Isothiourea-Catalysed Asymmetric C-Acylation of Silyl Ketene Acetals
作者:Philip A. Woods、Louis C. Morrill、Ryan A. Bragg、Andrew D. Smith
DOI:10.1002/chem.201100995
日期:2011.9.19
Screening of a range of chiral isothioureas and acyl donors to promote the asymmetric C‐acylation of silylketeneacetals indicates that C(2)‐aryl‐dihydropyrimidobenzothiazole‐derived isothioureas and propionic anhydride give optimal reactivity and enantioselectivity in this process. Under optimised conditions 3‐acyl‐3‐aryl or 3‐acyl‐3‐alkylfuranones are prepared in good yields and moderate to excellent
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).