Enantioselective Acylation of Silyl Ketene Acetals through Fluoride Anion-Binding Catalysis
摘要:
A highly enantioselective acylation of silyl ketene acetals with acyl fluorides has been developed to generate useful alpha,alpha-disubstituted butyrolactone products. This transformation is promoted by a new thiourea catalyst and 4-pyrrolidinopyridine and represents the first example of enantioselective thiourea anion-binding catalysis with fluoride.
Enantioselective synthesis of tertiary α-chloro esters by non-covalent catalysis
作者:Richard Y. Liu、Masayuki Wasa、Eric N. Jacobsen
DOI:10.1016/j.tetlet.2015.01.124
日期:2015.6
We report an enantioselective approach to tertiary α-chloro esters through the reaction of silyl ketene acetals and N-chlorosuccinimide. The reaction is promoted by a chiral squaramide catalyst, which is proposed to engage both reagents exclusively through non-covalent interactions. Application of the tertiary chloride products in stereospecific substitution reactions is demonstrated.