Disulfides, diphenyl Ditellurides

Irradiation of a mixture of diphenyl disulfide and diphenyl ditelluride in the presence of vinyl cyclopropane 141 with visible light gives the ring-opened thiatelluration product 142 as an E/Z mixture.208 Similar reaction with alkynes gives the thiatelluration product 143. The product stereochemistry depends on the nature of the alkyne.208 A mixture of diphenyl diselenide and diphenyl ditelluride reacts with alkynes in a similar way (Scheme 78).208 Similar reactions with allenes are less satisfactory.209... 

Other Elements - Irradiation ((>300 nm) of the allene (366) in the presence of diphenyl diselenide affords a high yield of the adduct (367) as an El Z mixture (28 72). Diphenyl disulfide affords a complex mixture of products with the same allene while diphenyl ditelluride does not react. The difference between the sulfide and the selenide is due to the lower ability of diphenyl disulfide to react with carbon radicals. When a mixed system is used [(PhS)2 (PhSe)2 as a 1 1 mixture] mixed addition occurs. Thus with the allene (366) an almost quantitative yield of (368) is produced and other allenes (369) are also reactive imder these conditions, affording (370). The use of diphenyl selenide as a catalyst for the photochemical isomerism of some carotenoids has been described. ... 

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