Synthesis of ketene phenyl- and butyltelluroacetals by a Horner–Wittig route
作者:Claudio C. Silveira、Rodrigo Cella、Antonio L. Braga、Raquel G. Jacob、Eder J. Lenardão、Gelson Perin
DOI:10.1016/j.tet.2005.05.085
日期:2005.8
New and efficient methods were developed to prepare ketene organyltelluroacetals in moderate to excellent yields. This was accomplished by reaction of phenyl- or butyltelluromethylphosphonates with phenyl- or butyltellurenyl halides and aldehydes or cyclohexanone, under basic conditions. This Horner–Wittig protocol allows the preparation of several new tri- and tetra-substituted olefins.
Hydrozirconation of acetylenic chalcogenides. Synthesis and reactions of zirconated vinyl chalcogenide intermediates
作者:Miguel J. Dabdoub、Mauro L. Begnini、Palimécio G. Guerrero
DOI:10.1016/s0040-4020(98)00014-3
日期:1998.3
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 trisubstituted olefins, such as alpha-halo vinyl tellurides, ketene telluro(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 alpha-zirconated 19 and beta- zirconated 20 vinylic selenide intermediates. After a derailed study was established that the use of 2.0 equivalents of Cp2Zr(H)Cl is crucial to perform the total hydrozirconation of acetylenic selenides or tellurides. (C) 1998 Elsevier Science Ltd. All rights reserved.