catalytic enantioselective Michaelreaction has been developed using chiral palladium complexes. Various substrates including β-keto esters and 1,3-diketones reacted with α,β-unsaturated carbonyl compounds to give the corresponding Michael adducts in good yield with up to 99% ee, thereby affording chiral quaternary carbon centers. In these reactions, chiral palladium enolates were generated as key intermediates
Direct Generation of Nucleophilic Chiral Palladium Enolate from 1,3-Dicarbonyl Compounds: Catalytic Enantioselective Michael Reaction with Enones
作者:Yoshitaka Hamashima、Daido Hotta、Mikiko Sodeoka
DOI:10.1021/ja027075i
日期:2002.9.1
Generation of chiral palladium enolates from 1,3-dicarbonyl compounds with the palladium aqua complex and its application to the highly efficient catalytic enantioselective Michael reaction with enones are described. The palladium aqua complexes are likely to supply Brønsted base and Brønsted acid successively during the reaction. The former activates the carbonyl compounds to give chiral palladium enolates, and the latter cooperatively activates enones. Using a catalytic amount (2-10 mol %) of the palladium complexes, the various 1,3-dicarbonyl compounds including diketones and beta-ketoesters were converted to the desired Michael adducts in good yields (69-92%) with excellent enantiomeric excesses (89-99% ee).