Reduction of 2α-nitro-5α-cholestan-3-one (4), its enol tautomer (3a) and 3-acetylamino-2-nitro-5α-cholest-2-ene (2) was studied. The latter compound was reduced with zinc in acetic acid to 3β-acetylamino-5α-cholestan-2-one (8). The similar reaction of 3a or 4 led to 2α-amino-5α-cholestan-3-one (11a), that may be trapped as N-formyl derivative. When crude 11a was subjected to air oxidation, pyrazino[2',3':2,3;5',6':2,3]bis(5α-cholestane) (9) was obtained.