Bamford-Stevens reaction

The Bamford-Stevens reaction is a chemical reaction whereby treatment of tosylhydrazones with strong base gives alkenes.cite journal | author = Bamford, W. R.; Stevens, T. S. | journal = J. Chem. Soc. | date = 1952 | pages = 4735–4740 | title = The decomposition of toluene-p-sulfonylhydrazones by alkali | doi = 10.1039/JR9520004735] cite book | last = Shapiro | first = R. H.| title = Organic Reactions | date = March 1976 | volume = 23 | pages = 405–507 | chapter = Alkenes from Tosylhydrazones | id = ISBN 0-471-19624-X ] cite journal | author = Adlington, R. M.; Barrett, A. G. M. | journal = Acc. Chem. Res. | date = 1983 | volume = 16 | issue = 2 | pages = 55–59 | title = Recent applications of the Shapiro reaction | doi = 10.1021/ar00086a004] It is named for the British chemist William Randall Bamford and the Scottish chemist Thomas Stevens Stevens (1900-2000). The usage of aprotic solvents gives predominantly Z-alkenes, while protic solvent gives a mixture of E- and Z-alkenes.

The treatment of tosylhydrazones with alkyl lithium reagents is called the Shapiro reaction.

Reaction mechanism

The first step of the Bamford-Stevens reaction is the formation of the diazo compound 3.cite journal | last = Creary | first = X. | title = Tosylhydrazone salt pyrolises: phenyldiazomethanes | journal = Organic Syntheses | Coll. | volume = 64 | pages = 207 | date = 1986 | url = http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0438 ("also in the [http://www.orgsyn.org/orgsyn/pdfs/CV7P0438.pdf Collective Volume (1990) 7:438] (PDF)")]

In protic solvents, the diazo compound 3 decomposes to the carbenium ion 5.

In aprotic solvents, the diazo compound 3 decomposes to the carbene 7.

References

ee also

* Shapiro reaction