Bamford–Stevens reaction

The Bamford–Stevens reaction is a chemical reaction whereby treatment of tosylhydrazones with strong base gives alkenes.^[1][2][3] 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.^[4]

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

1. ^ Bamford, W. R.; Stevens, T. S. (1952). "924. The decomposition of toluene-p-sulphonylhydrazones by alkali". Journal of the Chemical Society (Resumed): 4735. doi:10.1039/JR9520004735.  edit
2. ^ Shapiro, R. H. (March 1976). "Alkenes from Tosylhydrazones". Organic Reactions. 23. New York: Wiley. pp. 405–507. ISBN 0-471-19624-X. 
3. ^ Adlington, R. M.; Barrett, A. G. M. (1983). "Recent applications of the Shapiro reaction". Accounts of Chemical Research 16 (2): 55. doi:10.1021/ar00086a004.  edit
4. ^ Creary, X. (1986). "Tosylhydrazone salt pyrolises: phenyldiazomethanes". Organic Syntheses 64: 207. http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0438.  (also in the Collective Volume (1990) 7:438 (PDF))

See also

• Shapiro reaction