The first successful enantioselective intermolecular bromoesterification was realized by using a chiral phosphoric acid as a catalyst. The reaction was optimized after screening 2-aminopyridine based basic catalysts. cinchona alkaloid based basic catalysts, and binol backbone based Bronsted acid catalysts. Up to 70% ee and a moderate yield were achieved under the optimized condition. An ion-pair mechanism has been suggested in order to explain the reaction results. (C) 2012 Elsevier Ltd. All rights reserved.
Study and Applications of Tetrasubstituted Hypervalent Selenium–Halogen Species in Catalytic Electrophilic Halogenations
作者:Junjie Yang、Yung-Yin Chan、Weida Feng、Ying-Lung Steve Tse、Ying-Yeung Yeung
DOI:10.1021/acscatal.2c05414
日期:2023.2.17
Electrophilic halogenation reactions are highly useful in various areas. N-Haloamides are commonly used as halogen sources because of high stability and commercial availability. In order to activate N-haloamides, Lewis basic chalcogens are commonly used as catalysts to site-isolate the strongly coordinating amide moieties. However, the corresponding trisubstituted chalcogenonium–halogen cationic intermediate