Allylic phenyl tellurides

Allylic phenyl tellurides are converted into the corresponding allylic amines by imination with [iV-(p-toluene-sulphonyl)imino] phenyliodinane. The reaction proceeds via [2,31-sigma-tropic rearrangement of a tellurimide intermediate. 

Allylic phenyl tellurides, prepared in situ from the corresponding halides and diphenyl ditelluride, were converted by Phi = NTs, through a [2,3] sigmatropic rearrangement of ylidic intermediates, into A-tosylated allylic amines, e.g. [49] ... 

Allyl tosyl amides. Reaction of allyl phenyl tellurides which are obtained from the corresponding halides (in situ) with TsN=IPh (or chloramine T) furnishes the amides. 

As in the selenium case (Scheme 17) the oxidation of alkyl phenyl telluride with excess MCPBA in the presence of alcohols results in a facile substitution of a PhTe moiety by an alkoxy group. The reaction is assumed to proceed via a similar tellurone-MCPBA adduct intermediate. Oxidation of cycloalkyl telluride (61) was accompanied by ring contraction to produce an acetal (62), < while the bromination-hydrolysis method affords the allylic ether by telluroxide elimination (Scheme 22). ... 

Barton and Crich reported the first examples of the uses of 2-substituted allylic sulfur compounds [53]. Their initial experiments with additions of simple alkyl radicals to allyl sulfides, sulfoxides and sulfones were relatively unsuccessful. This failure was largely due to the fact that the nucleophilic alkyl radicals, which were generated by photolysis of the corresponding Barton ester, underwent addition to a second equivalent of Barton ester faster than they added to the allyl transfer agent. Reactions were much more successful with the electron-deficient acrylate reagent 93 (Fig. 4). Crich was later able to show that this same reagent underwent addition reactions with an acyl radical derived from an acyl phenyl telluride [54]. 

Diisobutyl 2-Propen-l,l-ylideoe TeBurium4 0.87 g (2.4 mmol) of allyl diisobutyl telluronium bromide and 0.27 g (2.4 mmol) of potassium fert-butoxide are placed in a nitrogen-filled vessel. The vessel and 4 ml of dry tetrahydrofuran are cooled to — 78°. With stirring, the tetrahydrofuran is added dropwise to the mixture, stirring is continued for a few minutes, and then a solution of 0.216 g (2 mmol) of bcnzaldehydc in 2 ml of tetrahydrofuran is added dropwise to the ylide. The mixture is allowed to warm slowly to 20°. Work up and column chromatography on silica gel gives diisobutyl telluride and 2-phenyl-3-vinyIoxirane yield 82%. 

Olefins and allylic alcohols from alkyl or cycloalkyl bromides and from epoxides (general procedures The i-alkyl or cycloalkyl bromide is treated with sodium phenyl tellurolate (1 equiv from diphenyl ditelluride and NaBH, see Section 3.1.3.2). The crude telluride is purified by SiOj chromatography (elution with hexane) and converted into the corresponding dibromide by addition of bromine (1 equiv) in CCI4, at 0°C. Epoxides are converted into j8-hydroxylalkyl and )3-hydroxycycloalkyl phenyl tellurium dibromide by a similar procedure, except that the intermediate tellurides are chromatographed on SiOj using hexane/EtOAc (5 1) as the eluent. 

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