The condensation of active methylene compounds 1 with acetaldehyde was efficiently promoted by a catalytic amount of lithium bromide in the presence of acetic anhydride to give ethylidene malonates 2 in 77-97% yield.
Phase-Transfer-Catalyzed Asymmetric Conjugate Cyanation of Alkylidenemalonates with KCN in the Presence of a Brønsted Acid Additive
作者:Yan Liu、Seiji Shirakawa、Keiji Maruoka
DOI:10.1021/ol400143m
日期:2013.3.15
Highly enantioselective conjugate cyanation of alkylidenemalonates with KCN was achieved under mild phase-transfer conditions with a bifunctional phase-transfer catalyst. The effect of Brønstedacid additives was examined based on the hypothetical catalytic cycle, and the Brønstedacid additive was found to be essential to promote the conjugate cyanation efficiently.
Catalytic Asymmetric Intermolecular Stetter Reaction of Glyoxamides with Alkylidenemalonates
作者:Qin Liu、Stéphane Perreault、Tomislav Rovis
DOI:10.1021/ja805680z
日期:2008.10.29
An asymmetric intermolecular Stetter reaction of glyoxamide and alkylidenemalonates has been developed. Catalyzed by a novel N-heterocyclic carbene, the Stetter adducts are formed in good yield and excellent enantioselectivity. The presence of a sensitive epimerizable stereocenter is tolerated under these mildly basic reaction conditions if a bulky amine base is used. The products may be further elaborated to provide synthetically useful intermediates.
Construction of contiguous quaternary and tertiary carbon centres via the asymmetric Michael reaction
作者:Kiyoshi Tomioka、K?suke Yasuda、Kenji Koga
DOI:10.1039/c39870001345
日期:——
Michaelreactions of chiral lithioenamines of α-alkyl β-oxo esters with methyl ethylidenemalonate afforded, after hydrolysis, adducts having contiguousquaternary and tertiarycarboncentres, with nearly complete enantio- and diastereo-selectivity.