06-12-02 07:42
No 320241
      Ketones from nitroalkenes
(Rated as: excellent)

This one is from Tet. Lett. vol 24, No 4, page 417-418, 1983.

Nitroolefines are converted to the corresponding saturated ketones or aldehydes in high yields by treatment with raney nickel and sodium hypophosphite in aqueous ethanol at pH 5.

General experimental procedure:

a suspension of raney nickel (2,5ml) and an aquoeous solution of sodium hypophosphite (14g in 60ml water) were added (in serveral portions and under stirring) to a solution of the nitroolefin (14mmol) in ethanol-aqueous acetate buffer, pH 5 (2:1 ca 400ml). After 2 hours at 40-50 deg C the catalyst was filtered off, water added and the solution extracted with ether. Evaporation of the solvent yielded the carbonyl compound that could be purified by either distillation or crystallisation.

It must be pointed out that under these conditions nitroparaffins are reduced to amines whilst oximes gives the corresponding carbonyl compounds in almost quantitative yields. Ester groups, C=C bonds, nitro and halogen substituents on aromatic nuclei are not affected by this reducing system.

        1-Phenyl-2-nitropropene gives P-2-P in 88% yield
1-(p-MeO-phenyl)-2-nitropropene gives p-MeOP-2-P in 92% yield
1-(p-Br-phenyl)-2-nitropropene gives p-BrP-2-P in 77% yield
1-(o-OH-phenyl)-2-nitropropene gives o-OHP-2-P in 70% yield
1-(p-OH-phenyl)-2-nitropropene gives p-OHP-2-P in 56% yield
1-(p-MeO-phenyl)-2-nitroethene gives p-MeO-phenylacetaldehyde in 53% yield

I have not had the time to try this yet. I found this article yesterday.... laugh

If it works it should make 2C-X and DOX within reach by condensation of the benzaldehyde (with everything in place) with nitromethane/ethane..reduction/hydrolysis to the carbonyl and reductive amination to the amine with cyanoborohydride or triacetoxyborohydride.tongue