Direct Generation of Nucleophilic Chiral Palladium Enolate from 1,3-Dicarbonyl Compounds: Catalytic Enantioselective Michael Reaction with Enones
摘要:
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).
Fischerindolesynthesis with bicyclic ketones yields regioselectively linear annulated tetracyclic products when starting from ketones with a relative trans configuration. On the other hand, starting materials with a relative cis configuration give exclusively angular annulated indole derivatives. The starting materials were prepared in optically active form in three steps by a sequence of asymmetric
Facile Enantioselective Synthesis of Two New Bicyclic Chiral Templates
作者:Kevin D. Belfield、Jeongbeob Seo
DOI:10.1080/00397919508011379
日期:1995.2
Optically active bicyclic dienes, 4 and 5 have been enantioselectively prepared in three and four steps, respectively. Mixtures of predominantly either the R or S enantiomer were obtained via an asymmetric alkylation of a chiral enamine.