through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetricallenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee)
Dynamic Kinetic Asymmetric Allylic Alkylations of Allenes
作者:Barry M. Trost、Daniel R. Fandrick、Diana C. Dinh
DOI:10.1021/ja0543705
日期:2005.10.1
The dynamic kineticasymmetricallylicalkylations of racemic allene acetates has been developed with the DACH−phenyl Trost ligand 2 to give general access to allenes with high enantiomeric excess (84−95%) for both malonate and amine nucleophiles. Further, a most unusual dependence of enantioselectivity on base has been uncovered. The magnitude of the enantioselectivity is heavily dependent on the
An enantioselective synthesis of allenes through palladium-catalyzed asymmetric allylicalkylation using a chiral diaminophosphine oxide is described. The asymmetric allylicalkylations proceeded in the presence of a catalytic amount of lithium acetate at 4 °C, affording the chiral allenes in excellent yield with up to 99% ee.
Construction of Acyclic All‐Carbon Quaternary Stereocenters and 1,3‐Nonadjacent Stereoelements via Organo/Metal Dual Catalyzed Asymmetric Allenylic Substitution of Aldehydes
A novel synthetic strategy for the asymmetric allenylic substitution of aldehydes, which enables the construction of allene-containing acyclic all-carbonquaternarystereocenters and 1,3-nonadjacent stereoelements, has been reported.