Hydroalumination of selenoacetylenes: a versatile generation and reactions of α-aluminate vinyl selenide intermediates in the highly regio and stereoselective synthesis of telluro(seleno)ketene acetals
作者:Palimécio G. Guerrero、Miguel J. Dabdoub、Adriano C.M. Baroni
DOI:10.1016/j.tetlet.2008.04.072
日期:2008.6
(Z)-butylseleno vinyl alanates intermediates which were captured with C4H9TeBr furnishing the (E)-telluro(seleno)ketene acetals exclusively. The isomers with opposite stereochemistry (Z)-telluro(seleno)ketene acetals were obtained by the reduction of phenylseleno acetylenes with lithium di-(isobutyl)-n-butyl aluminate hydride (Zweifel’s reagent) followed by reaction of (E)-phenylseleno vinyl alanates intermediates
丁基硒炔乙炔与DIBAL-H的氢铝化反应,然后添加原位生成的(Z)-丁基硒代乙烯基丙二酸酯中间体,用C 4 H 9 TeBr捕获的正丁基锂,专门提供(E)-碲基(硒代)乙烯酮缩醛。通过用二(异丁基)-正丁基铝酸氢化铝锂(Zweifel试剂)还原苯基硒基乙炔,然后使(E)-苯基硒基乙烯基化合物反应,可获得具有相反立体化学(Z)-碲(硒基)乙烯酮缩醛的异构体用C 4 H 9 TeBr丙酸酯中间体。
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.
Zirconium-Catalyzed Alkyne Carbo- and Cycloalumination Reactions in Stereoselective Preparation of 1-Alkenyl Selenides
(Z)-1-alkenyl selenides in high yields. Alternatively, (E)-1-alkenyl selenides were prepared by the reaction of 1-alkenylaluminums with organic diselenides in a one-potprocedure starting from the corresponding 1-alkynes, which provides a versatile tool for the preparation of stereo-defined unsaturated organic derivatives of selenium. The Cp2ZrCl2-catalyzed methylalumination and сycloalumination of 1-alkynyl