porous palladium(II)‐polyimines are excellent catalysts for cooperatively catalyzed and enantioselective cascadereactions. In synergy with a chiral amine co‐catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all‐carbon quaternary stereocenter, were synthesized in high yields. High diastereo‐ and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations
The reaction mechanism for the palladium and amine cocatalyzed carbocyclization of aldehydes with alkynes has been investigated by means of density functional theory calculations and experiments. The Pd/amine cocatalyzed transformation is a carbocyclization of in situgenerated enaminynes where the C–C bond-forming step is most likely promoted by a Pd(II) species. Notably, the latent Pd(0)/Pd(II) catalytic
Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations
作者:Luca Deiana、Lorenza Ghisu、Samson Afewerki、Oscar Verho、Eric V. Johnston、Niklas Hedin、Zoltan Bacsik、Armando Córdova
DOI:10.1002/adsc.201400291
日期:2014.8.11
AbstractA modular design for a novel heterogeneous synergistic catalytic system, which simultaneously activates the electrophile and nucleophile by the combined activation modes of a separate metal and non‐metal catalyst, for asymmetric cascade transformations on a solid surface is disclosed. This modular catalysis strategy generates carbocycles (up to 97.5:2.5 er) as well as spirocyclic oxindoles (97.5:2.5 to >99:0.5 er), containing all‐carbon quaternary centers, in a highly enantioselective fashion via a one‐pot dynamic relay process.magnified image