Chemoselective reduction of β-butyltellanyl α,β-unsaturated carbonyl compounds to allylic alcohols
作者:Alcindo A. Dos Santos、Priscila Castelani、Bruno K. Bassora、José C. Fogo Junior、Carlos E. Costa、João V. Comasseto
DOI:10.1016/j.tet.2005.06.090
日期:2005.9
(Z)-β-Butyltellanyl α,β-unsaturated carbonyl compounds were stereoselectively produced by hydrotelluration of alkynones or by an addition/elimination sequence from enol tosylates. The β-butyltellanyl-enones were chemoselectively reduced with NaBH4/MeOH, NaBH4·CeCl3·7H2O/MeOH and DIBAL-H systems to the corresponding allylic alcohols with retention of the Z stereochemistry.
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.
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.