenes is described.

Formic acid reduction of beta-nitrostyrenes
General procedure

---

A mixture of Ia - f and 5.2 g (0.06 mol based on HCOOH) of TEAF in 40 ml of DMF was stirred at appropriate temperature. Dry air free from CO₂ was introduced in order to check evolution of CO₂ by saturated Ba(OH)₂ solution. After CO₂ evolution almost ceased, DMF and excess TEAF were destilled off under reduced pressure. The residue was dissolved in benzene. The benzene solution was washed with water and dried over anhyd. MgSO₄. Evaporation of benzene under reduced pressure gave the crude reaction product. Recrystallization or distillation under reduced pressure gave pure reduction product. In the run with If, the production was purified was purified by passing through a basic column using benzene-ethyl acetate as an eluent. Physical and analytical data of the reduction products are summarized in Table III.

---

Yield for P2NP (phenylnitropropene): 70%, reaction time: 6.0 h, reaction temp: 120-122 °C




Note: This will not work for nitrostyrenes!



Preparation of TEAF (adopted from Chem. Pharm. Bull., 1977, 25, 135-140):

A mixture of 80% formic acid and trialkylamine (triethylamine), roughly in the azeotropic molar properties, was carefully distilled under a reduced pressure. After removal of a lower boiling distillate, a fraction at constant higher boling temperature was collected. This distillate was dried over anhydrous MgSO₄ an redistilled.



In the above reaction 5.2 g of the azeotrope are used, equal 0.06 mol HCOOH (2.76 g). Therefore 2,44 g of TEA should be added carefully to 2.76 g of pure formic acid or a solution in water containing 2.76 g of pure formic acid.



A formic acid:triethylamine 5:2 solution is commercially available.

Great post!

A Highly Chemoselective Reduction of Conjugated Nitro Olefins with Hantzsch Ester in the Presence of Silica Gel
M. Fujii
Bull. Chem. Soc. Jpn., 61, 4029-4035 (1988).
https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000352950-BCSJ1988_61_4029.djvu" target="_blank" title="Download this file">

Abstract:
   An effective system to reduce conjugated nitro olefins into the corresponding nitroalkanes is described. The system composed of Hantzsch ester (HEH) and silica gel in benzene exerts high yield and excellent chemoselectivity under almost neutral conditions. Facile applications of the system to the syntheses of natural products are also described.

An earlier work by the same author is mentioned in

Post 352991

(foxy2: "More novel nitrostyrene to nitroalkane", Novel Discourse).