A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both aldehydes and acetals with silylenolethers or ketene silylacetals to give the corresponding aldol adducts in moderate to high yields. The remarkable high catalytic activity of Al-MCM-41 over amorphous silica-alumina and aluminum-free mesoporous silicate was observed in the reaction
Clay montmorillonite-catalyzed regioselective addition of silyl ketene acetals to pyridine derivatives: synthesis of N-silyldihydropyridines
作者:Makoto Onaka、Ryosuke Ohno、Yusuke Izumi
DOI:10.1016/s0040-4039(01)80299-9
日期:——
Clay montmorillonite is an efficient catalyst for addition of silyl ketene acetals to pyridine derivatives with electron-withdrawing groups to afford N-silyldihydropyridines.
aldimines took place smoothly in aqueous organic solvent to afford β-aminocarbonyl compounds in high yields. The HBF4-catalyzed Mannich-type reaction also proceeded smoothly in water without organic solvent in the presence of a surfactant. A three-component synthesis starting from aldehyde, amine, and silyl enolate was successfully realized by means of a Bronsted acid in aqueous media.
Etude de la reaction chlorocarbene-acetals de cetenes
作者:N. Slougui、G. Rousseau
DOI:10.1016/s0040-4020(01)96366-5
日期:1985.1
The reaction of chloro, chloromethyl and chlorophenyl carbenoids with ketene alkylsilylacetals has been studied. Excellent yields of cyclopropanation were observed and the unstable chlorocyclopropanone acetals formed were thermallyrearranged in high yield into α-substituted α,β-ethylenic esters. This new method for the synthesis of unsaturated esters appeared complementary of the known-ones.
Synthetic Studies toward the Tetrapetalones: Diastereoselective Construction of a Putative Intermediate
作者:Wen-Ju Bai、Thomas R. R. Pettus
DOI:10.1021/acs.orglett.7b03500
日期:2018.2.16
A strategy toward tetrapetalones was explored including a site-selective ethylenation of the silyl enol ether A to afford a quaternary stereocenter that serves in a stereogenic capacity. Regio- and diastereoselective reactions were observed in conjunction with the oxidative formation of cation B, which included subsequent selective formation of either carbon–oxygen or carbon–carbon bonds at the δ or