HYDROZIRCONATION OF ACETYLENIC CHALCOGENIDES - SYNTHESIS AND REACTIONS OF ZIRCONATED VINYL CHALCOGENIDE INTERMEDIATES

Acetylenic tellurides react with Cp2Zr(H)Cl in THF at room temperature to give the alpha-zirconated vinyl telluride intermediates 39, which react with a wide range of electrophiles to give several types of tris ubstituted olefins, such as alpha-halo vinyl tellurides, ketene tellur o(seleno) acetals, ketene telluro acetals, and vinylic tellurides of Z configuration. Acetylenic selenides undergo similar reactions, but a lack of regioselectivity results in the formation of a mixture of alph a-zirconated 19 and beta- zirconated 20 vinylic selenide intermediates . After a derailed study was established that the use of 2.0 equivalen ts of Cp2Zr(H)Cl is crucial to perform the total hydrozirconation of a cetylenic selenides or tellurides. (C) 1998 Elsevier Science Ltd. All rights reserved.