The first asymmetric Cu-catalyzed conjugate addition of dialkylzinc zinc reagents to a large scope of enals in presence of phosphoramidite, SimplePhos, or (R)-BINAP ligands with enantiomeric excesses up to 90% is reported. Moreover, ACA of Grignard reagents afforded moderate to good 1,4-regioselectivities with enantioselectivities up to 90%.
Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities. β-Substituted aldehydes constitute a very important
Rearrangement of Allylic and Propargylic Alcohols Catalyzed by the Combined Use of tetrabutylammonium perrhenate (VII) and p-toluenesulfonic acid
作者:Koichi Narasaka、Hiroyuki Kusama、Yujiro Hayashi
DOI:10.1016/s0040-4020(01)88874-8
日期:1992.1
Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while, β,γ-unsaturated ketones are obtained as main products by the reaction
An efficient method for Pd-catalyzed stereospecific allyl-aryl coupling of allylic alcohols with arylboronicacids has been described. The reactions proceeded smoothly in the presence of Pd2(dba)3.CHCl3 and racemic BINAP under mild and neutral conditions, affording allyl-aryl coupling products in moderate to high yields with excellent stereospecificities.