Alkenes from Tosylhydrazones

In 1952, Bamford and Stevens observed that tosylhydrazones of aliphatic ketones yielded alkenes when treated with the sodium salt of ethylene glycol in boiling ethylene glycol. In addition to the alkene, molecular nitrogen, and p-toluenesulfinate anion were produced. This chapter reviews such syntheses of alkenes from tosylhydrazones and the formation of cyclopropanes and acetylenes from tosylhydrazones because the several reactions involved are so closely interrelated. The four major reaction types are reviewed here: (1) base-induced decomposition of tosylhydrazones in protic solvents and (2) in aprotic solvents (3) reactions of tosylhydrazones with alkyllithium reagents and (4) fragmentation reactions of alpha, beta-epoxytosylhydrazones and analogous systems. Reactions 1 and 2 are called the protic and aprotic Bamford-Stevens reaction.

Keywords: Bramford-Stevens reaction; tosylhydazones; alkyllithium reagents; protic reaction; aprotic reaction; fragmentation reactions; allenes; alkynes; cyclopropenes; alkanes; experimental procedures