Toluenesulfonyl hydrazone

Like any aldehydes aromatic aldehydes undergo Clemmensen reduction [758, 778] and Wolff-Kizhner reduction [759, 774] and give the corresponding methyl compounds, generally in good yields. The same effect is accomplished by conversion of the aldehydes to p-toluenesulfonyl hydrazones followed by reduction with lithium aluminum hydride (p. 106). 

Other approaches to alkylidenecycloproparenes have been attempted without success. Aromatization of appropriate alkylidenecyclopropanes or their precursors could not be realized, and flash vacuum pyrolysis of methylene phthalide and 3-methylene-2-coumaranone afforded rearrangement products rather than alkylidenecycloproparenes via extrusion of 002. The photochemical or thermal decomposition of the sodium salt of benzocyclobutenone p-toluenesulfonyl hydrazone led to products derived from dimerization of the intermediate benzocy-clobutenylidene, or from its reaction with the solvent, but no ring-contracted products were observed. When the adduct of methylene-l,6-methano[10]annulene to dicyanoacetylene (249) was subjected to Alder-Rickert cleavage, phenylacety-lene (250) was formed, which derives reasonably from the parent 234. ... 

The submitters have found that the hexane-tetramethylethylenediamine solvent system described above, which is required for toluenesulfonyl-hydrazones, may be replaced with tetrahydrofuran when triisopro-pylbenzenesulfonylhydrazones are used, provided that the electrophilic reagent is added to the vinyllithium species as soon as it is formed (as indicated by cessation of nitrogen evolution). 

B. The p-toluenesulfonylhydrazone of glyoxylic acid chloride. Caution Since hydrogen chloride and sulfur dioxide are liberated during this reaction, it should be conducted in a hood. To a suspension of 50.2 g. (0.21 mole) of glyoxylic acid / -toluenesulfonyl-hydrazone in 250 ml. of benzene is added 30 ml. (49 g. or 0.42 mole) of thionyl chloride (Note 5). The reaction mixture is heated under reflux with stirring until vigorous gas evolution has ceased and most of the suspended solid has dissolved (about... 

Saturated ketones and aldehydes are converted via their p-toluenesulfonyl-hydrazones or trisylhydrazones to the corresponding alkanes by treatment with bis(triphenylphosphine)copper(I) tetrahydroborate (55) (Eq. 122) Neither aro-... 

Thiete structures have been suggested as fragmentation products in the mass spectra of a thietane fused to a 3-lactam, an ortho disulfide of a thiolbenzoate ester, -propanethiol, thiirane carboxylic acid esters, isothiazoles, thiazoles, 1,3-dithiole 2-thiones, 1,3-dithiolene-2-ones, S-ethyl thio-benzoate, and thianaphthene sulfones. Tetramethylthiete may have been formed on thermolysis of the p-toluenesulfonyl-hydrazone of 2,2,4,4-tetramethyl-3-thietanone. " Thiete 2-thione may be an intermediate in the decomposition of 1,2-ditholium salts by the action of bases. " 2,2-Diphenyl-2H-thiete is suggested as an intermediate in the reaction of diphenyldiazomethane with 1,2,3-benzo-thiadiazole which yields 9-phenylthioxanthene and three other products. ... 

The hydrazone 364 of 3-thietanone reacts with hydrogen sulfide to give the dispiro derivative 384. Thermolysis of the sodium salts of p-toluenesulfonyl-hydrazones of 3-thietanone,2,2,4,4-tetramethyl-3-thietanone and 2-isopropylidene-4,4-dimethyl-3-thietanone yields allene or cumulene epi-sulfides, for example, 385. The reactions of some tris-iminothietanes are discussed in Section XV.3.B. ... 

The semicarbiizoiic " " and para-loluenesulfonylhydrazonc " of diethyl l-formylmeth-ylphosphonate can be metallated with NaH in THF or DME for reaction with carbonyl compounds at room temperature, whereas the oxazine and dimethylhydra/inc -derivatives require metallation with n-BuLi in THF at low temperature. The oxazine protecting group is removed by sequential treatment with NaBH4 and aqueous oxalic acid at reflux. The pora-toluenesulfonyl-hydrazone participates in cyclization reactions with the release of sodium para-toluenesulfinate to produce pyrazoles (Scheme... 

Mono(/ -toluenesulfonyl)hydrazones formed from a-dicarbonyl compounds and / -toluenesulfonohydrazide split off the toluenesulfonyl group when treated with alkali or, in some cases, spontaneously, and thus yield a-diazo carbonyl compounds.9 33,934... 

Carbenes are best produced by thermal decomposition of diazo compounds that are formed in situ for example, the sodium salt of a / -toluenesulfonyl-hydrazone is decomposed at 130-150° it is best to effect this decomposition in a proton-free solvent, usually Diethylcarbitol, which avoids a competing reaction that involves carbonium ions ... 

The Bamford-Stevens synthesis is related to the Shapiro reaction (Shapiro and Heath, 1967 reviews Shapiro, 1976 Adlington and Barrett, 1983), in which a 4-toluenesulfonyl hydrazone of an aldehyde or a ketone is treated with at least two equivalents of a very strong base, usually, methyllithium (see Organic Syntheses examples of Chamberlin et al., 1983, and Shapiro et al., 1988). The Shapiro reaction leads to an olefin by a hydrogen shift. The mechanism has been proposed by Casanova and Waegell (1975) as given in (2-34). This mechanism involves a diazenide anion 2.81 as intermediate. 

The Bamford-Stevens reaction is frequently used not for the isolation of aliphatic diazo compounds, but for the synthesis of the products obtained by dediazoniation either by the carbene or the carbocation mechanisms in (2-38). As 4-toluenesulfonyl-hydrazones are fairly stable under Bamford-Stevens conditions, the reactions must be carried out at higher temperature, which is, of course, a disadvantage when it is desired to stop the reaction at the diazoalkane stage. Yields above 90% can, however, be obtained in some cases, particularly for the synthesis of 9-diazofluorene (Dudman and Reese, 1982). 

No drastic reaction conditions are required for Bamford-Stevens reactions of a-diketone mono-4-toluenesulfonyl hydrazones. The conditions are similar to those of quinone mono-4-toluenesufonyl hydrazones discussed in Section 2.6. 

Kirmse et al. (1991) came more closely to a differentiation between classical and nonclassical carbocation intermediates in deamination by the photolytic formation and nucleophilic substitution of diazonium ions from the 4-toluenesulfonyl hydrazones of 6,6-dimethyl- and 5,5,6,6-tetraalkylnorbornan-2-one 7.117, 7.118 and 7.119 (Scheme 7-36). By running the reactions in D20/Na0D, the diazonium ions were labeled with deuterium in the 2-position. For all three reagents, the alkylated exo-norbornanols (from 7.117 7.120 and 7.121) showed a distribution of deuterium in positions 1 and 2 that was very close to 1 1 (49.5 50.5 to 47.6 52.4). If these deviations from an equal distribution were caused by two classical ion intermediates. 

For the deoxygenation of the aldehyde, a modem protocol involving intermediacy of the p-toluenesulfonyl hydrazone, as outlined below, was... 

Although the symmetrical olefin is the main product. Scheme 21, 8 is obtained from fenchone p-toluenesulfonyl hydrazone (tosyl hydrazone) with t-BuOK and elemental selenium. 

An alternate route to the 5,7-diene system is by the hydride induced decomposition of A 7-toluenesulfonylhydrazones (113) (31, 41). The corresponding 7-oxo-steroids (114) can be prepared by allylic oxidation of A -sterol esters with chromium trioxide-amine complexes in methylene chloride at room temperature (163). The attractive feature of this method is that the product formed in the toluenesulfonyl hydrazone decomposition is virtually free of the 4,6-diene isomer. 

The synthetic routes leading to formation of a tetrazine ring are also rather limited, and still leave room for new developments. A mild and efficient protocol for the construction of 1,4-disubstituted 1,2,4,5-tetrazines 54 from p-toluenesulfonyl hydrazones 55 in two steps was reported (13TL4645). 

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