Microwave-Assisted Group-Transfer Cyclization of Organotellurium Compounds
2004 (English)In: The Journal of Organic Chemistry, Vol. 69, no 15, 5143-5146 p.Article in journal (Refereed) Published
Primary- and secondary-alkyl aryl tellurides, prepared by arenetellurolate ring-opening of epoxides/O-allylation, were, found to undergo rapid (3-10 min) group-transfer cyclization to afford tetrahydrofuran derivatives in 60-74% yield when heated in a microwave cavity at 250C in ethylene glycol or at 180C in water. To go to completion, similar transformations had previously required extended photolysis in refluxing benzene containing a substantial amount of hexabutylditin. The only drawback of the microwave-assisted process was the loss in diastereoselectivity wich is a consequence of the higher reaction temperature. Substitution in the Te-aryl moiety of the secondary-alkyl aryl tellurides (4-OMe, 4-H, 4-CF3) did not affect the outcome of the group-transfer reaction in ethylene glycol. However, at lower temperature, using water as a solvent, the CF3 derivative failed to react. The microwave-assisted grouptransfer cyclization was extended to benzylic but not to primary- and secondary-alkyl phenyl selenides.
Place, publisher, year, edition, pages
2004. Vol. 69, no 15, 5143-5146 p.
IdentifiersURN: urn:nbn:se:uu:diva-69538OAI: oai:DiVA.org:uu-69538DiVA: diva2:97449