Water-Compatible Iminium Activation: Highly Enantioselective Organocatalytic Michael Addition of Malonates to α,β-Unsaturated Enones
作者:Zhifeng Mao、Yaomei Jia、Wenyi Li、Rui Wang
DOI:10.1021/jo101188m
日期:2010.11.5
The highlyenantioselectiveMichaeladdition of malonates to α,β-unsaturated ketones in water was reported to be catalyzed by a primary−secondary diamine catalyst containing a long alkyl chain. This asymmetric Michaeladdition process was found to be effective for a variety of α,β-unsaturated ketones.
Chiralbisphosphazides complexed with lithium salts efficiently catalyze the direct enantioselective 1,4-addition of dialkyl malonates to acyclic enones. Spectroscopic studies on the stoichiometry of the bisphosphazide and lithium salt have indicated the formation of a 1:1 species as the active enantioselectivecatalyst. It is suggested that the catalyst generates a complex of the protonated phosphazide
A highlyenantioselectiveMichaeladdition of malonate derivatives to chalcone derivatives catalyzed by an N,N′‐dioxide–ScIII complex was developed, which tolerated a broad range of substrates in moderate to excellent yield with 96–99 % ee. The reaction proceeded well in EtOH or water and could be scaled to grams in good yield with 98 % ee using only 1 mol % ligand L–scandium(III) complex as a catalyst
HighlyenantioselectiveMichaeladdition of malonates to enones catalyzed by dipeptide-derived multifunctional phosphonium salts has been developed. The newly established catalytic system was characterized with its wide substrate scope featured with aliphatic aldehyde-derived enones and substituted malonates. The gram scale-up synthesis of adducts can also be successfully achieved under optimal conditions