Diastereoselective synthesis of α,β-unsaturated systems
摘要:
Functionalized Z-vinylic tellurides were used in substitution reactions with lower order cyanocuprates leading to alpha, beta-unsaturated ketones and esters in good yields. In the case of acyclic tellurides, the product was obtained in high diastereoselectivity. The control of the stereoselectivity was achieved by simple change of the reaction temperature. (C) 2005 Elsevier Ltd. All rights reserved.
A general method of synthesis of functionalized Z-vinylic tellurides starting from β-dicarbonyl compounds
作者:Rafael E Barrientos-Astigarraga、Priscila Castelani、Celso Y Sumida、Julio Zukerman-Schpector、João V Comasseto
DOI:10.1016/s0040-4020(01)01204-2
日期:2002.2
Z-Vinylic tellurides are prepared by stereoselective vinylic substitution on Z/E mixtures of enolphosphates, acetates, tosylates and triflates by organotellurolates. The reaction is sensitive to the nature of the organotellurolate; the aromatic derivatives react slower than the aliphatic ones. The reaction time is not influenced by the nature of the leaving group.
Carbon–carbon bond formation by means of organotellurium compounds
作者:R Barrientos-Astigarraga
DOI:10.1016/s0022-328x(00)00828-7
日期:2001.3.30
vinylic halides, phosphates, sulphonates and acetates leading to the Z vinylic telluride exclusively. Tellurides are transmetallated with easily available organometallic reagents to give valuable synthetic building blocks (e.g. organolithiums and organocuprates). Reaction of vinylic tellurides with alkynes under Pd catalysis or with organocuprates gives the coupling products with retention of the double bond
Diastereoselective synthesis of α,β-unsaturated systems
作者:Priscila Castelani、João V. Comasseto
DOI:10.1016/j.tet.2005.01.025
日期:2005.2
Functionalized Z-vinylic tellurides were used in substitution reactions with lower order cyanocuprates leading to alpha, beta-unsaturated ketones and esters in good yields. In the case of acyclic tellurides, the product was obtained in high diastereoselectivity. The control of the stereoselectivity was achieved by simple change of the reaction temperature. (C) 2005 Elsevier Ltd. All rights reserved.
Synthesis of functionalized tri- and tetrasubstituted vinylic tellurides from enolphosphates through vinylic substitution by lithium butyltellurolate
Vinylictellurides are precursors of important highly reactive vinylic organometallics (e.g. vinyl Li and Cu species). Herein we report that tri- and tetrasubstituted functionalized vinylictellurides can be prepared from enolphosphates through a vinylic substitution by lithium butyltellurolate. Starting from mixtures of Z- and E-enolphosphates, only the Z-vinylic telluride is formed.