Sulfones with a good leaving group in the β position may undergo reductive elimination under desulfonylation conditions to afford alkenes. This process is a key step of the Julia olefination, which yields alkenes via addition of an α-sulfonyl carbanion to an aldehyde followed by reductive elimination. Sodium amalgam or samarium(II) iodide/HMPA may be used to convert β-sulfonyloxy or β-acyloxy sulfones to the corresponding alkenes. The key mechanistic step of this process is elimination of an anionic or organometallic intermediate to generate the alkene.
The use of sodium amalgam, which promotes the formation of essentially free alkyl anions, leads to (E) alkenes with extremely high selectivity. Samarium(II) iodide also produces the (E) alkene predominantly, but with lower selectivity.