Oxytelluration of olefins to (β-alkoxy- and β-hydroxy-alkyl)aryltellurium dihalides and their reactions with reducing agents and aqueous NaOH |
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Authors: | Sakae Uemura Shin-Ichi Fukuzawa Akio Toshimitsu |
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Institution: | Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 Japan |
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Abstract: | Treatment of olefinic hydrocarbons with phenyltellurium tribromide or a mixture of diphenylditelluride and bromine in alcohol affords (β-alkoxyalkyl)phenyltellurium dibromides in fair to good yield (alkoxytelluration of olefins). Various aryltellurium trichlorides, diphenylditelluride/CuCl2, and phenyltellurocyanate/CuCl2 can be used for the preparation of (β-alkoxyalkyl)aryltellurium dichlorides. Similar reactions in aqueous tetrahydrofuran or aqueous t-butyl alcohol result in the formation of the corresponding β-hydroxy compound (hydroxytelluration of olefins). The reaction is trans stereospecific in the cases of cis-2-butene and cis- and trans-4-octenes and regiospecific in the cases of all terminal olefins examined (1-hexene, 1-octene, 1-decene, styrene, α-methylstyrene, 2-methyl-1-pentene, and isobutylene), tellurium species attacking the terminal carbon solely. The diorganyltellurium dihalide produced is reduced to the corresponding diorganyltelluride by reducing agents such as N2H4, Na2S, Na2S2O3, and NaHSO4 in aqueous solution. Treatment of the diorganyltellurium dibromide with aqueous NaOH affords either an allylic ether (by telluroxide elimination) or a telluroxide depending on the structure of the telluroxide. |
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