Aluminum amalgam for the reduction of sensitive β-nitroamines to 1,2-diamines

A two-step reduction protocol for the conversion of a range of sensitive beta-nitroamines to 1,2-diarnines has been developed that is operationally simpler, cheaper and higher-yielding than the previously reported SmI2 protocol. Reduction of the nitro function to a hydroxylamine was achieved with Al amalgam and then reduced to the 1,2-diamine product with H-2, Pd/C or LiAlH4 with no erosion of diastereoselectivity. A representative selection of 9 beta-nitroamines were reduced in 71-94% yield.