Viologen-mediated reductive desulfonylation of α-nitro sulfones by sodium dithionite

Reductive desulfonylation of α-nitro sulfones to give the corresponding nitro compounds was carried out conveniently with sodium dithionite, by using octylviologen as an electron-transfer catalyst in organic solvent–water two-phase systems. Sulfones which do not have an α-nitro group are not desulfonylated. A reaction scheme involving a nitroalkyl radical has been proposed.