Highly Enantioselective Conjugate Addition of AlMe3 to Linear Aliphatic Enones by a Designed Catalyst
作者:Paul K. Fraser、Simon Woodward
DOI:10.1002/chem.200390087
日期:2003.2.3
of AlMe(3) to linear aliphatic enones in THF at -40 to -48 degrees C in the presence of [Cu(MeCN)(4)]BF(4). At ligand loadings of 5-20 mol %, enantioselectivities of 80-93 % are realised for most substrates. To attain these values, the use of highly pure AlMe(3) is mandatory. The presence of methylalumoxane (MAO), derived by hydrolysis, leads to reduced enantioselectivity and a conjugate addition product
Amino-sugar modular ligands—useful cores for the formation of asymmetric copper 1,4-addition catalysts
作者:Antonella De Roma、Francesco Ruffo、Simon Woodward
DOI:10.1039/b813137f
日期:——
Modular phosphine ligands, synthesised rapidly from commercial N-acetylglucosamine, are very effective in copper(I)-catalysed 1,4-additions of ZnR2 to linear aliphatic enones (87â95% ee).
Cp<sub>2</sub>ZrMeCl: A Reagent for Asymmetric Methyl Addition
作者:Kilian Garrec、Stephen P. Fletcher
DOI:10.1021/acs.orglett.6b01829
日期:2016.8.5
The use of Cp2ZrMeCl is described as a source of nucleophilicmethyl in asymmetric catalysis. This easily prepared reagent is bench stable, weighable in air, and generally useful in highly enantioselective copper-catalyzed addition reactions at room temperature. Methyl is successfully (generally >90% ee) added in 1,4-additions to cyclic and acyclic α,β-unsaturated ketones to provide tertiary and quaternary
Simple phosphoramidite ligands afford good to excellent levels of enantioselectivity in 1,4-additions of AlR3 species to enones; sequential carboalumination–ACA cascades are possible.
Alkylation des esters acetylacetiques par des alcools chiraux, par deshydratation intermoleculaire. Correlation entre les puretes optiques des produits formes.
作者:Daniel Cabaret、Nicole Maigrot、Zoltan Welvart
DOI:10.1016/s0040-4039(01)92480-3
日期:——
The formation of the C and O-alkylates involves inversion of configuration and the same weak racemization.