First asymmetric intermolecular bromoesterification catalyzed by chiral Bronsted acid

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.