Enantioselective fluorination reaction of β-Ketoester-catalyzed chiral primary amine-based multifunctional catalyst systems

Abstract

The fluorination reaction is an important organic transformation for asymmetric synthesis. In this article, we reported the determination of chiral primary amine-based multicatalyst systems for enantioselective fluorination of β-ketoester. Studies on the enantioselective organocatalytic fluorination promoted by cinchona alkaloid-derived chiral primary amines in the absence of various co catalysts revealed that the combined metal salts and organocatalysts resulted in poor conversion and enantioselectivities, whereas the combinational use of L-leucine and QN-NH2 as dual primary amine catalysts led to the determination of a novel dual organocatalyst with promising catalytic activity. On the basis of these results, we revealed that the steric environment of the chiral enamine intermediate formed by the condensation of β-ketoester with the chiral primary amine is most responsible for the observed enantioselectivity. © Taylor and Francis Group, LLC.