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
Enantioselective Copper(I)-Phosphoramidite Catalyzed Addition of Alkylzirconium Species to Acyclic Enones
作者:Philippe M. C. Roth、Stephen P. Fletcher
DOI:10.1021/acs.orglett.5b00021
日期:2015.2.20
asymmetric conjugate addition reactions of alkylzirconium species to acyclic enones are reported. The alkylzirconium nucleophiles are generated in situ by hydrozirconation of alkenes with the Schwartz reagent. The reaction proceeds under mild and convenient conditions. A variety of functionalized nucleophiles can be used, and the method tolerates some variation in enone scope. The method uses a new chiral
Regioselective reductions of β,β-disubstituted enones catalyzed by nonracemically ligated copper hydride
作者:Karl R. Voigtritter、Nicholas A. Isley、Ralph Moser、Donald H. Aue、Bruce H. Lipshutz
DOI:10.1016/j.tet.2011.10.056
日期:2012.4
2-additions to β,β-disubstitutedα,β-unsaturatedketones have been further explored. Asymmetric reductions of enones lacking an α-substituent can be achieved with CuH complexed by DTBM-SEGPHOS in Et2O at −25 °C leading to the generation of highly valuable nonracemic allylic alcohols. The corresponding 1,4-reductions can also be achieved using the same reaction conditions by switching the ligand to a JOSIPHOS
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.