Tosylhydrazones give alkenes upon treatment with strong bases. This reaction is performed in two steps, where the intermediate diazo compound may be isolated. Subsequent reaction with protic or aprotic solvents strongly influences the outcome of the reaction.
This reaction may be used to effect the overall transformation of a ketone to an alkene.
If an organolithium is used as the base, the reaction follows another mechanism without occurrence of carbenium ions and carbenes (see Shapiro Reaction).
Mechanism of the Bamford-Stevens Reaction
Carbenium ions are formed in protic solvents:
...and carbenes in aprotic solvents: