Arenesulfonylhydrazones Bamford-Stevens reaction

Finally, hindered arenesulfonylhydrazones can undergo addition of the alkyllithium rather than deprotonation, and, in fact, the normal Shapiro conditions generally do not give any alkene if an a-methine proton must be removed in the initial deprotonation step. Shapiro reported that the use of LDA overcomes the problem,but there are later examples in which this modification is ineffective. In one such case, lithium t-butylamide proved to be superior (Scheme 72) and in another it proved necessary to re-son to the aforementioned N-aminoaziridine derivative in an aprotic Bamford-Stevens reaction, when the normal Shapiro and Bamford-Stevens conditions failed (Scheme 73). ... 

The Bamford-Stevens reaction is the base-catalyzed decomposition of arenesulfonylhydrazones of aldehydes and ketones, leading to the formation of alkenes an or cyclopropanes. There are several important general reviews in this area of organic synthesis. Since the reactions are mostly carried out either in protic or in aprotic solvents, the reaction types are divided into the protic and aprotic Bamford-Stevens processes. This section reviews recent examples in the synthesis of alkenes and cyclopropanes from arenesulfonylhydrazones, which is closely related to the following Shapiro reaction. 

The Bamford-Stevens reaction is the key step in a convenient procedure for the conversion of aldehydes and ketones into the corresponding diazoalkanes. Here, the use of 2,4,6-triisopropylbenzenesulfo-nylhydrazone (trisylhydrazone) is far superior to the use of the more common tosylhydrazones (equation 50). This behavior is attributed to the greater release of steric compression in the decomposition of ort/io-substituted arenesulfonylhydrazones. 

Bamford-Stevens and Shapiro Reactions. Thermal decomposition of the monoanions of arenesulfonylhydrazones in aprotic... 

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