β-unsaturated α-oxo esters 1a−d and cyclic and acyclic ketone enolethers 2a−l afforded heteroadducts 3−5 in high yields when either [Eu(fod)3] or SnCl4 were used as the catalyst. With methyl (E)-benzylidenepyruvate (1a), the two catalytic modes displayed divergent stereoselectivities. In the case of the heterocycloaddition of silyl enolether 2h, X-ray investigations established the relative configurations
Low temperature syntheses of thioketals from enol ethers and carbonyl compounds
作者:Arnaud Martel、Sopa Chewchanwuttiwong、Gilles Dujardin、Eric Brown
DOI:10.1016/s0040-4039(02)02855-1
日期:2003.2
A dithioacetalisation procedure at low temperature using TMSOTf as the promoter is described. This method proved highly efficient for unprecedented transprotection of ketone enolethers and was successfully applied to polyfunctional sensitive substrates.
CLARK R. D.; UNTCH K. G., J. ORG. CHEM. 1979, 44, NO 2, 248-253
作者:CLARK R. D.、 UNTCH K. G.
DOI:——
日期:——
[2 + 2] Cycloaddition of ethyl propiolate and silyl enol ethers
作者:Robin D. Clark、Karl G. Untch
DOI:10.1021/jo01316a020
日期:1979.1
Eu(fod)3 and SnCl4-catalyzed heterocycloadditions of O-silyl enol ethers deriving from cyclic ketones
作者:Gilles Dujardin、Arnaud Martel、Eric Brown
DOI:10.1016/s0040-4039(98)01969-8
日期:1998.11
O-t-Butyldimethylsilyl enolethers deriving from simple cyclic ketones acted as efficient dienophiles in the Lewis acid-catalyzed heterocycloadditions with methyl benzylidenepyruvate 1. Good selectivities were observed with cyclohexanone derivatives. Using Eu(fod)3, the dienophile 2b led to the expected endo adduct 3b (93–97%). When using SnCl4, the major product (89–95%) was found to be the “abnormal”