New phosphine-imine and phosphine-amine ligands derived from d -gluco-, d -galacto- and d -allosamine in Pd-catalysed asymmetric allylic alkylation
作者:Izabela Szulc、Robert Kołodziuk、Anna Zawisza
DOI:10.1016/j.tet.2018.02.009
日期:2018.3
New phosphine-imine and phosphine-amine chiral ligands which were easily prepared from d-gluco-, d-galacto- and d-allosamine furnished a high level of enantiomeric excess (up to 99%) in the Pd(0)-catalysed asymmetricallylicalkylation of racemic 1,3-diphenyl-2-propenyl acetate with malonates.
To shed light on the scope and limitations of palladium-catalyzed allylic alkylation in the presence of chiral trans-1,2-diaminocyclohexane-derived Fei-Phos as an effective phosphine ligand, the asymmetric palladium-catalysed alkylation of structurally diverse hard/soft nucleophiles, including allylic etherification of alcohols and the allylic alkylation of activated methylene compounds, indoles, and
Chiral Phosphoric Acid Catalyzed Atroposelective C−H Amination of Arenes
作者:Wang Xia、Qian‐Jin An、Shao‐Hua Xiang、Shaoyu Li、Yong‐Bin Wang、Bin Tan
DOI:10.1002/anie.202000585
日期:2020.4.20
their prevalence in natural products and functional OLED materials. C-H amination of arenes has been widely recognized as the most efficient approach to access these structures. Conventional strategies involving transition-metal catalysts suffer from confined substrate generality and the requirement of exogenous oxidants. Organocatalyticenantioselective C-N chiral axis construction remains elusive. Presented
the metal-catalyzed allylic substitution and conjugate 1,4-addition reactions of several substrate types. We have been able to identify ligands that provided promising enantioselectivities in the Pd-catalyzed intermolecular allylic substitution of cyclic substrates (ee’s up to 86%) and desymmetrization (ee’s up to 94%) and in the Cu-catalyzed conjugate addition of challenging aliphatic enones (ee’s