The Shapiro Reaction, a variation on the Bamford-Stevens Reaction, is the base-induced reaction of tosylhydrazones to afford alkenes. This reaction is carried out with two equivalents of an organolithium compound.
Mechanism of the Shapiro Reaction
The advantage of the Shapiro over Bamford-Stevens Reaction is, that the resulting dianion does not tend to rearrange, which can occur with intermediate carbenes and carbenium ions. However, the Shapiro reaction does not lead to high stereoselectivity between the E-/Z-isomers.