Catalytic Enantioselective Synthesis of Quaternary Stereocenters via Intermolecular C-Acylation of Silyl Ketene Acetals: Dual Activation of the Electrophile and the Nucleophile
作者:Ara H. Mermerian、Gregory C. Fu
DOI:10.1021/ja028554k
日期:2003.4.1
A nucleophile-catalyzed asymmetric intermolecular C-acylation of silylketeneacetals by anhydrides has been developed, furnishing quaternary stereocenters with high enantioselectivity. Mechanistic studies support the hypothesis that the reaction involves activation both of the silylketeneacetal (generation of an enolate) and of the anhydride (formation of an acylpyridinium ion).
Catalytic Enantioselective Construction of All-Carbon Quaternary Stereocenters: Synthetic and Mechanistic Studies of the C-Acylation of Silyl Ketene Acetals
作者:Ara H. Mermerian、Gregory C. Fu
DOI:10.1021/ja043832w
日期:2005.4.1
With the aid of an appropriate chiral catalyst, acyclic silyl ketene acetals react with anhydrides to furnish 1,3-dicarbonyl compounds that bear all-carbon quaternary stereocenters in good ee and yield. Mechanistic studies provide strong support for a catalytic cycle that involves activation of both the electrophile (anhydride -> acylpyridinium) and the nucleophile (silyl ketene acetal -> enolate).