Decomposition of tosylhydrazones of benzoin, benzoin acetate, and benzoin benzoate with alkali and metal complex hydrides

Abstract

Treatment of tosylhydrazones of benzoin, benzoin acetate, and benzoin benzoate with alkali under protic and aprotic conditions yielded diphenyl acetylene together with desoxybenzoin. An increase in leaving aptitude of the adjacent group enhanced the formation of diphenyl acetylene. By treatment with LiAIH, and with NaBH,, the tosylhydrazones gave stilbenes in good yields. Selective formation of cis-or trnns-stilbene was observed in some cases.

Acyclic 1,4-Stereocontrol via the Allylic Diazene Rearrangement: Development, Applications, and the Essential Role of Kinetic E Stereoselectivity in Tosylhydrazone Formation

“…There are a just a handful of reports of the preparation of acyclic α-alkoxy sulfonyl − or acyl , hydrazones from ketones, and only a few that report the hydrazone E/Z -configurations. − Alami et al reported a 1.5–5.7:1 Z:E ratio of hydrazones 15 depending upon the identity of R 1 and R 2 (Figure ). The hydrazones were prepared by stirring the ketones with TsNHNH 2 in methanol at ambient temperature.…”

Thermal rearrangement of some benzoin arylsulfonylhydrazone derivatives

“…Also, photochemical decomposition of benzocyclobutenone p-toluenesulfonylhydrazone led to E-and Z-isomers of 1,1-bi(benzocyclobutenylidenes) as the major products in addition to a wide variety of products [4]. Furthermore, it has been reported that the decomposition of tosylhydrazones of benzoin and benzoin acetate and benzoin benzoate under protic and aprotic conditions with alkali yielded diphenyl acetylene together with deoxybenzoin by an obscure mechanism [5]. This finding prompted us to reinvestigate of thermolysis of these compounds to gain further insight into the mechanism of fragmentation.…”