Enantioselective Construction of All-Carbon Quaternary Stereocenters Using Palladium-Catalyzed Asymmetric Allylic Alkylation of gamma-Acetoxy-alpha,beta-unsaturated Carbonyl Compounds

摘要

We have successfully demonstrated that gamma-acetoxy-alpha,beta-unsaturated carbonyl compounds are useful starting materials for Pd-catalyzed asymmetric allylic alkylation to construct all-carbon quaternary Stereocenters.With the use of 2-5 mol % of Pd catalyst and 4-10 mol % of P-chirogenic diaminophos-phine oxides,asymmetric allylic alkylation of gamma-acet-oxy-alpha,beta-unsaturated carbonyl compounds with various prochiral nucleophiles derived from cyclic beta-keto esters proceeded in the presence of Zn(OAc)_2,providing the corresponding products with an all-carbon quaternary stereocenter in up to 95% ee.