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Reaction of organotellurides with easily available organometallics leads to a fast and clean tellurium/metal exchange reaction, allowing the preparation of a range of functionalized organometallics with C-sp 3 , C-sp 2 , and C-sp hybridization carbanionic centers. Some synthetic applications of the tellurium/metal exchange reactions are discussed.

Several carbonyl functionalized Z-vinylic tellurides were synthesized. Infrared spectra of compounds 1 showed a peculiar pattern. Appreciable shifts to lower wavenumbers for both the VC─C and VC─O modes, as well as extensive mixing of such modes were observed. This behaviour could be rationalized in terms of a proposed Te-O interaction.

Dicloro and dibromo carbenes, generated under phase transfer conditions, add to 1-halo-1-chalcogeno alkenes, to give highly functionalized selenocyclopropanes in good yields.

Alkynyl selenides react with lithium butycyano cuprate giving an intermediate lithium vinylcyano cuprate, which is trapped with electrophiles to give several classes of vinylic selenides.

The more general methods to prepare nucleophilic and electrophilic species of tellurium and their reaction with organic substrates are reviewed. Some detelluration reactions of organic derivatives of tellurium with possible utility in organic synthesis are discussed.

Olefinic benzyl ethers react with aryltellurium trichlorides leading to tetrahydrofurans in high yields. The reaction times and yields are similar to the analogous cyclization of the corresponding olefinic alcohols. The stereoselec-tivity of the transformation is low.

The easily obtained β-phenylseleno α,β-unsaturated aldehydes react with Grignard reagents and with n-butyllithium leading to the 1,2-addition products, which upon acidic hydrolysis in the presence of silica gel afford the selenium-free α,β-unsaturated carbonyl compounds with 1,3-carbonyl transposition.

Vinylic tellurides react with higher order dialkylcyanocuprates leading to mixed vinylcyanocuprates with retention of the olefin geometry. The mixed vinylcyanocuprates react with enones giving the 1,4-addition products in good yields.

Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration.

Acetylenic selenides and tellurides were prepared in good yields by nucleophilic substitution at acetylenic carbon by reaction of selenolate and tellurolate anions with 1-bromo, 2-phenyl ethyne.

Elemental tellurium is reduced by thioureadioxide in alkaline medium, leading to disodium telluride or ditelluride, depending on the amount of thioureadioxide used. The intermediate disodium telluride or ditelluride reacts “in situ” with alkyl halides to give dialkyltellurides or dialkylditellurides in high yield.

Aryltellurium trihalides, arylselenium trihalides, organyltellurium and selenium dichlorides and organylselenoxides and telluroxides were reduced in high yield to the corresponding diaryl ditellurides and selenides with thiourea dioxide in a two phase system.

β,β-Bis-(phenylseleno) carbonyl compounds were prepared by reacting the corresponding silyl enol ether with tris-(phenylseleno) methane in the presence of tin tetrachloride.

Acetylenic selenides react rapidly with m-chloroperbenzoic acid in a mixture of tetra hydrofuran-water. Treatment of the reaction mixture with IN sodium hydroxide leads to the corresponding terminal acetylenes in high yield.

Silyl enol ethers of ketones were alkylated with α-halo-α-(phenylseleno)alkanes mediated by titanium tetrachloride: The products were β-(phenylseleno)ketones.

α-Telluroketones were prepared by reacting 4-methoxyphenyltellurium trichloride either with ketones or silyl enol ethers of ketones. The products upon pirolysis furnish α-chloro ketones.

Diarylselenides and diarylsulfides are synthesized from the corresponding diaryldiselenide and diaryldisulfide by reduction with aminoiminomethanesulfinic acid, and reaction with activated aryl halides under phase transfer conditions. The reactions yields vary from good to excellent.

Some years ago one of us1 found that diphenylallylacetic acid (I) reacts with arylselenenyl halides, naphtyl tellurenyl iodide, tellurium tetrachloride as well as with aryltellurium trichlorides to give the corresponding lactones (II) (Eqn. 1).