From tosylhydrazones and

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

Regeneration of the parent carbonyl compound from tosylhydrazones and 2,4-dinitrophenylhydrazones can be carried out in high yield using sodium nitrite in trifluoroacetic acid. Deprotection of tosylhydrazones using thallium triacetate in acetic add is also elficient. Oximes yield the carbonyl product on treatment with bromine in aqueous sodium bicarbonate, and the same conditions can be used to hydrolyse tosylhydrazones if HMPA is present. Aqueous nitric acid was found to be superior to both sulphuric and hydrochloric adds for the cleavage of the hydrazones (90) to the corresponding cyclohexanones. ... 

The alkyl lithium method gives high yields of -olefins from 17-ketones via the tosylhydrazones. A -Olefins are formed from 6- and 7-ketones. (Compare with the Bamford-Stevens reaction which gives A - and A -olefins, respectively.) In the presence of an excess of alkyl lithium, alkylation may occur. 

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... 

Of course, the key limitation of the ylide-mediated methods discussed so far is the use of stoichiometric amounts of the chiral reagent. Building on their success with catalytic asymmetric ylide-mediated epoxidation (see Section 1.2.1.2), Aggarwal and co-workers have reported an aza version that provides a highly efficient catalytic asymmetric synthesis of trans-aziridines from imines and diazo compounds or the corresponding tosylhydrazone salts (Scheme 1.43) [68-70]. 

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],... 

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. 

Methylcyclohexene, from 2-methyl-cyclohexanone tosylhydrazone and methyllithium, 51,69 Methylenecyclopropanes, 50,30 Methyl iodide, with triphenyl phosphite and cyclohexanol, 51,45 with triphenyl phosphite and neopentyl alcohol, 51,44 METHYL ftrans-2-IODO-l-TETRA-LIN)CARBAMATE, 51,112 Methyl (frans-2-iodo-l-tetralin)carba-mate, with potassium hydroxide to give 1,2,3,4-tetrahydronaph-thalene(l,2)imine, 51,53 Methyllithium, with camphor tosylhydrazone to give 2-bomene, 51, 66... 

The reduction of tosylhydrazones by complex metal hydrides has been used very effectively to prepare saturated steroid hydrocarbons in high yields.317 In certain cases this reduction (with lithium aluminum hydride) takes a different course, and olefins are formed.318 The effect is dependent on both the reagent concentration and the steric environment of the hydrazone.319 Dilute reagent and hindered hydrazone favor olefins borohydride gives the saturated hydrocarbon. The hydrogen picked up in olefin formation comes from solvent, and in full reduction one comes from hydride and the other from solvent. This was shown by deuteriation experiments with the hydrazone (150) 319... 

Oximes, Tosylhydrazones, and Related Derivatives.—Ketoximes afford enimides in refluxing acetic anhydride-pyridine.181 Theproduct (207) from 5a-cholestan-3-one oxime (206), for example, gave 3-acetylamino-5a-cholest-2-ene (208) in 93% yield after chromatography on alumina. Use of succinic instead of acetic anhydride, with pyridine, gave the enimide (209) which was stable to chromatography. A radical mechanism is proposed. Reduction of ketoximes by Cr11, V11, or Tiin salts in acetic anhydride affords the same enamides, by acetylation of the intermediate imines. The... 

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 C=0. The bromine complex of hexamethylenetetramine is useful for regeneration of carbonyl compounds from oximes and tosylhydrazones. 

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