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.

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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). "The decomposition of toluene-p-sulfonylhydrazones by alkali". J. Chem. Soc.: 4735–4740. doi:10.1039/JR9520004735.
2. ^ Shapiro, R. H. (March 1976). "Alkenes from Tosylhydrazones", Organic Reactions, 405–507. ISBN 0-471-19624-X. 
3. ^ Adlington, R. M.; Barrett, A. G. M. (1983). "Recent applications of the Shapiro reaction". Acc. Chem. Res. 16 (2): 55–59. doi:10.1021/ar00086a004.
4. ^ Creary, X. (1986). "Tosylhydrazone salt pyrolises: phenyldiazomethanes". Organic Syntheses 64: 207. (also in the Collective Volume (1990) 7:438 (PDF))

See also

• Shapiro reaction