Каталитическое гидрогенирование нитроалканов формиатом аммония.

Notes: Other catalysts can be used. Polymer supported Pd catalyst should
work. Raney Ni often works and Urushibara Ni should work as well
[but these are untested].

To a stirred suspension of an appropriate nitro compound (5 mmol) and 10%
Pd-C (0.2 - 0.3 g) [see Note 1] in dry methanol (10 mL), anhydrous ammonium
formate was added (23 mmol) in a single portion. The resulting reaction
mixture (slightly exothermic and effervescent) was stirred at room
temperature for 3-40 min under argon[see Note 2], the catalyst was removed
by filtration through a celite pad and washed with dry methanol (10 mL).
The filtrate was evaporated either under reduced or at normal pressure. The
resulting residue was triturated with water (10 mL - 25 mL), product was
extracted with an organic solvent (i.e. ether, DCM or chloroform) and dried
over Na2SO4. The organic layer on evaporation gave the desired amino
derivative. Some products were directly converted into the HCl-salt with
ethereal-HCl without evaporation of ether layer.

In most cases the reaction is over within 15-30 min with nitro-alkanes.
These results demonstrate a rapid versatile and selective reducing system
for wide variety of nitro-compounds in the presence of other functional
groups for e.g. -CN. > C=O, etc. Ammonium formate also has the advantages
of being readily available, inexpensive, stable and nontoxic and can be
used in conjunction with either Pd-C or Raney-Nickel catalysts. Moreover,
it may be added to the reaction in a single portion and products can be
easily separated from the reaction mixture. This procedure will therefore
be of general use for the preparation of amines specifically in cases where
rapid mild reduction is required.