From tosylhydrazones

The alternative route, from tosylhydrazones 8 by treatment with base, usually morpholine, has been used for high yields of sensitive materials. Examples are the 7-acetylamino derivatives 9a and 9b (89T7041) and the 5-bromo derivative... 

A more promising procedure for the formation of alkenes from tosylhydrazones is represented by the Shapiro reaction It differs from the Bamford-Stevens reaction by the use of an organolithium compound (e.g. methyl lithium) as a strongly basic reagent ... 

The sulfur ylide-mediated epoxidation of aldehydes has been thoroughly investigated [70, 71]. The chiral sulfur ylides reported by Aggarwal have been most broadly applicable, and a catalytic, asymmetric process yielding aromatic transepoxides has been developed [72]. In this process, the sulfur ylides are produced in situ from diazo compounds, generated in turn from tosylhydrazone salts (Scheme 9.15) [73],... 

Olefins, conversion to alcohols, 53, 94 from tosylhydrazones and methyllithium, 51, 69 hydroboration-oxidation of,... 

As a result, trisylhydrazones 95 allow the use of just 2 equivalents of alkyllithinm, and thus only a single equivalent of electrophile (E) is needed to trap the resultant vinyllithinm 97 to form the functionalized aUtene 98. Moreover, trisylhydrazone dianions 96 nndergo the elimination reaction much faster than do those derived from tosylhydrazones. This rate enhancement allows the use of even more acidic solvents, such as tetrahydrofuran. 

Regeneration of ketones from tosylhydrazones with Oxone in acetone has been reported. Under controlled pH (pH = 6) the reaction gave very high yield (90%) of the product. In this paper we demonstrated that the use of in situ formed dimethyldioxirane under controlled pH conditions gives better results (equation 66). 

As in the epoxidation reactions, the diazo compound could be generated in situ from tosylhydrazone salts (see Scheme 10.16) [79, 80]. This addressed the major... 

V thermal decomposition of diazo compound, often derived from tosylhydrazone... 

The synthesis of methanofullerenes 955 was achieved starting from / -tosylhydrazones 954 and Cso under basic conditions (toluene, 70 °C). Tosylhydrazones 954 were prepared from the respective aldehydes 953 and />-toluene sulfonylhydrazide (Scheme 146) <2000CC113>. 

The problem necessitating the use of excess n-BuLi, and consequently an excess of the electrophile, was obviated by using ketone-derived 2,4,6-triisopropylbenzene-sulfonylhydrazones (trisylhydrazones). Elimination to give the carbanion intermediate is much faster with the trisylhydrazone-derived dianion than with that obtained from tosylhydrazones, presumably because of relief of strain. This shortens the time of exposure of the carbanion to the solvent, thereby reducing the chance of its protonation before it can be trapped by an electrophilic reagent. 

Regeneration of carbonyl compounds from tosylhydrazones. The rapid hydrolysis is carried out in methanol at room temperature (9 examples, 75-93%). 

The cycloaddition of diazoalkanes to alkynes gives pyrazoles the use of stannyl alkynes ° produces tin derivatives of the heterocycle (cf. 4.1.6), for use in subsquent electrophilic ipio-displacements, or in palladium(0)-catalysed couplings. Aryl-diazomethanes can be generated in situ, from tosylhydrazones, for formation of pyrazoles. ... 

The mechanism of the Shapiro reaction is believed to involve initial deprotonation of the NH proton from tosylhydrazone 5 to generate 6, which undergoes a second deprotonation adjacent to the hydrazone group to afford dianion 7. Elimination of lithium p-toluene-... 

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