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DOI: 10.1055/sos-SD-047-00322

Kostikov, R. R.; Khlebnikov, A. F.; Sokolov, V. V.Science of Synthesis, (201047853.

Ketone (arylsulfonyl)hydrazones 152 are transformed into alkenes 155 in a multistep reaction upon heating with sodium or potassium alkoxide at temperatures of 140160°C; this is known as the BamfordStevens reaction.[‌333‌‌335‌] The transformation is initiated by the formation of an aliphatic diazo compound 153 upon treatment of the hydrazone with base. The diazo compound then decomposes to a carbene intermediate 154, which rearranges by β-hydrogen migration to give an alkene (Scheme 56). A modification of this reaction works with the initial formation of a metal (Li, Na, K) salt by deprotonation of the hydrazone with an alkyllithium reagent or with sodium or potassium hydride and subsequent thermolysis of that salt. Shapiro has suggested a methodology involving the reaction of a tosylhydrazone with a two- to threefold excess of an alkyllithium reagent. This so-called Shapiro reaction proceeds at temperatures as low as room temperature.[‌336‌‌339‌]

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