Lewis Base Activation of Lewis Acids: Catalytic, Enantioselective Addition of Silyl Ketene Acetals to Aldehydes
作者:Scott E. Denmark、Gregory L. Beutner、Thomas Wynn、Martin D. Eastgate
DOI:10.1021/ja047339w
日期:2005.3.1
The concept of Lewisbase activation of Lewisacids has been reduced to practice for catalysis of the aldolreaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl4), can be activated by binding of a strongly Lewis basic chiral phosphoramide, leading to in situ formation of a chiral Lewisacid. This species has proven to be a competent
Stereochemical consequences in the deprotonation of enoates
作者:Paul Galatsis、Jeffrey J. Manwell、Scott D. Millan
DOI:10.1016/0040-4039(96)01144-6
日期:1996.7
A cyclic transition structure for the deprotonation of enoates was proposed to rationalize the geometry of the deconjugated olefin and the substrate reactivity patterns.
作者:Denisa Hidasová、Martin Janák、Emanuela Jahn、Ivana Císařová、Peter G. Jones、Ullrich Jahn
DOI:10.1002/ejoc.201801139
日期:2018.10.9
With a single jump anti‐β‐amino‐α‐hydroxy esters or amides are obtained by merging polar aza‐Michael additions of chiral 1‐phenylethylamides to α,β‐unsaturated carboxylic acid derivatives and diastereoselective radical coupling with persistent free radical TEMPO.
Enantioselective 1,3-dipolar cycloaddition reactions using chiral lanthanide catalysts
作者:W. Marek Gołȩbiewski、Mirosław Gucma
DOI:10.1002/jhet.5570450620
日期:2008.11
Regio- and stereoselective 1,3-dipolarcycloaddition of nitrile oxides to internal 2-pentenols, α,β-unsaturated esters and amides catalyzed by R-(+) BINOL-lanthanide complexes affords corresponding 3-aryl-2-isoxazolines with enantioselectivities up to 89% ee.
R -(+)BINOL-镧系元素配合物催化的腈氧化物与内在的2-戊烯醇,α,β-不饱和酯和酰胺的区域和立体选择性1,3-偶极环加成反应提供了对映选择性最高的相应的3-芳基-2-异恶唑啉到89%ee。
Lithium (α-methylbenzyl)allylamide: a differentially protected chiral ammonia equivalent for the asymmetric synthesis of β-amino acids and β-lactams
作者:Stephen G. Davies、David R. Fenwick
DOI:10.1039/c39950001109
日期:——
The addition products from the highly stereoselective conjugateadditions of lithium (αS)-(α-methylbenzyl)allylamide to α, β-unsaturated tert-butyl esters are efficiently deallylated with tris(triphenylphosphine)rhodium(I) chloride and converted, after transesterification to the methyl esters and cyclisation with methylmagnesiumbromide, to the corresponding homochiral N-(α-methylbenzyl)-4-substituted-azetidm-2-ones