Tellurium atoms, reaction + olefins

When olefins with a hydroxy group in a y- or -position to the double bond are used in these addition reactions, phenyl tellurium oxides with five- or six-membered cyclic ether groups bonded to the tellurium atom are obtained3. Examples of such reactions are (for other compounds see p. 433) ... 

Phenyl tellurium trihalides react with linear olefins and cycloalkenes in methanol or other alcohols. In contrast to reactions in inert organic solvents, in alcoholic media the intermediate adduct between the olefin and the positive phenyldihalotelluro group is attacked by the alcohol and not by the halide ion. Therefore, the product is a 2-alkoxyalkyl phenyl tellurium dihalide. The reactions are regiospecific (tellurium bonding to the less hindered carbon atom) and highly stereospecific (anti-addition). 

A reaction sequence starting with bis[phenyltelluro]methane leads, via an alkyl phenyl tellurium oxide, to a terminal olefin. The olefin has one more carbon atom than the alkyl halide used to prepare the phenyl alkyl tellurium1,2. 

Alkyl phenyl telluriums react with AT-chloro-A-sodio-4-methylbenzenesulfonamide in refluxing THF to yield terminal olefins from prim, alkyl groups and a mixture of 1 -alkenes and 2-alkenes from sec. alkyl groups. Diorgano tellurium imides were postulated as intermediates. Considering the synthesis of the alkyl phenyl tellurium from an alkyl halide and benzenetellurolate, the overall reaction is the conversion of an alkyl halide to an olefin. Starting with lithiomethyl phenyl tellurium and an alkyl halide, the resulting olefin will have one carbon atom more than the alkyl halide. ... 

Clearly, more research needs to be done. For instance, there is a real need for more detailed product studies. The initial products with oxygen and sulphur atoms are the epoxides and episulphides. With selenium and tellurium the cyclic adducts are apparently only transient, so there is no accumulation of initial product to serve as a measure of the reaction rate. Callear and Tyerman [123] measure the selenium—olefin reaction rate by photometric methods, in which the appearance of bands attributed to an alkyl selenide are observed. These products are not stable, and decay according to... 

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