RADICAL-ADDITION OF CHALCOGEN COMPOUNDS TO CARBON-CARBON UNSATURATED BONDS

Radical addition of organic chalcogen compounds to carbon-carbon unsaturated bonds is investigated precisely. Upon irradiation with UV or visible light, organic dichalcogenides such as disulfides, diselenides, and ditellurides undergo homolysis easily to generate the corresponding chalcogen-centered radicals. Nevertheless, only very limited examples of the radical addition of organic dichalcogenides to unsaturated bonds are known hitherto. This is probably because the lower capturing ability of disulfides (in the case of disulfides) and the lower reactivity of seleno and telluro radicals toward unsaturated bonds (in the case of diselenides and ditellurides) contribute to inefficiency of the desired radical addition reactions. We have revealed that novel mixed systems of organic dichalcogenides, e.g., (PhS)(2)- (PhSe)(1) and (PhS)(2)-(PhTe)(2) successfully cause the efficient radical addition to a wide variety of carbon-carbon unsaturated compounds such as alkenes, acetylenes, dienes, and allenes, etc. The procedure disclosed provides highly selective synthesis of a series of functionalized chalcogen compounds.