The Bamford-Stevens reaction is the formation of an alkene by the treatment of the tosylhydrazone of an aldehyde or a ketone with a base. A few diazo compounds can be isolated if mild temperature is employed; however in the majority of cases the diazo compounds thermally decompose to form alkenes.
The titled reaction was first reported by William Randall Bamford and Thomas Stevens Stevens in 1952 at the University of Sheffield. It is closely related to the Shapiro reaction, in which tosylhydrazones are treated with alkyl lithium reagents to form alkenes.
Bamford Stevens Reaction MechanismBack to Top
The first step of the Bamford-Stevens reaction is the formation of the diazo compound via the tosylate salt.
The mechanism for alkene formation was found to be dependent upon the reaction conditions. The diazo compound can be protonated to form a diazonium ion, resulting in the formation of a carbocation upon loss of dinitrogen.
This pathway does not occur in the absence of protons, and in aprotic medium, dinitrogen loss results in the formation of carbene intermediates.
The migration of hydrogen may immediately follow, or to be simultaneous with the loss of dinitrogen.